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Condensation Control in Concrete Masonry Walls

  • August 2018

INTRODUCTION

Condensation is one type of moisture to which buildings can potentially be exposed. In addition to above grade precipitates of rain, snow and ice as well as high humidity, several forms of below-grade ground-sourced moisture can also affect building envelopes. Concrete masonry walls are less affected by the problems associated with moisture infiltration and condensate than other building materials (i.e. corrosion, rotting, mold, delamination, blistering and volumetric changes). However, prolonged moisture accumulation can lead to reduced effectiveness of some types of thermal insulation, temporary frost formation and/or efflorescence. Fortunately, these problems can largely be avoided with proper wall design and construction.

Above- and below-grade condensation control strategies include: limiting air leakage and water vapor diffusion, using adequate amounts of thermal insulation, minimizing cold spots, utilizing free draining flashing and weeps, and allowing for drying. Because the condensation potential in a particular assembly can vary with the construction assembly, building type, building usage as well as environmental conditions and seasonal climate changes, however, these strategies may vary from project to project.

CONDENSATION

Warmer air can hold more water in vapor form than can cold air. When warm moist air comes into contact with a cold surface, the air cools and can no longer hold all of its water vapor—the excess moisture condenses.

Local cold spots in a wall can cause small areas of condensation. Cold spots are usually caused either by thermal bridging or by air leakage. Both can be avoided with appropriate design strategies. See TEKs 06-13B Thermal Bridges in Wall Construction and 06-14A Control of Air Leakage in Concrete Masonry Walls (refs. 1, 2) for more detailed information.

Restricting Water Vapor Flow

Water vapor can move through building envelope assemblies by diffusion and via air leakage, so both mechanisms must be considered. The amount of water vapor that travels via air movement can be several orders of magnitude greater than that due to diffusion. Therefore, limiting air leakage is an important water vapor control strategy. For detailed information on reducing air leakage, see TEK 06-14A. When an air barrier material is required, the vapor permeability of the material must be evaluated relative to the material’s location within the wall to help ensure that the air barrier material is not contributing to moisture problems due to vapor diffusion.

Proper design and construction to reduce liquid water entry into wall assemblies will also help reduce condensation potential by reducing moisture surface area and the related water vapor diffusion. The use of moisture tolerant building materials, such as concrete masonry, also reduces the potential damage from condensation and other moisture sources.

A balanced mechanical system backed by an appropriate maintenance program is assumed for optimum efficiency. Supplying draft-controlled make-up air for all exhaust fans reduces air infiltration.

When required, water vapor retarders are used to restrict water vapor diffusion (versus moisture movement due to air leakage). Although the main characteristic of water vapor retarders is vapor permeance, other considerations may include mechanical strength, adhesion, elasticity, thermal stability, fire and flammability resistance, resistance to other deteriorating elements (e.g., chemicals, UV radiation), and ease of application and joint sealing.

A vapor retarder’s effectiveness depends on both its vapor permeance and location within the wall assembly. In addition, because of the large potential for moisture movement with air movement, a vapor retarder in an assembly with high air leakage will be ineffective.

Vapor retarders can limit water vapor movement by diffusion, but can also limit the ability of the assembly to dry. Both results need to be considered in the design. In some cases, using a semi-permeable vapor retarder, or not using a vapor retarder, is recommended to ensure the wall assembly can adequately dry. Other design conditions may dictate the use of a vapor retarder of very low permeance. Each design should be evaluated with the goal of balancing the need to restrict vapor diffusion and the need to allow drying.

Materials are also available that serve as both the vapor retarder and airflow retarder, and are useful when the assessment of air flow control and vapor diffusion control so dictates.

The 2009 International Residential Code (ref. 8) defines three vapor control classes as follows:

  • Class I: <0.1 perms, such as polyethylene sheet, sheet metal or aluminum facing.
  • Class II: 0.1 – 1.0 perms, such as kraft faced fiberglass batts, and some vapor control paints.
  • Class III: 1.0 – 10 perms, such as some latex or enamel paints.

CONDENSATION CONTROL

Condensation control focuses on minimizing airflow through the wall, interrupting water vapor diffusion, maintaining temperatures above the dew point for surfaces exposed to moisture, and allowing for drying.

Condensation can occur in either summer or winter. Design strategies for moisture control (including moisture vapor and humid air) under heating conditions often differ from those for cooling conditions, even though the basic principles of moisture transfer are the same.

In cold climates, moisture tends to be driven from the warm moist interior to the cold dry exterior. Condensation control under these conditions favors strategies that hold the moisture within the insulated envelope. In hot and humid climates, warm moist exterior air is driven towards the cooler drier interior. In this case, the wall should be designed to keep the moisture on the exterior of the wall. Most climates have some combination of the above conditions. In addition, moisture control in certain building types, such as hotels, motels, and cold storage facilities, will often benefit from using the recommendation for warm humid climates, regardless of the building location.

Definitions of climate zones for condensation control are based on the climate zones used in the International Energy Conservation Code (IECC) (ref. 3). The map showing these zones can be found at http://www1.eere.energy.gov/buildings/residential/ba_climate_guidance.html. Climate zones for the United States are: Sub-arctic, very cold, cold, mixed-humid, hot-humid, hot-dry, mixed-dry and marine. These zones are illustrated in Figure 1 for the continental U.S. along with their corresponding IECC climate zones.

Recommendations by Climate Zone

The following sections describe U. S. Department of Energy (DOE) general recommendations (ref. 5) for controlling water vapor movement and allowing drying in new residential construction, based on the climate zones shown in Figure 1.

All recommendations should be considered as part of a comprehensive strategy that addresses items including moisture management (including liquid and vapor, as well as drying potential), energy efficiency, air infiltration and durability.

All Climates

Some recommendations are consistent across all climates:

  1. An air space, such as the properly drained open cores of a single wythe masonry wall or the cavity in a masonry cavity wall, is recommended in all climate zones. The air space provides a drainage plane and allows for better drying. Single wythe masonry walls with completely filled grout spaces will take longer to dry than concrete masonry walls with unfilled cores or a cavity. However, these walls have a large hygroscopic moisture capacity and tend not to be damaged by the longer drying period.
  2. Impermeable interior coverings, such as vinyl wallpaper, are not recommended for exterior walls, because their non-breathable nature tends to trap moisture, inhibit drying and therefore can contribute to mold and mildew within such finishes.
  3. Interior polyethylene vapor retarders are generally not recommended, because they limit the wall’s ability to dry towards the inside. In some cases, these may be mandated by building codes, particularly in wet climates.

In this case, wall assemblies should be carefully designed to accommodate building materials, local climate conditions, and interior moisture loads.

An additional consideration applies to masonry veneers under certain summer conditions. If masonry is not treated for water repellency, water can be absorbed during heavy rains. Subsequent solar heating evaporates some water, raising the water vapor pressure of air in the wall, and potentially causing condensation. This can be prevented by using surface or integral water repellents to restrict wetting of the masonry, or by applying parging or sheathing paper on the exterior side of the insulation.

Cold and Very Cold Climates

Roughly the northern half of the United States experiences a heating dominated climate. Many areas also experience hot summers, however, so both seasons should be considered when designing for condensation control.

In cold and very cold climates, air barriers and vapor retarders are installed on the interior side of the insulation in building envelope assemblies when used. This approach allows the wall assembly to dry towards the exterior, as long as vaporpermeable exterior materials are used. For exterior masonry walls, drywall painted with latex paint (Class III) provides a sufficient vapor retarder.

Hot-Dry & Mixed-Dry Climates

Design considerations for the dry climates tend to focus less on water vapor control and more on issues such as intense solar radiation, brief heavy rains, and managing fire risk. Wall interiors can be painted but not covered with plastic vapor retarders or impervious coatings, such as vinyl wallpaper.

Hot and Humid Climates

Moisture is a significant problem in these climates in terms of both high humidity and high rainfall. Controlling the infiltration of this moisture-laden air into the building envelope and keeping moisture away from cold surfaces are the goals of design and construction in this climate zone.

Ideally in these climates, batt insulation, if used, should be unfaced. However, codes may restrict the use of unfaced batts in wall construction. In addition, because of the susceptibility of batt insulation to moisture, its use is not generally recommended in masonry wall assemblies. Though there are some exceptions, generally all wall interiors and finishes which are part of an insulated masonry wall assembly may be painted or otherwise finished if desired so long as such finishes and assemblies are breathable and permeable as Code and Standards allow. Masonry buildings in Florida have successfully used a non-breathable elastomeric paint on the exterior of the wall to serve as the vapor retarder.

In hot-humid climates the interior space should be dehumidified. Properly sized air-conditioning equipment will help reduce indoor humidity—oversized units should be avoided because they either cycle on and off too frequently or are off for too long a time to effectively dehumidify.

In humid climates, moisture may condense on wall exteriors, because the wall temperature can be below the ambient dew point. Areas such as shaded reentrant building corners are more difficult to dry, since they do not have the benefit of sun and wind for evaporation. In addition, extra care is required for building components prone to thermal bridging, such as walls adjacent to slab or floor edges as well as parapet courses adjacent to roof joists and decks (see Ref. 1 for information on control of thermal bridges).

Mixed-Humid Climates

The mixed-humid climate zone has generally moderate conditions, but can experience very cold winters and hot, humid summers. In these areas, wall assemblies need to be protected from getting wet from both the interior and exterior and should also be allowed to dry to either the exterior or interior.

