Building Technologies Update for Multifamily Housing
Exterior Joining
Among the details to address on exterior walls, the means to join or connect cladding materials along joints, corners, and seams is worthy of design attention. Some products, such as masonry, have their own, well-established means of dealing with these details. Other products such as cladding panels or siding, require a separate trim product to deal with those transition areas. A design trend in this regard is to achieve clean modern lines that have become popular with younger generations and more urban multifamily projects. Hence, it has become common to see the use of extruded aluminum shaped trim pieces that make strong design statements while assuring the proper functioning of the cladding material.
Selecting aluminum trim can be based on its capability as a resilient material that can adjust and flex to meet the needs of building material expansion and contraction. From a design perspective, it is extruded in a wide variety of profiles, allowing for choice in appearance from recessed to pronounced. Manufacturers have made many different sizes available, allowing the trim to be used with multiple panels from different sources. And, it is available in multiple finishes including primed, clear anodized, and pre-painted.
Photo courtesy of Tamlyn
Extruded aluminum trim can be used in multifamily buildings to connect and secure exterior cladding in horizontal, vertical, corner, and transition locations while helping to create strong design statements.
Different aluminum trim profiles are available for different placement locations. Horizontal and vertical reveal pieces can be coordinated for a consistent appearance that maximizes or minimizes the lines between cladding panels. Outside and inside corners can similarly be treated to accent a corner condition or help it to blend in with the rest of the building. Transition pieces are available that connect special corner conditions and the junction of soffits to walls. When properly used and installed, these products not only provide for a complete, finished design appearance, they help with the overall performance and durability of the exterior cladding as well.
Stone Veneer
A fast-growing type of exterior wall treatment that has been specified on multifamily housing in recent years involves the use of masonry veneers. We have already discussed how they can be used as part of a wall system, but the details of the veneer itself warrant some further discussion. Masonry veneers are comprised of thin pieces of stone or brick but give the appearance of solid masonry without the weight or cost. Stone veneers provide a natural surface exposed to the weather that allows the finished building to emulate the great aesthetics of solid stone or brick but in fact they are non-structural. This means they install much quicker than natural stone or brick due to their simplified installation process with much less weight and potentially less cutting.
The options on the market for veneer masonry are broad and varied. Available choices range from a standard smooth or split face unit to veneers that look just like natural stone in varying sizes. The range of colors of the finished units is equally extensive and includes stone earth tone colors of grays and browns, a range of brick reds and oranges, and even white cast stone products. It is worth noting that these products have advanced considerably since they were first introduced several decades ago such that many have integral color worked into their makeup so the product color is consistent throughout each unit. The shapes and sizes are also varied to allow for details to be more authentically addressed.
For example, “L” shaped corner units allow for the appearance of solid dimensional stone while retaining the veneer qualities. Those qualities include the lighter weight, superior aesthetics, and integration into wall assemblies discussed previously.
Photos courtesy of Oldcastle® Architectural
Architectural stone veneer installs quickly and easily yet produces the finished look and durability that is needed for many multifamily buildings.
Single-Wythe Masonry
For larger building projects where full-size masonry is needed or desired, but budget constraints are tight, there is an alternative worth considering. Single-wythe masonry is made from concrete masonry but in an innovative sizing arrangement. The most popular choice for the best structural performance is for a 16-inch width and a 4-inch height. The width can vary from 4 to 8 to 12 inches depending on the overall look and economy desired. The broader depth thus eliminates the need for a separate CMU wall backup and gives it the name of single-wythe masonry. The one-step installation is a time- and cost-saving benefit that also eliminates the need for anchors to a framed wall assembly. It can be combined with insulated wall systems to provide increased energy efficiency, moisture management, and acoustical comfort or used with other standard construction systems.
