High-Performance Building Envelopes Web Exclusive: The Devil is in the Detailing When Using TAFs Over ICF Walls
The explosive growth of Insulating Concrete Form (ICF) construction above grade has fueled a great deal of success in both residential and commercial construction. Because finishing ICF walls above grade is still a relatively recent development, greater consideration for issues like protection from the elements and fire performance is required to ensure optimal performance that will match the beauty of the finished product.
Because there are many types of ICFs - molded or extruded expanded polystyrene (EPS) and buried or exposed web designs come to mind - it is essential that considerable thought be given to the proper integration of the surface finish. Each may require a different solution, so choosing a finishing system should be decided at the design stage to ensure long term durability.
One of the most popular finishing systems favored by building and homeowners around the country is Textured Acrylic Finishes (TAFs). TAFs provide highly desired aesthetics, durability and a cost-effective way to easily convert ICF walls into structures with greater curb appeal.
TAFs consist of a fiberglass reinforced base coat that is covered with a textured acrylic finish. These finishes are available in a variety of textures, styles and colors, providing the owner with a multitude of exterior design possibilities. TAFs can be applied directly to ICF surfaces, or - if necessary to cover exposed form ties or increase the R-value - over an additional layer of EPS adhered to the ICF substrate.
Knowing that TAFs create greater sales opportunities for ICF structures and given the extraordinary aesthetic and performance values they represent to owners, it is important that ICF builders follow design details that have been developed by ICF manufacturers and TAFs manufacturers to ensure that the building performs as well as it looks. While these detailing considerations would be applicable to the selection of any finishing option, this article will focus on the application of TAFs over an ICF wall.
Detailing for Weather ProtectionAt penetrations, as well as at other terminations and transitions, proper flashing procedures need to be followed to prevent water penetration into the wall. Details are now available to help guide the design professional in effectively detailing ICF walls with TAFs.
Windows are, in many respects, the primary concern when it comes to detailing openings in the wall. Because there are so many types of windows available today, the appropriate detail for the window chosen needs to be determined at the design stage to ensure that the components are properly sequenced during the construction process. Once the windows are installed, it is probably too late to apply the appropriate detailing to ensure proper performance against water intrusion.
Detailing for Termites and Other InsectsIt is important that, where specified, the design protect the structure against termites and other insects. In areas where termite protection is necessary, code requirements, as well as the needs of pest control professionals, will need to be considered in the design. An inspection strip may be necessary to allow for proper treatment and yearly inspections. One method is to cut the EPS back to the concrete substrate along the base of the wall near the grade line.
Detailing For Non-Combustible CriteriaBuilding Codes have specific requirements for non-combustible walls using foam plastic as part of the exterior wall assembly. Two of these requirements include NFPA 285-Intermediate Scale Multi Story Fire Test (also known as UBC 26-9), as well as those of NFPA 268-Radiant Heat Exposure Test. To meet those tests it is necessary that the foam plastic be encapsulated with the reinforced base coat that is a part of the TAFs. Generally, this requirement is easily met by extending the reinforced base coat onto the exposed concrete along the edges of openings and other ICF terminations.
These steps need to be carefully considered and coordinated in the design stage of the project to minimize potential conflicts. These test requirements are part of the established building code and are required no matter what TAF finish material is ultimately used on the exterior of the walls.