Masonry has been used successfully in building construction in the Northwest region (Washington, Oregon, and Idaho) for many decades as both the primary structural system and as a cladding material. Masonry has withstood the test of time not only because of its natural resistance to fire, water, impact, and organic growth but also because of its design versatility.
Historically, structural mass masonry wall systems such as that shown in Fig. i-1 were commonplace, primarily due to their superior fire- resistance, durability, and weatherability. Over time, such systems have given way to alternative structural/ framing materials and separate cladding elements. By definition, mass structures above-grade functions of walls, including control of water, air, heat, sound, and fire. Thus, replacing the mass structure increases the complexity of the wall design as follows:
Wall cavity and/or exterior insulation may be necessary for thermal and sound control.
An air barrier is necessary to limit the uncontrolled exchange of air—and consequently the uncontrolled exchange of moisture (primarily vapor), heat, sound, and pollutants that move with air—between the interior and exterior environments.
Moisture control is rethought to ensure that moisture-sensitive structural and insulation components are protected.
Traditional decorative and durable cornice and cornerstone elements and strategically located built-in drip edges were typical of mass masonry structures. These were also responsible for deflecting much of the water cascading down the face of these buildings. These design elements have been either eliminated or traded for more modularized and economized veneer units that, while reminiscent of historic mass masonry construction detailing, do not have the same water- deflecting characteristics. Fortunately, most veneer wall assemblies are able to accommodate the added moisture ingress due to a concealed drainage plane and flashings. The result is a similar material aesthetic, fire-resistance, and durability, yet a flatter and simpler appearance, such as that shown in Fig. i-2, that lacks the intrinsic ability to deflect water away from the masonry-clad wall face and away from areas most sensitive to water entry, e.g., wall penetrations such as vents, windows, and doors.
Though the evolution of the above-grade wall design has led to more complex overall systems, product selection, and code compliance than in previous years, it has also demonstrated the durable and accommodating nature of modern above-grade masonry wall systems to the local climate conditions of the Northwest region.
As a result, the focus of this guide is to provide comprehensive design and construction detailing information for 8 primary above-grade wall systems successfully used in the Northwest climate that are composed of clay or concrete masonry as an adhered or anchored veneer or single-wythe concrete masonry unit (CMU) wall application. The focus for each system is to clarify the overall above-grade wall building enclosure design as it relates to managing moisture (both liquid water and vapor), air, and heat transfer between the interior environment and exterior environment and to demonstrate the constructibility of these systems to provide long-term durability. Cladding considerations including attachment and installation methods are also addressed.
Each system within this guide is addressed specific to the Northwest region, including Washington, Oregon, and Idaho and considers local climate, codes, and building preferences and practices. The systems included within this guide have also been developed for application to occupied multistory, multifamily residential or commercial structures with typical indoor environments (e.g., ASHRAE 551–compliant spaces) in the Northwest region. Multistory applications of each system are recommended in the “Masonry Systems Comparison Matrix” beginning on page i-8. Although, some of the systems discussed within this guide may be applicable to structures with atypical indoor environments (e.g., natatoriums, fridge and freezer warehouses, unconditioned spaces, etc.), these applications are not the intended scope of the guide.
The information presented within this guide is not meant to be exhaustive of all system variations, product performance properties, or detailing approaches but rather represents a selection of the successful enclosure design and construction practices used in the Northwest region.
This guide is not intended to replace professional advice. When information presented here is incorporated into specification building projects, it must be reviewed by the design team and reflect the unique conditions and design parameters of each building in addition to conforming with local building codes, standards, and by-laws.
Fig. i-1 Historic Masonry Structure: Maple Leaf Gate, Seattle 1911
Fig. i-2 Contemporary masonry veneer structure, Wenatchee Valley
How to Use This Guide
This introductory chapter showcases the 8 primary above-grade wall systems that are the focus of this guide. This introduction also contains technical references and supporting information for general topics that apply to the featured above- grade wall systems.
Each subsequent chapter is dedicated to one of the primary above-grade wall systems and provides system-specific discussion, guidance, photos, and/or diagrammatic illustrations. Two- and three-dimensional details and cutaway wall sections are provided at the end of each chapter, summarizing the chapter content and illustrating its use in real-world-like applications.
The sections following the 8 system chapters contain additional information regarding thermal modeling parameters, product resources, and a glossary of terms.