Perhaps the least costly option is to allow water vapor to “flow through,” by using vapor-permeable building materials on both the interior and exterior. This allows water vapor to diffuse through the assembly from interior to exterior during heating periods and from exterior to interior during cooling periods. If a vapor retarder is used, a semi-permeable (i.e., Class III) vapor retarder on just the interior side is considered adequate. Although the DOE suggests latex paint as an adequate vapor retarder in these climates (ref. 5d), the permeability of latex paints varies with the specific paint and the number and thickness of coats. Consult the manufacturer for specific permeabilities.

Installing vapor retarders on both the interior and exterior to block moisture entry from both directions is not recommended, as any moisture that enters the wall is trapped.

Marine Climates

The marine climate zone also has moderate conditions most of the time, although weather conditions similar to those found in neighboring climate zones occasionally occur. Buildings in the marine climate zone are faced with high interior and exterior moisture loads.

Similar to mixed-humid climates, building assemblies need to be protected from getting wet from both the interior and exterior and should be allowed to dry to either the exterior or the interior. The same wall recommendation apply to marine climates as to mixed humid climates, however, the high moisture loads in the marine climate zone warrant careful consideration of material vapor permeabilities, moisture loads and local climate conditions.

Vapor retarders may be required by building codes, but an option exists for engineered wall designs that do not require vapor retarders to be approved by building officials.

DETERMINING CONDENSATION POTENTIAL

Traditionally, condensation potential has been estimated using steady-state calculations of water vapor pressure and saturation pressures at various points in an assembly. If the calculated vapor pressure exceeds the saturation pressure, condensation is likely to occur if the assumed conditions occur in the field.

This dew point method is a simplified approach which can be used to estimate seasonal mean conditions (rather than daily or even weekly mean conditions) (see Figure 2). However, this method has several disadvantages. For example, wetting and drying cycles cannot be analyzed, since moisture storage within building materials is neglected, as is moisture transfer due to airflow. As a result, the analysis cannot accurately indicate potential damage due to condensation. A complete description of the dew point method is presented in the ASHRAE Handbook, Fundamentals (ref. 6).

Transient computer models which model heat, air and moisture response are an alternative to dew point analyses. They can be used to predict daily or hourly moisture conditions within assemblies. The ASHRAE Handbook, Fundamentals, contains a discussion of input and output parameters, as well as considerations for choosing a program and evaluating the results.

BASEMENTS

Moisture control in basements begins with proper protection from liquid moisture, such as from rain and wet soil. These considerations are addressed in TEK 19-03B, Preventing Water Penetration in Below-Grade Concrete Masonry Walls (ref. 7). If the wall is substantially above grade, condensation control recommendations for the appropriate climate, discussed above, should be followed. If substantially below grade, the basement walls will be dampproofed or waterproofed as required by local code, which essentially acts as an exterior vapor retarder. In this case, an additional interior vapor retarder should be avoided, as this may potentially trap moisture within the wall.

Moisture on the interior of basement walls may be caused by either condensation of interior moisture or leakage of liquid water through the wall. To determine the cause, tape a square of impermeable plastic (such as 6 mil polyethylene) on a portion of the wall experiencing the moisture issues. If there is moisture accumulating under the plastic, an exterior moisture source should be suspected. If moisture forms on top of the plastic, condensation is occurring.

REFERENCES

  1. Thermal Bridges in Wall Construction, TEK 06-13B, Concrete Masonry & Hardscapes Association, 2010.
  2. Control of Air Leakage in Concrete Masonry Walls, TEK 06-14A, Concrete Masonry & Hardscapes Association, 2011.
  3. International Energy Conservation Code. International Code Council, 2009.
  4. Guide to Determining Climate Regions by County, PNNL17211. Pacific Northwest National Laboratory and Oak Ridge National Laboratory, 2010.
  5. Building America Best Practices Series: Builders and Buyers Handbook for Improving New Home Efficiency, Comfort, and Durability. U. S. Department of Energy Building Technologies Program. Available at http://www1.eere.energy.gov/buildings/residential/ba_climate_
    guidance.html    .
    5a. Volume 1, Hot and Humid Climates, NREL/TP-550-36960, 2004.
    5b. Volume 2, Hot-Dry and Mixed-Dry Climates, NREL/TP550-38360, 2005.
    5c. Volume 3, Cold and Very Cold Climates, NREL/TP-550-38309, 2005.
    5d. Volume 4, Mixed-Humid Climates, NREL/TP-550-38448, 2005.
    5e. Volume 5, Marine Climates, NREL/TP-550-38449, 2006.
  6. ASHRAE Handbook, Fundamentals. American Society of Heating, Refrigerating, and Air-Conditioning Engineers., Inc., 2009.
  7. Preventing Water Penetration in Below-Grade Concrete Masonry Walls, TEK 19-03B, Concrete Masonry & Hardscapes Association, 2012.
  8. International Residential Code. International Code Council, 2009.

Control of Air Leakage in Concrete Masonry Walls

  • August 2018

INTRODUCTION

Energy efficiency in buildings has become increasingly important. Whether complying with newer energy codes or gaining recognition for sustainable building practices, reducing the overall energy usage in new and existing buildings continues to be a leading consideration for design teams.

Many methods are employed to increase building energy efficiency. One consideration is reducing air leakage through the building envelope. In addition to the negative impact on a building’s energy efficiency (due to the loss of conditioned air via exfiltration and/or the introduction of unconditioned air via infiltration), air leakage in buildings can also impact moisture control, indoor air quality, acoustics and occupant comfort.

Reduced air leakage is one area where masonry walls excel compared to other wall types when proper design criteria are applied. This TEK reviews available information on masonry wall air leakage, reviews the most recent code criteria, presents concrete masonry wall assemblies that meet this criteria, and provides general guidance on improving the control of air leakage in masonry walls.

AIR LEAKAGE

Air leakage consists of air infiltration from the exterior into the conditioned spaces of buildings and/or exfiltration of conditioned interior air out of buildings. Although under a pressure differential air can pass directly through many materials, air leakage occurs primarily through a myriad of cracks, gaps, improperly designed or constructed joints, utility penetrations, junctions between wall and window and door frames, junctions between wall and roof assemblies, and other avenues.

Historically, air leakage has been the primary source of building ventilation. Because it is uncontrolled and weather-dependent, however, the direct result of air leakage is an increase of energy consumption to maintain space conditioning. Recognition of this increased energy consumption has caused air leakage to be regulated by code for many newer commercial buildings.

Reducing air leakage rates, however, can pose potentially adverse health effects due to stale and polluted air by reducing the air exchanges that dilute contaminants. Mechanical ventilation systems are usually required to satisfy air exchange requirements that have historically been met by uncontrolled air leakage. Although there is an added cost with a designed mechanical ventilation system, it is theoretically offset by the energy savings associated with the reduced air leakage. Heat recovery or energy recovery units (HRV/ERV) can be used to reduce the amount of space conditioning required to condition the fresh air. These systems should be designed carefully, however, as some research shows that the energy consumed by operating the HRV/ERV systems could exceed the cost of conditioning the fresh air (ref. 1).

Studies have shown that air leakage in buildings can be difficult to accurately predict and measure (ref. 2). Prediction and measurement of air leakage rates in walls has been the subject of study by both U.S. and international researchers. U.S. results have focused primarily on the wood stud wall construction with fibrous insulation common to home building. International research has looked at masonry walls as well as wood frame walls, because masonry is the traditional European construction method.

AIR LEAKAGE LOCATIONS

A key issue when addressing air leakage is the significant difference between air leakage at discreet sites, such as at member junctions and at door and window openings where caulking and sealing is at issue, versus the diffuse air leakage that can occur directly through a wall assembly. Chapter 16 of the ASHRAE Fundamentals Handbook (ref. 3) includes the results of residential air leakage studies that show that the largest source of air leakage occurs through wall cracks, joints and utility penetrations. Other major leakage sources include leakage around doors and windows, ceiling penetrations and utility penetrations to the attic, and the HVAC system. The same studies showed that diffusion through walls was less than 1%; i.e., compared to infiltration through holes and other openings, diffusion through walls was not an important flow mechanism in residential buildings. These data are illustrated in Figure 1.

AIR LEAKAGE CRITERIA

To reduce air leakage rates, air barrier systems are sometimes designed and installed as part of the building envelope. Alternatively, the thermal envelope can be designed and detailed to perform as an air barrier system. Current building codes (ref. 4) do not stipulate quantitative requirements for air barriers, but instead require that the exterior envelope be sealed to minimize the infiltration/exfiltration of air through both commercial and residential building envelopes.

The 2012 International Energy Conservation Code (IECC) (ref. 5) and some local jurisdictions, however, have adopted performance requirements for the control of air leakage in commercial buildings. The 2012 IECC provides three levels of compliance, applying to air barrier materials, air barrier assemblies, or the whole building. These commercial air barrier criteria apply only to buildings in Climate Zones 4 through 8. The compliance criteria are (only one of these criteria need to be satisfied):

  • a building material intended to serve as an air barrier must have an air permeance of less than 0.004 cfm/ft2 at a pressure differential of 1.57 lb/ft2 (0.02 L/s-m2 at 75 Pa),
  • an assembly of materials intended to serve as an air barrier, such as a concrete masonry wall assembly, must have an air leakage rate of less than 0.04 cfm/ft2 at a pressure differential of 1.57 lb/ft2 (0.2 L/s-m2 at 75 Pa), or
  • a building must have an air leakage rate of less than 0.4 cfm/ft2 at a pressure differential of 1.57 lb/ft2 (2.0 L/s-m2 at 75 Pa).

