Preventing Water Penetration in Below-Grade Concrete Masonry Walls
Concrete masonry has traditionally been the material of choice for foundation wall construction. State-of-the-art waterproofing, dampproofing, and drainage systems applied to concrete masonry provide excellent protection from water penetration, ensuring protection for building contents and comfort for occupants.
Condensation Control in Concrete Masonry Walls
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.
Characteristics of Concrete Masonry Units with Integral Water Repellent
A concrete masonry unit’s characteristics are a function of the properties and proportions of the materials used, as well as the manufacturing processes. The unit characteristics do not singularly define the characteristics and performance attributes of a concrete masonry wall, but they certainly play a significant role in influencing those attributes. When used as part of a breathable exterior wall for an inhabited structure, or as a barrier for any conditioned or protected space, concrete masonry is expected to contribute to the water penetration resistance and moisture control of the wall assembly. Current model building codes include provisions intended to ensure that exterior walls provide adequate weather protection for the building (ref. 1).
Water Repellents for Concrete Masonry Walls
Water repellents are used on exterior walls to provide resistance to wind-driven rain. In addition, water repellents can also reduce the potential for efflorescence and staining from environmental pollutants, and enhance the color or texture of a wall.
Fire Resistance Ratings of Concrete Masonry Assemblies
Concrete masonry is widely specified for fire walls and fire barriers because concrete masonry is noncombustible, provides durable fire resistance, and is economical to construct. Chapter 7 of the International Building Code (IBC) (ref. 2) governs materials and assemblies used for structural fire resistance and fire-rated separation of adjacent spaces. This TEK is based on the provisions of Code Requirements for Determining Fire Resistance of Concrete and Masonry Construction Assemblies, ACI 216.1/TMS 216 (ref. 1) , which outlines a procedure to calculate the fire resistance ratings of concrete masonry assemblies. The 2014 edition of the ACI 216.1/TMS 216 is referenced in the 2015 IBC for concrete and masonry materials. This TEK is based on both prescriptive details and tables as well as the calculated fire resistance procedure, which is practical, versatile and economical. The calculation procedure allows the designer virtually unlimited flexibility to incorporate the excellent fire-resistive properties of concrete masonry into a design. Included are methods for determining the fire resistance rating of concrete masonry walls, columns, lintels, beams, and concrete masonry fire protection for steel columns. Also included are assemblies composed of concrete masonry and other components, including plaster and gypsum wallboard finishes, and multi-wythe masonry components including clay or shale masonry units.
Smart Applications for Concrete Masonry Systems
“Smart Applications for Concrete Masonry Systems” explores how concrete masonry units (CMU) function structurally and reviews their diverse applications in construction. CMU’s intrinsic values including durability, energy efficiency through thermal mass, fire resistance, ballistic protection, sound attenuation, and storm resilience are covered. It examines various applications from cavity walls and single-wythe structures to fire walls, stairwells, corridors, and public spaces, emphasizing how concrete masonry provides both functional benefits and aesthetic possibilities while offering superior performance.
Key Properties Related to ASTM C90 & Concrete Masonry
This course provides a comprehensive overview of concrete masonry units (CMU), focusing on the following key topics: defining what CMU is, typical concrete masonry wall assemblies, exploring ASTM C90 standard specification requirements and density-related performance properties, and reviewing moisture penetration resistance strategies. These strategies include flashing and weeps, integral water repellent, and crack control.
Core Performance: The 5 Ss of Concrete Masonry
Concrete masonry is commonly used for structural and architectural walls in buildings. Knowing the full extent of its applications and capabilities is important for designers to make resilient, sustainable, and cost-effective buildings.
The intent of this course is to provide a general overview of the properties and performance characteristics of concrete masonry walls. Attendees will learn about how to take advantage of and maximize the features and capabilities of concrete masonry units.
Heat Capacity (HC) Values for Concrete Masonry Walls
Heat capacity is a material property used to assess a wall’s thermal mass, and it is often used as a criteria in energy codes and standards. Thermal mass is defined as: the absorption and storage of significant amounts of heat in a building or in walls of a building (ref. 1). Wall thermal mass, such as that present in concrete masonry construction, tends to decrease both heating and cooling loads in a given building, thus saving energy. The amount of savings realized by incorporating thermal mass into a building’s design is a function of several variables. These include local climate, wall heat capacity, fenestration (window) area, fenestration orientation, fenestration solar gain, building occupancy load and other internal gains such as lights and office equipment. The most manageable approach to account for energy savings due to thermal mass is to relate the savings to the wall heat capacity and local climate.
Thermal Bridges in Wall Construction
Thermal bridging occurs when a relatively small area of a wall, floor or roof loses much more heat than the surrounding area. Thermal bridging can occur in any type of building construction. The effects of thermal bridging may include increased heat loss, occupant discomfort, unanticipated expansion/contraction, condensation, freeze-thaw damage, and related moisture and/or mold problems for materials susceptible to moisture. The severity of the thermal bridge is determined by the extent of these effects.