Although single-wythe masonry is a concrete masonry unit, it is available in a range of colors that are formulated to match a variety of common and popular clay brick colors. These include reds, oranges, and even some yellows that are common for different design schemes. This type of masonry is very common in retail buildings due to the brick appearance coupled with the savings and durability of CMU. This also makes it very appropriate for mixed-use buildings that incorporate retail spaces with residential units. In some cases, it may also be appropriate for an entire multifamily building.
Images courtesy of Oldcastle® Architectural
Single-wythe masonry eliminates the need for a CMU backup wall but provides the look and aesthetics of clay brick.
Hybrid Storefront and Curtain Wall Systems
In some settings, curtain wall systems are preferred for low- to mid-rise multifamily residential buildings. In some cases, the design does not call for the high performance of a curtain wall system and a storefront system may be appropriate. A new ribbon wall style of system has become available that combines the best of storefront simplicity and the performance of a curtain wall into a single hybrid wall system. This design flexibility provides the option to utilize one system in multiple areas throughout a building, depending on the design needs of the project. Essentially, it is a pre-glazed product that combines exterior cladding, glass, and an integrated support system. It is intended to transfer all structural and wind loads to the building structure by resting on individual floor slabs while allowing for finished sections to cover the exterior edge of the slabs. In thermal simulations, this new product achieved U-factors on the order of 0.40 total with a 0.24 center-of-glass U-factor. Manufacturers make it available in 5-foot x 12-foot modules or custom modules, allowing for multiple design applications, from punched openings to mid-rise slab-to-slab elevations.
“This type of a hybrid between a storefront and curtain wall system,” says Richard Paulsen, storefront product manager for EFCO, “can be used in many storefront applications, as well as in many smaller curtain wall applications because of the ability to be glazed similar to a full curtain wall system.” With options available in sunshade mullions and slab edge covers, plus vent and entrance integration similar to that of a curtain wall, the whole system is customizable to meet specific project needs. The factory or in-shop pre-glazed option also provides a quality, economical solution for architects and glaziers, allowing them to save on labor costs and time associated with on-site glazing. Like many glazed wall solutions, both snap-together screw spline and shear-block fabrication methods are available.
Image courtesy of Pella EFCO Commercial Solutions
Hybrid ribbon wall systems combine the performance of curtain wall systems with the economy and flexibility of storefront systems for low- and mid-rise buildings.
Indoor Air Quality
Turning to the inside of buildings, an important aspect of green multifamily housing is indoor air quality. Research from the Environmental Protection Agency (EPA) indicates that indoor air is often more polluted than outdoor air. They note that volatile organic compounds (VOCs) are some of the primary pollutants found in indoor air, and formaldehyde is the most prominent VOC. Not only do these pollutants contribute to poor indoor air, they pose a potential health threat of respiratory illnesses, according to the U.S. Centers for Disease Control and Prevention (CDC). Formaldehyde has been well documented to be found in some building products, furnishings, and some everyday use items. As building designers we can reduce or eliminate VOCs from the multifamily building products we specify, but likely have very little control over some furnishings and personal products. Adding to the issue, multifamily construction is more tightly air sealed in the interest of energy efficiency but it also means that living units have a lesser ability to “air out” and release indoor air pollutants to the outside.
To help address this problem, there is now gypsum board available that is formulated to capture and convert formaldehyde into inert compounds, so that it cannot be re-emitted into the air. The effectiveness of this process has been tested in accordance with national standards and validated by third-party sources. It has been found to effectively clean the air even when used with multiple coats of water-based acrylic or epoxy paints and breathable wallpaper. Due to its inherent makeup, it can reside benignly in the background of the indoor space for years. Since it is still a gypsum board product, it can be installed and finished like regular gypsum board and is recyclable. On green building projects, this formaldehyde neutralizing gypsum board can potentially contribute credits for indoor environmental quality and recycled materials.
Graph courtesy of CertainTeed Gypsum
Independent studies have shown that levels of air pollutants are higher in the indoor air of many buildings than in the outdoor air around them.
Notice
www.certainteed.com/gypsum
www.efcocorp.com
www.echelonmasonry.com
www.tamlynwrap.com