Also contained within the code are several “deemed-to-comply” materials and assemblies. The following masonry-related materials and assemblies are included in this list and are therefore considered to comply with the code:

  • fully grouted concrete masonry (although listed as a material, this compliance option is more accurately deemed an assembly),
  • as a material, portland cement/sand parge or gypsum plaster with a minimum thickness of 5 /8 in. (16 mm),
  • as an assembly, portland cement/sand parge, stucco or plaster with a minimum thickness of 1 /2 in. (13 mm), and
  • concrete masonry walls coated with one application of block filler and two applications of a paint or sealer coating.

The last option is justified based on research completed in the early 2000s. More recent research has documented additional options for materials and coatings to allow concrete masonry assemblies to comply with the maximum assembly air leakage requirement of 0.04 cfm/ft2 at a pressure differential of 1.57 lb/ft2 (0.2 L/s-m2 at 75 Pa). Although not included explicitly in the code, these tested assemblies can be approved under IECC Section 102, Alternate Materials, as meeting the intent of the code. The testing is described in the Masonry Wall Assemblies section below, and the results are summarized in the Guidelines section on page 7.

The 2012 IECC also lists the following materials as acceptable air barrier materials (ref. 5). Any one of these can be used in conjunction with concrete masonry construction, as shown in Figures 2 and 3.

  • extruded polystyrene insulation board with a minimum thickness of 1/2 in. (13 mm) with joints sealed,
  • foil-backed polyisocyanurate insulation board with a minimum thickness of 1/2 in. (13 mm) with joints sealed,
  • closed-cell spray foam insulation with a minimum density of 1.5 pcf (2.4 kg/m3) with a minimum thickness of 1 1/2 in. (36 mm),
  • open-cell spray foam insulation with a density between 0.4 and 1.5 pcf (0.6 – 2.4 kg/m3) with a minimum thickness of 4 1/2 in. (114 mm), and
  • gypsum wallboard with a minimum thickness of 1/2 in. (13 mm) with joints sealed.

MASONRY WALL ASSEMBLIES

Multi-Wythe Walls

Multi-wythe concrete masonry assemblies have a variety of options available for compliance with the commercial building air leakage requirements listed above. In addition to the deemed-to-comply options, there are many proprietary air barrier materials and accessories available. Most air barrier materials are some type of coating, which is usually applied to the cavity side of the back up wythe. In addition, some types of spray-applied insulation or rigid insulation (with sealed joints) can be used as an air barrier, as illustrated in Figure 2.

Single Wythe Walls

The available options for single-wythe concrete masonry assemblies are illustrated in Figure 3. Solid grouting is available, as well as coating with a paint, sealer, or block filler. Additionally, exterior wallcoverings and interior wall finishes offer solutions, such as parge coating, stucco, plaster, various insulations and gypsum wallboard. Note that paints, sealers or block fillers are effective when applied to either the interior or exterior surface of the concrete masonry. Hence, when a coating is specified, architectural finishes need not be compromised by the coating.

Concrete Masonry Air Leakage Testing

Research sponsored by CMHA and the NCMA Education and Research Foundation (refs. 6, 7) has documented additional concrete masonry wall assemblies that can meet the air barrier assembly requirements of 0.04 cfm/ft2 at a pressure differential of 1.57 lb/ft2 (0.2 L/s-m2 at 75 Pa). The results are summarized below. See References 6 and 7 for full descriptions of the assemblies and test results.

Commercial-Grade Latex Paint

One project (ref. 6) tested the effects of commercial-grade latex paint on the air leakage rate of concrete masonry wall assemblies. The walls were ungrouted except at the four edges (which were grouted solid to isolate air permeance to a 1 m2 test surface). The research employed a modified ASTM E2178, Standard Test Method for Air Permeance of Building Materials (ref. 8), because there is no standardized test procedure specifically suited for testing concrete masonry assemblies. Three wall sets were built using plain gray concrete masonry units, each with different concrete mix designs, then tested for air leakage.

The wall sections were painted with a typical commercial-grade latex paint (28% solids content by volume), then the air leakage rate was re-measured. The research documented that the air leakage rate decreased as the paint thickness increased: it was determined that the air leakage rate of the wall was inversely proportional to the thickness of the paint applied.

While surface texture was not directly measured in this study, it is believed that the surface texture of smooth-faced concrete masonry units affects the ability of the coating material to develop a continuous coating, which is important for reducing air leakage rates through assemblies.

The results of this research indicate that the air leakage rate of 12-in. (305-mm) concrete masonry walls can be reduced to 0.04 cfm/ft2 or less at a pressure differential of 1.57 lb/ft2 (0.20 L/s-m2 at 75 Pa) by applying between 3.3 and 14.6 mils (0.084 and 0.371 mm) of commercial-grade latex paint for concrete masonry units with a smooth textured surface and a coarse textured surface, respectively.

High-Quality Latex Paint

More recent research (ref. 7) evaluated the effects of four additional coatings: a high-quality latex paint, masonry block filler, water repellent surface coatings, and gypsum wallboard. The concrete masonry units used in this study were also plain gray, medium-weight “utility” type units with a fairly open surface texture (see Figure 4). The use of integral water repellent admixtures was also investigated.

The latex paint used in this project was a high quality retail paint, with a 28% solids content by volume and 47% solids content by weight. To evaluate this paint, a single coat was applied with an average dry film thickness of 1.28 mil (0.033 mm). The paint reduced the air leakage rate by 94%, to a calculated average air leakage rate of 0.011 cfm/ft2 (0.05 L/s-m2), well below the assembly requirement of 0.04 cfm/ft2 (0.2 L/s-m2).

The results indicate that when a high quality latex paint is used, a single coat is all that is necessary to create a continuous coating and provide the required barrier to air flow.

Masonry Block Filler

The block filler evaluated was a water-based masonry primer designed for use on concrete and concrete masonry surfaces. This material is typically used as a base primer coat on concrete and masonry surfaces in preparation for painting. It is a thicker coating material than latex paint, designed to fill pores and surface imperfections in masonry walls. Based on information provided by the manufacturer, this material has a 46% solids content by volume and 55% solids content by weight.

A single coat of block filler was applied with an average dry film thickness of 2.10 mil (0.053 mm). The air leakage rate was reduced by 86% due to the presence of the block filler coating, to 0.011 cfm/ft2 (0.05 L/s-m2). This result is well below the air barrier assembly requirement of 0.04 cfm/ft2 (0.2 L/s-m2).

Gypsum Wallboard

A set of assemblies was also evaluated for air leakage after installing ½ in. (12.7 mm) gypsum wallboard to simulate a single-wythe assembly with a drywall-finished interior.

When the gypsum wallboard was tested by itself, it had an air permeance below the air barrier material requirement of 0.004 cfm/ft2 (0.02 L/s-m2). When the concrete masonry assembly was tested with wallboard attached, it was evident that the performance of the assembly was dominated by the air permeance of the wallboard, as very little air leakage was measured, and the results were below the 0.004 cfm/ft2 (0.02 L/s-m2) requirement for an air barrier material.

Water-Repellent Surface Coatings

Because many single-wythe concrete masonry assemblies use some type of water repellent surface coating, these coatings may be an efficient way to reduce air leakage rates. Both a silane/siloxane and an acrylic microemulsion water repellent coating were evaluated.

While both water repellent coatings reduced the air leakage rate of the assemblies, the reduction was not sufficient to comply with the 2012 IECC air barrier assembly requirements for commercial buildings.

Integral Water Repellents

The effect of an integral water repellent in concrete masonry units and masonry mortar was also evaluated. Integral water repellents in concrete masonry units can improve the compaction of the unit, leading to a slightly tighter concrete matrix and, in some cases, a more uniform surface texture.

The tested set of concrete masonry assemblies contained an integral water repellent admixture at an appropriate dosage to produce water repellent characteristics.

Compared to the assemblies without an integral water repellent, the addition of integral water repellent decreased the air leakage rate by 28% on average. This decrease is likely due to a slightly tighter pore structure resulting from the use of the integral water repellent. The decrease in leakage rate, however, was not sufficient to reduce the assembly air leakage rate to levels that comply with the 2012 IECC.

CONCRETE MASONRY COMPARED TO FRAME CONSTRUCTION

Typical masonry construction does not include some of the leakage sites common in frame walls. Masonry walls do not have sole plates (sills), because the wall is a continuous assembly from the footing up. The top of a masonry wall is typically a tie-beam or bond beam. Trusses or rafters are set to a plate attached to the top course of masonry. Quality caulking and sealing are important at the ceiling finish edge. Sealing is also required at attic access ways, as well as around any wall penetrations.

Commercial Buildings

Measured air leakage rates from existing commercial buildings constructed during or after 1980 have been compiled (ref. 9). From this data, 84% of the masonry buildings included had measured whole-building air leakage rates of less than 2 cfm/ft2 at a pressure differential of 1.57 lb/ft2 (10 L/s-m2at 75 Pa). In comparison, only 30% of frame-walled buildings had measured whole building air leakage rates of less than 2 cfm/ft2 at a pressure differential of 1.57 lb/ft2 (10 L/s-m2 at 75 Pa) (it should be noted that none of these buildings were constructed to meet an air tightness standard). The reported leakage rates were normalized by the above grade area of the building envelope. The data were compiled from various references, and represent a range of climates and building types, making it difficult to draw definite conclusions. The results do indicate, however, that existing masonry buildings tend to have much lower air leakage rates than existing frame-walled buildings.

Residential Buildings

The air leakage rates of masonry walls have also been researched widely in Europe by such groups as the Air Ventilation and Infiltration Center in England (ref. 10). Results from detailed air leakage work performed in Finland show that concrete masonry and lightweight concrete (panelized) walled homes had much lower air leakage rates than wood frame structures (ref. 11). Figure 5 illustrates these differences, comparing older wood frame houses averaging 7.3 air changes per hour (ACH) at 50 Pa to more modern site-built wood frame houses averaging 8.5 ACH, with a very wide range of values. Prefabricated wood element (panelized) houses were better at 6.0 ACH. Both concrete masonry and lightweight concrete houses, however, had roughly one-half the air change rate of the average panelized wood frame homes.

Proper sealing of components into masonry rough openings may be more important than reducing air leakage through masonry assemblies. Dr. Hiroshi Yoshino of Japan’s Tohoku University investigated Japanese housing air leakage (ref. 12) in a broad comparison with data from other nations. He ranked data points from his own research and other investigators into air tightness categories. He observed that some concrete multi-family housing was so air tight that indoor air quality and condensation problems resulted, and ventilation was required. Concrete masonry houses of “air-tight” construction ranked among the best in Japan for air tightness. Several of the other Japanese reports he cited also showed concrete and concrete masonry houses to have lower air leakage rates than typical Japanese frame houses.

Belgian researchers used a sequential technique in masonry homes to examine incremental air leakage measures (ref. 14). Figure 6 shows the progression of air change rates at 50 Pa from “normal construction,” which evidently assumes no air leakage reduction measures, to a masonry wall with all windows, doors and penetrations sealed and weather stripped. Sealing just these items resulted in about 87% less air leakage. The largest improvements are seen after sealing the door and window frames to their respective rough openings, which agrees with the data in ASHRAE (ref. 3). The Belgian findings also agree with a statement in a compendium of European air leakage results which states: “The critical details from the point of view of air-tightness are associated with the (quality of) formation of openings in masonry walls…” (ref. 14).

IMPACTS ON MOISTURE

When an air barrier material is required, its placement can be critical to controlling moisture and hence to wall durability.

First, because air movement can carry a significant amount of moisture into or through a building assembly, and second because the air barrier can act as a vapor retarder. Note that an air barrier is designed to control the movement of air both into and out of the building envelope, whereas a vapor retarder is designed to restrict the diffusion of water vapor through building materials and subsequent condensation. Because a vapor retarder can also inhibit drying, the need for a vapor retarder varies with climate, construction type and building use.

Although the functions of air barriers and vapor retarders differ, in some cases one component can serve both needs. In designs where one material is installed to control both air and water vapor movement, it is important that the material is continuous to provide the required level of air tightness. Where separate airflow and vapor retarders are installed, care must be taken to ensure that the air barrier cannot cause moisture condensation. This can be accomplished through the choice of vapor-permeable materials or through proper placement.

More detailed information on vapor retarders in concrete masonry walls can be found in TEK 06-17B, Condensation Control in Concrete Masonry Walls (ref. 13).

DISCUSSION

Air leakage measurements indicate that properly constructed concrete masonry walls may have better natural resistance to air leakage than typical frame construction. If a further reduction in air leakage rates is required, various options are available. Retrofits for reducing air leakage in concrete masonry construction are straightforward, because fewer dissimilar joints are involved. Also stucco, paints and mastics tend to be less expensive than new sheathing, polymer papers, etc.

GUIDELINES

The following concrete masonry wall assemblies are considered to meet an air leakage of less than 0.04 cfm/ft2 (0.20 L/s-m2) at 75 Pa,
either by prescriptive code requirements or as demonstrated through laboratory testing.

By prescriptive IECC criteria (ref. 5):

  • Fully grouted concrete masonry.
  • Concrete masonry with a portland cement/sand parge, stucco or plaster with a minimum thickness of 1/2 in. (13 mm).
  • Concrete masonry walls coated with one application of block filler and two applications of a paint or sealer coating.
  • By laboratory testing (refs. 6, 8):
  • 12-in. (305-mm) concrete masonry sealed with at least two coats of commercial-grade latex paint.
  • 8-in. (203-mm) concrete masonry coated with a single coat of high quality latex paint.
  • 8-in. (203-mm) concrete masonry coated with a single coat of masonry block filler.

It can be reasonably assumed that compliance would also be achieved by applying these coatings to walls having a larger thickness than those tested.

When coatings such as paint or block filler are called for, they can be applied to either the interior or exterior side of the concrete masonry, so any masonry architectural finishes need not be compromised.

REFERENCES

  1. Sherman, Max H. and Iain S. Walker, LBNL 62341. Energy Impact of Residential Ventilation Norms in the United States, Lawrence Berkeley National Laboratory, 2007.
  2. Carr, D. and J. Keyes, Component Leakage Values and their Relationship to Air Infiltration, Steven Winter Associates, 1984.
  3. 2009 ASHRAE Handbook – Fundamentals. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 2009.
  4. International Energy Conservation Code. International Code Council, 2006 and 2009.
  5. International Energy Conservation Code. International Code Council, 2012.
  6. Biggs, David T., Air Permeance Testing of Concrete Masonry Wall Assemblies, FR06. National Concrete Masonry Research and Development Laboratory, January 2008.
  7. Assessment of the Effectiveness of Water Repellents and Other Surface Coatings on Reducing the Air Permeance of Single Wythe Concrete Masonry Assemblies, MR36. Concrete Masonry & Hardscapes Association, 2010.
  8. Standard Test Method for Air Permeance of Building Materials, E2178-03. ASTM International, 2003.
  9. Emmerlich S. J., T. McDowell, W. Anis, Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use, NISTIR 7238. National Institute of Standards and Technology, 2005.
  10. Air Ventilation and Infiltration Center, Old Bracknell Lane West, Bracknell, Berkshire, RG12 4AH, Great Britain.
  11. Kohonen, R., S. Ahvenainen and P. Saarnio. Review of Air Infiltration Research in Finland, Air Infiltration Review Vol. 6, No. 1, 1984.
  12. Yoshiro, Dr. H. Overview of Air Infiltration in Japan, Air Infiltration Review. Vol. 5 No. 3, May 1984.
  13. Condensation Control in Concrete Masonry Walls, TEK 06-17B, Concrete Masonry & Hardscapes Association, 2011.
  14. Caluwaerts, P. and P. Nusgens. Overview of Research Work in Air Infiltration and Related Areas in Belgium, Air Infiltration Review. Vol. 5 No. 1, 1983.

Insulating Conrete Masonry Walls

  • August 2018

INTRODUCTION

The variety of concrete masonry wall constructions provides for
a number of insulating strategies, including: interior insulation,
insulated cavities, insulation inserts, foamed-in-place insulation,
granular fills in block core spaces, and exterior insulation
systems. Each masonry wall design has different advantages
and limitations with regard to each of these insulation
strategies. The choice of insulation will depend on the desired
thermal properties, climate conditions, ease of construction,
cost, and other design criteria. Note that insulation position
within the wall can impact dew point location, and hence affect
the condensation potential. See TEK 06-17B, Condensation
Control in Concrete Masonry Walls (ref. 1) for more detailed
information. Similarly, some insulations can act as an air barrier
when installed continuously and with sealed joints. See TEK
06-14B, Control of Infiltration in Concrete Masonry Walls, (ref.
2) for further information.

MASONRY THERMAL PERFORMANCE

The thermal performance of a masonry wall depends on its steady state thermal characteristics (described by R-value or U-factor) as well as the thermal mass (heat capacity) characteristics of the wall. The steady state and mass performance are influenced by the size and type of masonry unit, type and location of insulation, finish materials, and density of masonry. Lower density concrete masonry mix designs result in higher R-values (i.e., lower U-factors) than higher density concretes. Thermal mass describes the ability of materials to store heat. Because of its comparatively high density and specific heat, masonry provides very effective thermal storage. Masonry walls remain warm or cool long after the heat or airconditioning has shut off. This, in turn, effectively reduces heating and cooling loads, moderates indoor temperature swings, and shifts heating and cooling loads to off-peak hours. Due to the significant benefits of concrete masonry’s inherent thermal mass, concrete masonry buildings can provide similar performance to more heavily insulated frame buildings.

The benefits of thermal mass have been incorporated into energy code requirements as well as sophisticated computer models. Energy codes and standards such as the International Energy Conservation Code (IECC) (ref. 5) and Energy Efficient Standard for Buildings Except Low-Rise Residential Buildings, ASHRAE/IESNA Standard 90.1 (ref. 6), permit concrete masonry walls to have less insulation than frame wall systems to meet the energy requirements.

Although the thermal mass and inherent R-value/U-factor of concrete masonry may be enough to meet energy code requirements (particularly in warmer climates), concrete masonry walls often require additional insulation. When they do, there are many options available for insulating concrete masonry construction. When required, concrete masonry can provide walls with R-values that exceed code minimums (see refs. 3, 4). For overall project economy, however, the industry suggests a parametric analysis to determine reasonable insulation levels for the building envelope elements.

The effectiveness of thermal mass varies with factors such as climate, building design and insulation position. The effects of insulation position are discussed in the following sections. Note, however, that depending on the specific code compliance method chosen, insulation position may not be reflected in a particular code or standard.

There are several methods available to comply with the energy requirements of the IECC. One of the options, the IECC prescriptive R-values (IECC Table 502.2(1)) calls for “continuous insulation” on concrete masonry and other mass walls. This refers to insulation uninterrupted by furring or by the webs of concrete masonry units. Examples include rigid insulation adhered to the interior of the wall with furring and drywall applied over the insulation, continuous insulation in a masonry cavity wall, and exterior insulation and finish systems. If the concrete masonry wall will not include continuous insulation, there are several other options to comply with the IECC requirements—concrete masonry walls are not required to have continuous insulation in order to meet the IECC. See TEK 06-12E, Concrete Masonry in the 2012 Edition of the IECC and TEK 06-04B, Energy Code Compliance Using COMcheck (refs. 7, 8).

INTERIOR INSULATION

Interior insulation refers to insulation applied to the interior side of the concrete masonry, as shown in Figure 1. The insulation may be rigid board (extruded or expanded polystyrene or polyisocyanurate), closed-cell spray polyurethane foam, cellular glass, fibrous batt, or fibrous blown-in insulation (note, however, that fibrous insulation is susceptible to moisture). The interior wall surface is usually finished with gypsum wallboard or paneling.

Interior insulation allows for exposed masonry on the exterior, but isolates the masonry from the building’s interior and so may reduce the effects of thermal mass.

With rigid board insulation, an adhesive is used to temporarily hold the insulation in place while mechanical fasteners and a protective finish are applied. Furring may be used and held away from the face of the masonry with spacers. The space created by the spacers provides moisture protection, as well as a convenient and economical location for additional insulation, wiring or pipes.

As an alternative, wood or metal furring can be installed with insulation placed between the furring. The furring size is determined by the type of insulation and R-value required. Because the furring penetrates the insulation, the furring properties must be considered in analyzing the wall’s thermal performance. Steel penetrations through insulation significantly affect the thermal resistance by conducting heat from one side of the insulation to the other. Although not as conductive as metal, the thermal resistance of wood and the cross sectional area of the wood furring penetration should be taken into account when determining overall R-values. See TEK 06-13B, Thermal Bridges in Wall Construction (ref. 9) for more information.

Closed cell spray polyurethane foam is typically installed between interior furring. The foam is applied as a liquid and expands in-place. Proper training helps ensure a quality installation. The foam is resistant to both air and water vapor transmission.

When using interior insulation, concrete masonry can accommodate both vertical and horizontal reinforcement with partial or full grouting without interrupting the insulation layer. The durability, weather resistance, and impact resistance of the exterior of a wall remain unchanged with the addition of interior insulation. Impact resistance on the interior surface is determined by the interior finish.

INTEGRAL INSULATION

Figure 2 illustrates some typical integral insulations in single-wythe masonry walls. Integral insulation refers to insulation placed between two layers of thermal mass. Examples include insulation placed in concrete masonry cores and continuous insulation in a masonry cavity wall (note that an insulated masonry cavity wall can also be considered as exterior insulation if the thermal mass effect of the veneer is disregarded).

With integral insulation, some of the thermal mass (masonry) is directly in contact with the indoor air, which provides excellent thermal mass benefits, while allowing exposed masonry on both the exterior and interior.

Multi-wythe cavity walls contain insulation between two wythes of masonry. The continuous cavity insulation minimizes thermal bridging. The cavity width can be varied to achieve a wide range of R-values. Cavity insulation can be rigid board, closed cell spray polyurethane foam, or loose fill. To further increase the thermal performance, the cores of the backup wythe may be insulated.

When rigid board insulation is used in the cavity, the inner masonry wythe is typically completed first. The insulation is precut or scored by the manufacturer to facilitate placement between the wall ties. The board insulation may be attached with an adhesive or mechanical fasteners. Tight joints between the insulation boards maximize the thermal performance and reduce air leakage. In some cases, the joints between boards are set into an expandable bead of sealant, or caulked or taped to act as an air barrier.

Integral insulations placed in masonry cores are typically molded polystyrene inserts, foams, or expanded perlite or vermiculite granular fills. As for the furring used for interior insulation, the thermal resistance of the concrete masonry webs and any grouted cores should be accounted for when determining the thermal performance of the wall (see TEK 06-02C, ref. 3, for tabulated R-values of walls with core insulation). When using core insulation, the insulation should occupy all ungrouted core spaces (although some rigid inserts are configured to accommodate reinforcing steel and grout in the same cell).

Foamed-in-place insulation is installed in masonry cores after the wall is completed. The installer either fills the cores from the top of the wall or pumps the foam through small holes drilled into the masonry. Foams may be sensitive to temperature, mixing conditions, or other factors. Therefore, manufacturers’ instructions should be carefully followed to avoid excessive shrinkage due to improper mixing or placing of the foam.

Polystyrene inserts may be placed in the cores of conventional masonry units or used in specially designed units. Inserts are available in many shapes and sizes to provide a range of R-values and accommodate various construction conditions. In pre-insulated masonry, the inserts are installed by the manufacturer. Inserts are also available which are installed at the construction site.

Specially designed concrete masonry units may incorporate reduced height webs to accommodate inserts in the cores. Such webs also reduce thermal bridging through masonry, since the reduced web area provides a smaller cross-sectional area for heat flow through a wall. To further reduce thermal bridging, some manufacturers have developed concrete masonry units with two cross webs rather than three.

Vertical and horizontal reinforcement grouted into the concrete masonry cores may be required for structural performance. Cores to be grouted are isolated from cores to be insulated by placing mortar on the webs to confine the grout. Granular or foam insulation is placed in the ungrouted cores within the wall. Thermal resistance is then determined based on the average R-value of the wall area (see TEK 06-02C, ref. 3, for an explanation and example calculation). Some rigid inserts are configured to accommodate reinforcing steel and grout, to provide both thermal protection and structural performance. When inserts are used in grouted construction, the coderequired minimum grout space dimensions must be met (see TEK 03-02A, ref. 10).

Granular fills are placed in masonry cores as the wall is laid up. Usually, the fills are poured directly from bags into the cores. A small amount of settlement usually occurs, but has a relatively small effect on overall performance. Granular fills tend to flow out of any holes in the wall system. Therefore, weep holes should have noncorrosive screens on the interior or wicks to contain the fill while allowing water drainage. Bee holes or other gaps in the mortar joints should be filled. In addition, drilled-in anchors placed after the insulation require special installation procedures to prevent loss of the granular fill.

EXTERIOR INSULATION

Exterior insulated masonry walls are walls that have insulation on the exterior side of the thermal mass. In these walls, continuous exterior insulation envelopes the masonry, minimizing the effect of thermal bridges. This places the thermal mass inside the insulation layer. Exterior insulation keeps masonry directly in contact with the interior conditioned air, providing the most thermal mass benefit of the three insulation strategies.

Exterior insulation also reduces heat loss and moisture movement due to air leakage when joints between the insulation boards are sealed. Exterior insulation negates the aesthetic advantage of exposed masonry. In addition, the insulation requires a protective finish to maintain the durability, integrity, and effectiveness of the insulation.

For exterior stucco installation, a reinforcing mesh is applied to reinforce the finish coating, improving the crack and impact resistance. Fiberglass mesh, corrosion-resistant woven wire mesh or metal lath is used for this purpose. After the mesh is installed, mechanical fasteners are placed through the insulation, to anchor securely into the concrete masonry. Mechanical fasteners can be either metal or nylon, although nylon limits the heat loss through the fasteners.

After the insulation and reinforcing mesh are mechanically fastened to the masonry, a finish coating is troweled onto the surface. This surface gives the wall its final color and texture, as well as providing weather and impact resistance.

BELOW GRADE APPLICATIONS

Below grade masonry walls typically use single-wythe wall construction, which can accommodate interior, integral, or exterior insulation.

Exterior or integral insulation is effective in moderating interior temperatures and in shifting peak energy loads. The typical furring used for interior insulation provides a place to run electric and plumbing lines, as well as being convenient for installing drywall or other interior finishes.

When using exterior or integral insulation strategies, architectural concrete masonry units provide a finished surface on the interior. Using smooth molded units at the wall base facilitates screeding the slab. After casting the slab, a molding strip, also serving as an electric raceway, can be placed against the smooth first course. The remainder of the wall may be constructed of smooth, split-face, split ribbed, ground faced, scored or other architectural concrete masonry units.

Insulation on the exterior of below grade portions of the wall is temporarily held in place by adhesives until the backfill is placed. That portion of the rigid board which extends above grade should be mechanically attached and protected.

REFERENCES

  1. Condensation Control in Concrete Masonry Walls, TEK 06-17B, Concrete Masonry & Hardscapes Association, 2011.
  2. Control of Infiltration in Concrete Masonry Walls, TEK 06-14A, Concrete Masonry & Hardscapes Association, 2011.
  3. R-Values and U-Factors of Single Wythe Concrete Masonry Walls, TEK 06-02C, Concrete Masonry & Hardscapes Association, 2013.
  4. R-Values of Multi-Wythe Concrete Masonry Walls, TEK 06-01C, Concrete Masonry & Hardscapes Association, 2013.
  5. International Energy Conservation Code. International Code Council, 2003, 2006 and 2009.
  6. Energy Efficient Standard for Buildings Except LowRise Residential Buildings, ASHRAE/IESNA Standard 90.1. American Society of Heating, Refrigerating and Air Conditioning Engineers and Illuminating Engineers Society, 2001, 2004 and 2007.
  7. International Energy Conservation Code and Concrete Masonry, TEK 6-12C. Concrete Masonry & Hardscapes Association, 2007.
  8. Energy Code Compliance Using COMcheck TEK 06-04B, Concrete Masonry & Hardscapes Association, 2012.
  9. Thermal Bridges in Wall Construction, TEK 06-13B, Concrete Masonry & Hardscapes Association, 2010.
  10. Grouting Concrete Masonry Walls, TEK 03-02A, Concrete Masonry & Hardscapes Association, 2005.

Earth-Sheltered Buildings

  • August 2018

INTRODUCTION

Earth-sheltering refers to using earth as part of a building’s thermal control system Earth-sheltered buildings can be either built into the earth or an existing hillside, or can be built above grade, and earth bermed around the exterior after construction. Earth-sheltered buildings can be built entirely underground, but are more often only partially earth-sheltered to allow adequate natural light into the interior. These buildings are most widely recognized for their energy efficiency, due to the insulating capacity of the earth and lower air infiltration through the earth-sheltered surfaces. In addition, earth sheltered buildings also offer superior protection from storms, insulation from outside noise, lower maintenance costs, and less impact on the surrounding landscape.

Concrete masonry is often the material of choice for earth-sheltered buildings. In addition to strength, durability, low maintenance and resistance to fire, soil gas, termites and other pests, the wide range of concrete masonry colors and textures provides an unlimited palette for the interior. Earth-sheltered buildings can also be constructed of conventional gray units, and easily finished with furring strips and drywall, since masonry is constructed square and plumb.

Earth-sheltered buildings are typically designed with passive solar features to further reduce mechanical heating and cooling requirements. In these designs, the concrete masonry absorbs solar energy, preventing interior overheating and providing heat after the sun sets. Types of passive solar systems and design considerations are covered in more detail in Passive Solar Design, TEK 06-05A (ref.1).

Many design and construction considerations for earth-sheltered buildings are the same as those for basements. For this reason, the reader is referred to Basement Manual: Design and Construction Using Concrete Masonry (ref. 2), which includes detailed information on structural design, water penetration resistance, crack control, insect protection, soil gas resistance as well as construction recommendations.

ENERGY EFFICIENCY

Earth-sheltered buildings save energy in several ways when compared to conventional structures. First, earth-sheltered buildings have a lower infiltration, or air leakage, rate. In homes, up to 20% of the total heating requirement can be due to infiltration. Almost half of that figure results from air leakage through walls other than windows or door openings. The earth covering effectively eliminates these losses.

Earth-sheltered construction also saves energy by reducing conduction heat losses through the walls and roof. The temperature difference between the building and the adjacent ground is typically much less than between an above grade structure and the outside air. In other words, the earth moderates the outdoor temperature swings, so that the earth-sheltered building is not subjected to as harsh an environment. In hot climates, the earth acts an a heat sink, helping keep the interior cooler.

CLIMATE AND SITE CONSIDERATIONS

Local climate can effect the practicality of earth-sheltering. Studies have shown that earth-sheltered houses are more cost effective in climates with larger daily temperature swings and low humidity, such as the northern Great Plains and the Rocky Mountains (ref. 3). In these locations, the earth temperature tends to be more stable than air temperatures, which allows the earth to act as a heat sink in hot weather and to insulate the building during cold weather.

Climate should also be considered when deciding on the type of earth-sheltered structure to build.

The site should be evaluated for water drainage. Choosing a site where the water will naturally drain away from the building is ideal. The finished grade should slope away from the building at least 6 in. in 10 ft (152 mm in 3.05 m) to carry surface water away. Where the topography is such that water flows towards the building, a shallow swale or trench can be constructed to intercept the water and divert it away from the structure.

In addition to the effect on water runoff, the site’s slope can significantly impact construction and design. Steeply sloping sites require much less excavation than flat or slightly sloping sites. South facing slopes work well in climates with a longer heating season, because the building can be easily designed with south-facing windows for direct solar gain (see also ref. 1). In climates with milder winters and hot summers, a north-facing slope may be preferable.

BUILDING MATERIALS

The choice of construction materials should consider the type of structure, depth below grade and soil type. Deeply buried buildings require stronger, more durable construction materials. The following is a brief list of recommendations for below-grade concrete masonry construction. Basement Manual: Design and Construction Using Concrete Masonry (ref. 2) contains more detailed recommendations as well as minimum requirements.

  • Concrete masonry units should be 8-in. (203-mm) or larger, depending on structural requirements. Use of unit shapes such as “A” or “H” facilitates unit placement around vertical reinforcing bars.
  • Type S mortar is generally recommended.
  • Joint reinforcement or horizontal reinforcing bars may be required to reduce potential shrinkage cracking and meet certain code requirements.
  • Grout, if used, must have a minimum compressive strength of 2,000 psi (13.8 MPa).
  • The concrete slab is typically a minimum of 2,500 psi (17.2 MPa) and 4 in. (102 mm) thick to allow the slab to span over weak soil areas without excessive cracking. Follow industry recommendations for subslab aggregate base and vapor barrier.
  • Backfill should preferably be free-draining material and should only be placed after the wall has gained sufficient strength and has been properly braced or supported.

TYPES OF EARTH-SHELTERED BUILDINGS

Earth-sheltered buildings can be constructed completely below grade or with part of the building above grade. An earth-sheltered building constructed completely below grade is referred to as an underground structure. More typically, though, the building is built partially or fully above grade, then earth is bermed up around one or more exterior walls. These bermed structures can in general accommodate more conventional building plans.

Underground Structures

Underground structures are most often designed using an atrium or courtyard design. This floorplan uses a subgrade central open area as the entry and focal point, and achieves an open feeling because it has four walls exposed to daylight. The structure is built completely below grade, typically on a flat site, and the interior spaces are arranged around a central outdoor courtyard. Windows and glass doors opening into the courtyard supply light, solar heat, natural ventilation, views and access to the ground level. Atrium/courtyard buildings are typically covered with less than 3 ft (0.91 m) of earth. Greater depths do not significantly improve the energy efficiency.

The atrium design provides minimal interruption to the natural landscape, good protection from winter winds and exterior noise, and a private outdoor space. Design considerations specific to atrium/courtyard structures are courtyard drainage and snow removal, as well as possibly limited passive solar gains, depending on the courtyard size and depth below grade.

Bermed Structures

Two general types of bermed structures are elevational and penetrational. Elevational floorplans have one whole building face exposed, while the other sides, and sometimes the roof, are covered with earth. The covered sides protect and insulate, while the exposed face, typically facing south, provides views, natural light and solar heat. This type of structure is typically set into the side of a hill, and tends to be the easiest type of earth sheltered building to construct, and therefore the most economical. Skylights and/or additional ventilation may need to be considered for the north-facing interior spaces.

Penetrational designs are built above grade, with earth bermed around and on top of it. The entire building is covered, except at windows and doors, where the earth is retained. This design allows natural light from all walls of the building, as well as cross-ventilation.

INSULATION PLACEMENT

Not all experts agree on the amount of insulation required nor the optimum placement around the structure, but two points are generally well agreed on:

(1) It is generally not cost-effective to insulate below the floor slab in an earth-sheltered building. Edge insulation is a good investment on walls that are not bermed.

(2) Insulation should be placed on the exterior side of the walls. Exterior insulation protects the waterproofing from abrasion damage and allows the thermal mass of the below-grade concrete masonry walls to contribute to the energy savings and indoor temperature moderation.

Because of the insulating effect of the soil, insulation is more effective for buildings located closer to the surface of the ground. Normally, for earth cover less than 5 ft (1.52 m) over the ceiling, the ceiling should be insulated. In most cases, it is less expensive to insulate the ceiling than to increase the roof capacity to carry the load of the additional earth.

Figure 1 shows four variations of insulation placement, with some general performance guidelines for underground buildings. Note that in some cases, insulation which is effective at reducing winter heat losses can actually be detrimental when cooling needs are considered. For this reason, it is important to match the insulation strategy to the heating and cooling needs of the building.

WATER PENETRATION RESISTANCE

All below-grade spaces are potentially vulnerable to water penetration from rainfall, melting snow, irrigation and natural groundwater, regardless of the construction materials used. For adequate protection, the following should be employed (see ref. 2 for a complete discussion):

  • Identify the water sources (precipitation, irrigation, groundwater and/or condensation) and address potential water entry points prior to construction.
  • Follow proper construction techniques and details
  • Provide drainage to direct surface and roof water away from the structure.
  • Install a subsurface drainage system to collect and direct water away from the foundation.
  • Apply damp-proofing or waterproofing systems to the masonry walls. A drainage board can also be used to drain water quickly and reduce backfill pressure.

OTHER CONSIDERATIONS

Earth-sheltered buildings require all of the considerations typically associated with basement design and construction, such as structural capacity, insect protection and soil gas protection. In addition, considerations such as adequate ventilation, egress and natural light may also be considerations for earth-sheltered structures.

Adequate ventilation must be carefully planned for earth sheltered buildings. Ventilation is the exchange of indoor air for outdoor air, and reduces indoor pollutants, odors and moisture. For buildings with low air leakage, such as earth-sheltered buildings, natural ventilation alone should not be relied upon. Instead, the building should utilize a mechanical ventilation system. ASHRAE recommends balanced air to-air systems with heat recovery for very air-tight homes (ref. 6).

The International Residential Code (IRC) (ref. 7) requires all habitable rooms to have a minimum glazing area of 8% of the room’s floor area, with minimum openable area of 4% of the floor area to provide natural ventilation. For earth-sheltered homes, if these requirements cannot be met using windows, doors, window wells and skylights, the IRC includes exceptions for homes with mechanical ventilation capable of providing 0.35 air changes per hour in the room or a whole-house system capable of supplying 15 ft3 /min. (7.08 L/s) of outdoor air per occupant. Supplementary artificial lighting may also be required.

In addition, bedrooms are required to have at least one openable emergency escape and rescue opening with a minimum net clear opening of 5.7 ft2 (0.530 m2). Window wells must have a horizontal area at least 9 ft2 (0.84 m2), with a minimum projection and width of 36 in. (914 mm). These emergency egress requirements may drive the building layout. Homes designed using an “elevational” floorplan, for example, tend to be long and narrow, so that the bedrooms and main living spaces are aligned along the above-grade wall.

Indoor humidity can increase during the summer, which can lead to problems such as condensation and mold if not addressed. Exterior insulation on the walls prevents the walls from cooling down to the earth temperature, but also reduces the heat sink effect for summer cooling. Mechanical dehumidification or air conditioning may be required to control indoor humidity levels.

REFERENCES

  1. Passive Solar Design, TEK 06-05A, Concrete Masonry & Hardscapes Association, 2006.
  2. Basement Manual: Design and Construction Using Concrete Masonry, CMU-MAN-002-01, Concrete Masonry & Hardscapes Association, 2001.
  3. EERE Consumers Guide: Site-Specific Factors for Earth Sheltered Home Design. U. S. Department of Energy, 2005.
  4. Earth-Sheltered Home Design. U. S. Department of Energy, http://www.eere.energy.gov/consumer/your_home/designing_rem deling/index.cfm/mytopic=10100.
  5. Forowicz, T. Z. An Anlaysis of Different Insulation Strategies for Earth-Sheltered Buildings. ASHRAE Transactions, Vol. 100 Part 2, 1994.
  6. 2005 ASHRAE Handbook Fundamentals. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 2005.
  7. 2003 International Residential Code for One and Two Family Dwellings. International Code Council, 2003.

Passive Solar Design

  • August 2018

INTRODUCTION

Passive solar design involves utilizing a building’s basic elements walls, windows and floors—to produce a comfortable environment with less reliance on mechanical heating and cooling. Passive solar systems can provide space heating, natural ventilation, cooling load avoidance, daylighting and water heating. The U. S. Department of Energy estimates that 30 to 50% energy cost reductions are economically realistic in new office design with an optimum mix of energy conservation and passive solar design strategies (ref. 1). In addition, most passive solar design strategies integrate well with active solar applications such as photovoltaics.

Concrete masonry plays a vital role in effective passive solar design, by providing thermal mass to absorb and slowly release solar heat. Without sufficient thermal mass, passive solar buildings can overheat and be uncomfortable.

It is most economical to evaluate passive solar strategies early in the design process. The rules of thumb included in this TEK are intended as a starting point for determining preliminary size and location for concrete masonry and glazing. As the design progresses, a more detailed analysis should be performed, preferably using software designed to accommodate passive solar interactions. Some appropriate software programs are briefly discussed near the end of this TEK.

PASSIVE SOLAR IN BUILDING CODES AND LEED

Renewable energy sources, such as passive solar, are typically not explicitly included in energy code criteria. Often, a passive solar building will comply with energy code requirements when the passive solar elements are neglected. Where this is not the case, for example where the prescriptive limit on glazing area is exceeded, most building codes allow compliance using an analysis based on whole building performance. For residential buildings three stories or less in height, Chapter 4 of the International Energy Conservation Code (IECC, ref. 2) describes the criteria for an annual energy analysis to demonstrate compliance.

For commercial and high-rise residential buildings, IECC compliance falls under section 806, Total Building Performance, or via Chapter 7 which references Energy Standard for Buildings Except Low-Rise Residential Buildings, ASHRAE/IESNA 90.1-2001 (ref. 3). Section 11 of Standard 90.1, Energy Cost Budget Method, is used for passive solar compliance. Note that a 2004 edition of ASHRAE 90.1 is also available, but the energy cost budget provisions are essentially the same as those in the 2001 edition. As for IECC Chapter 4, these sections define criteria for the annual whole-building analysis required to demonstrate compliance.

In the LEED program (ref. 4), passive solar systems are included under Energy and Atmosphere Credit 1, Optimize Energy Performance. This credit again references the energy cost budget method defined in Section 11 of ASHRAE/IESNA Standard 90.1 for demonstrating the building energy performance. Note that E&A Credit 2, Renewable Energy, applies only to renewable energy systems that generate power, such as photovoltaics, biomass and wind turbines.

ELEMENTS OF A PASSIVE SOLAR DESIGN

The components of a passive solar design are familiar parts of any building. In a passive solar building, however, these elements are carefully chosen, sized and located to work together to provide comfort. The function of each of these components is briefly described here. Some general guidance regarding sizing and location is included in the section Passive Solar Design Rules of Thumb.

Thermal Mass

Thermal mass in passive solar design provides three functions: it quickly absorbs solar heat to help avoid overheating when the sun shines; it stores the solar heat; and it slowly releases the heat to provide warmth after the sun sets. Concrete masonry walls and concrete paver floors are very efficient thermal storage mediums, and are commonly used in passive solar buildings to provide these functions. Masonry location and thickness are important to passive solar design, as are the conduction, specific heat and density. As these three properties increase, the heat storage effectiveness generally increases accordingly.

However, very high conductances should be avoided since this can shorten the time lag for heat delivery.

One important performance measure of passive solar buildings is the ability to maintain comfortable indoor temperatures. The amplitude of the indoor temperature swing is determined by the amount of effective thermal mass in the building. As the amount of thermal mass increases, the daily indoor temperature swing typically decreases.

Glazing

Glazing allows solar heat and light into the building. Choice of particular glazing products, sizes and locations will vary with the desired heat gain, cooling load avoidance and daylighting needs. These may vary within the building according to how the interior spaces are used. For example, because of glare, areas such as lobbies and atria may be more appropriate on a south-facing wall with a large amount of direct sunlight, than, for example, an office space.

Shading

Appropriate shading helps prevent solar heat gain during the summer. Shading may include permanent overhangs or porch roofs, moveable awnings, shutters, vegetation to shade east and west-facing windows, and/or limiting east/west glass.

Ventilation

Venting can rid the building of heat when the thermal mass is saturated. It can also provide outdoor air to cool the building when the outside air is cooler than the building’s thermostat setting, such as by precooling the building at night. Ventilation can be accomplished using natural ventilation or using an exhaust fan tied to a thermostatic control.

Types of Passive Solar Designs

Passive solar designs can generally be classified as one of three types, depending on where the solar heat is collected relative to where it is used: direct gain, indirect gain or isolated gain. The basic components are illustrated in Figure 1.

Direct Gain Systems

In a direct gain space, solar energy penetrates directly into the space where it is stored and used. Direct gain systems are the simplest to install since only windows and mass are required. Figure 1a shows the proper use of thermal mass in the walls and on the floor. Heat is collected and distributed by transmission through the windows, absorption at the mass surface, and convection and radiation within the room. Using sufficient thermal mass improves performance and comfort.

Indirect Gain

With indirect gain, a thermal storage material is used between the glazing and the space to be heated to collect, store and distribute solar radiation. An example is the trombe wall (see Figure 1b). A trombe wall uses a south-facing masonry wall faced with glazing placed 3/4 to 2 in. (19-51 mm) from the masonry. Heat from sunlight passing through the glass is absorbed by the masonry and slowly transferred through the wall to the interior space. Shading and/or ventilation are used to prevent unwanted heat gains during warmer periods. Vents at the top and bottom of a trombe wall are sometimes included to set up a convective current for passive cooling.

Isolated Gain

Isolated gain systems, such as sunspaces, collect solar energy in an area that can be closed off from the rest of the building. In addition to thermal mass floors, sunspaces typically use concrete masonry walls for thermal storage and as a heat transfer “valve” between the sunspace and the living or working space. Sunspace heat can be moved through vents with backdraft dampers to prevent improper flow. A fan, doors and/or windows can also be used to circulate warm air to the living space.

Because of the potential for overheating, care must be used when designing with sloped (i.e., overhead) glazings. Vertical glazings and pop-up skylights can be used with only a small decrease in performance. Vertical glazing is less expensive than sloped glazing, and overheating is more easily prevented.

PASSIVE SOLAR DESIGN RULES OF THUMB

Rules of thumb are useful early in the design process, as a first step in laying out the building and sizing the systems and materials. The rules of thumb listed below are most appropriate for buildings with skin-dominated heating loads, such as residential and small commercial buildings. Note that many of these design considerations involve compromises. For example, allowing maximum solar heat gain while minimizing summer heat gain. The designer should consider the specifics of the site and climate when evaluating appropriate passive solar design strategies. Software is particularly effective for evaluating these interactions for a particular building. General suggestions for successful passive solar performance include:

  1. Building orientation. Ideally, the building south wall should face within 15 degrees of true south. With this orientation, the building receives maximum winter and minimum summer heat gains. Between 15 and 30 degrees east or west of true south, performance tends to be reduced about 15 percent from the optimum.
  2. Buffer the north side of the building. Place rooms with low heating, lighting and use requirements, such as utility rooms, storage rooms, and garages on the north side of the building to buffer the other spaces. This can reduce the normally higher heat loss through north walls while not interfering with solar access.
  3. Match the solar heating system to the room use. Consider occupancy patterns when choosing a system: what are the heating, daylighting and privacy requirements of the room? For example, a bedroom requires privacy and needs heat after sunset, so a thermal storage wall might be the logical choice. A living room, on the other hand, needs daytime and early evening heat and has higher lighting requirements; therefore, a direct gain system or sunspace may be more appropriate.
  4. Include adequate thermal mass. For buildings with southfacing glass area more than 7% of the floor area, additional thermal mass must be included to absorb heat and maintain comfort. Thermal mass, such as concrete masonry walls and concrete paver floors, should be relatively thin (2 to 4-in. (51 to 102-mm) thick) to allow heat absorption and release within a 24-hour cycle; and should be spread over a large area to help prevent localized hot or cold spots.

Eight-in. (203-mm) fully grouted concrete masonry should be used if the wall is used as a north-south division wall separating two direct gain rooms. Such a wall can store heat on both sides, optimizing the mass storage. Do not fill the cores of these walls with sand, soil or insulation.

For trombe walls, the concrete masonry wall is typically 8 to 16 in. (203 to 406 mm) thick, depending on the desired time lag for heat distribution indoors.

Minimum recommended ratios of thermal mass area to additional glass area (i.e., south-facing glass area > 7%) are (ref. 5):

  • 1: 5.5 for floor in direct sunlight,
  • 1:4 for floor not in direct sunlight, and
  • 1:8.3 for wall and ceilings.

5. Distribute the thermal mass throughout the room. In direct gain systems, the primary collection mass is placed in direct sunlight. In addition to this mass, comfort is improved if mass is distributed evenly around the room because localized hot or cold spots are less likely to develop. Performance is relatively the same whether the mass is located on the east, west or north walls, or in the floor. The mass should be distributed over an interior surface area approximately equal to six times the solar glass area.

6. Avoid “insulating” thermal mass. Rugs or carpets in the solar collection space will significantly impact thermal mass performance. In general, an exposed strip of massive floor about 8 ft (2.4 m) wide provides a good floor collection area.

7. Select an appropriate thermal mass color. Masonry walls can be any color in direct gain systems, although the mass should be somewhat darker (0.5 < a < 0.8) than the low-mass materials. (Absorptivity, a, ranges from 0 to 1, indicating the percentage of incident solar energy that is absorbed. a = 1 indicates 100% absorption) The absorptivity of natural or colored concrete masonry falls in this range without paints or special treatments. Mass walls that are too dark (0.8 < a < 1.0), can result in high surface temperatures where surfaces are exposed directly to the sun, and less absorption elsewhere on the wall. Masonry floors, on the other hand, should be dark (0.7 < a < 1.0) to increase the absorption of the concrete pavers or masonry units and to counter the tendency of the heat to be released too rapidly to the atmosphere. A matt floor finish will maximize absorption and reduce glare. Thermal storage walls should be dark (a > 0.8) or coated with a selective surface material, such as a metallic film specifically designed to maximize absorption and minimize heat loss due to radiation back towards the glass. Materials without significant thermal mass, such as frame walls, should be lighter in color.

  1. Choose appropriate glass. Windows are typically rated by their solar heat gain coefficient (SHGC) and conductance (U-factor). Regardless of climate, the U-factor should be as low as possible (0.35 or less), to minimize conductive heat loss through the windows. For south-facing glass in most climates, choose windows with a SHGC as high as possible (0.6 or higher) to allow maximum heat gain during the winter, and rely on overhangs or other shading to limit summer sun. In cooling climates, such as south Florida, choose windows with a SHGC as low as possible.
  2. Use appropriate window shading. Windows facing within about 30o of true south can be shaded with properly sized overhangs. Figure 2 shows guidelines for sizing the overhangs to allow sunlight entry from about mid September through mid-March (software is also available for sizing overhangs). Off-south wall orientations reduce overhang effectiveness.

    East- and west-facing glass can be a significant source of heat gain and glare year-round, because of low morning and evening sun angles. Of the two, west-facing glass is more of a concern, because afternoons are typically hotter than mornings. There are several strategies to address these issues: limit the area of east- and west-facing glass; use wide overhangs (such as porch roofs; smaller overhangs will not be effective); use evergreens for shading; or use glass that blocks solar heat (although this may require different glass types for different walls of the building).
  3. Landscaping. Consider solar access and prevailing wind patterns when choosing trees and shrubs. Issues to consider include: shading of south-, east- and west-facing glass; channeling summer breezes; summer shading of the roof and paved areas; and blocking prevailing winter winds. Because leafless deciduous trees can block as much as 30% of winter solar energy, trees should not be placed where they block the south-facing windows in locations where significant winter solar heating is expected. However, in climates where summer heat is a significant problem, trees on the south-facing side may be appropriate.

SOFTWARE TOOLS

Software to evaluate passive solar buildings should include an annual whole-building analysis, and be able to correctly model solar gains and thermal mass. Programs such as DOE2 and BLAST are very comprehensive and well-documented. However, these programs require a high level of user expertise and can be cumbersome to use.

Energy-10 is a conceptual design tool focused on making whole building trade-offs during early design phases for residential and small commercial buildings (less than 10,000 ft2 (930 m2 ) floor area). The program performs an hourly annual whole-building energy analysis, including dynamic thermal and daylighting calculations. Outputs include a summary table, detailed tabular results and 20 graphical outputs.

EnergyPlus builds on the capabilities of BLAST and DOE2, with some additional simulation capabilities such as time steps of less than an hour. Input and output are via ASCII text files, although the program was developed to facilitate thirdparty user-friendly interfaces (see http://www.eere.energy.gov/ buildings/energyplus/ for available interfaces).

These programs are described on the Department of Energy website, http://www.eere.energy.gov/buildings/tools_directory. The website contains a list of over 300 building analysis programs, searchable by name, subject or platform. The site also includes information on program capabilities, input, output, user expertise required, how to obtain the software, as well as strengths and weaknesses.

REFERENCES

  1. Passive Solar Design. U. S. Department of Energy, www.eere.energy.gov/buildings/info/design/integratedbuilding/passive.html.
  2. 2003 International Energy Conservation Code. International Code Council, 2003.
  3. Energy Standard for Buildings Except Low-Rise Residential Buildings, ASHRAE/IESNA 90.1-2001/2004. American Society of Heating, Refrigerating and AirConditioning Engineers, Inc., 2001/2004.
  4. LEED for New Construction and Major Renovations, LEED-NC version 2.2. U. S. Green Building Council, 2005.
  5. Green Building Guidelines: Meeting the Demand for LowEnergy, Resource-Efficient Homes. Sustainable Buildings Industry Council, 2004.
  6. ASHRAE Handbook, Fundamentals. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 2005.

Concrete Masonry Residential Details

  • August 2018

INTRODUCTION

Concrete masonry homes reflect the beauty and durability of concrete masonry materials. Masonry housing provides a high standard of structural strength, design versatility, energy efficiency, termite resistance, economy and aesthetic appeal.

A wide range of architectural styles can be created using both architectural concrete masonry units and conventional units. Architectural units are available with many finishes, ranging from the rough-hewn look of split-face to the polished appearance of groundface units, and can be produced in many colors and a variety of sizes. Concrete masonry can also be finished with brick, stucco or any number of other finish systems if desired. Concrete masonry’s mass provides many consumer benefits. It has a high sound dampening ability, is energy efficient, fire and insect proof, durable and can easily be designed to resist hurricane-force winds and earthquakes.

WALLTYPES

Figures 1 through 3 illustrate a few of the construction options available for concrete masonry home construction, some of which are described in more detail below. Both top plate/anchor bolt and embedded strap anchor roof connections are shown and can be used interchangeably, along with several foundation types. See also 05 07A Floor and Roof Connections to Concrete Masonry Walls and 05-03A Concrete Masonry Foundation Wall Details (refs. 2, 3) for additional alternatives.

Single wythe walls offer the economy of providing structure and an architectural facade in a single building element. They supply all of the attributes of concrete masonry construction with the thinnest possible wall section. To enhance the performance of this wall system, two areas in particular need careful consideration during design and construction—water penetration resistance and energy efficiency. Design for water resistance is discussed in detail in References 4 through 6. A full discussion of options for energy efficient concrete masonry walls is contained in Insulating Concrete Masonry Walls (ref. 7).

The use of exterior finish systems lends itself to exterior insulation. Figure 1 shows an exterior insulation system, including a water drainage plane and stucco. Stucco can also be applied directly to the exterior block surface and used in conjunction with integral or interior insulation. Note that local codes may restrict the use of foam plastic insulation below grade in areas where the hazard of termite damage is high.

Figure 2 shows a residential wall section with exposed concrete masonry on the exterior and a furred-out and insulated interior. Concrete masonry can be exposed on the interior as well. In this case, integral insulation (placed in the masonry cores) can be used as required.

Figure 3 shows exterior siding with insulation installed between furring. Wood or vinyl siding, as shown, is typically attached using exterior wood furring strips which have been nailed to the masonry.

Cavity wall details are shown in TEK 05-01B, Concrete Masonry Veneer Details (ref. 8).

REFERENCES

  1. Annotated Design and Construction Details for Concrete
    Masonry, CMU-MAN-001-03. Concrete Masonry &
    Hardscapes Association, 2003.
  2. Floor and Roof Connections to Concrete Masonry Walls,
    05-07A. Concrete Masonry & Hardscapes Association,
    2001.
  3. Concrete Masonry Foundation Wall Details, TEK 05-03A.
    Concrete Masonry & Hardscapes Association, 2003.
  4. Water Repellents for Concrete Masonry Walls, TEK 19-01.
    Concrete Masonry & Hardscapes Association, 2002.
  5. Design for Dry Single-Wythe Concrete Masonry
    Walls, TEK 19-02B. Concrete Masonry & Hardscapes
    Association, 2012.
  6. Flashing Details for Concrete Masonry Walls, TEK 19-05A.
    Concrete Masonry & Hardscapes Association, 2000.
  7. Insulating Concrete Masonry Walls, TEK 06-11A. Concrete
    Masonry & Hardscapes Association, 2010.
  8. Concrete Masonry Veneer Details, TEK 05-01B. Concrete
    Masonry & Hardscapes Association, 2003.