NRCA recently released The NRCA Roofing Manual: Metal Panel and SPF Roof Systems—2008. Because a majority of SPF roof systems are installed as re-cover roof systems, 38 new details—of the 100 construction details in the manual—are specific to the application of SPF as a re-cover roof system. One such detail is SPF(R)-3A, "Base Flashing with Existing Surface-mounted Counterflashing at Concrete Wall for SPF Re-cover."
Before applying SPF, properly prepare the existing roof membrane and insulation, meaning make sure surfaces are dry and free of substances that could inhibit the SPF's adhesion. Additionally, adequately secure the existing roof system to the primary substrate and/or roof deck for uplift resistance. It may be necessary to take a test cut in the existing roof system to determine its attachment method.
Because an SPF re-cover roof system needs a secure substrate, the existing membrane flashings should be removed or secured if they are loose. Depending on the substrate type, it may be more realistic to remove loose flashings instead of fastening into a concrete or masonry substrate. Also, the existing sheet-metal counterflashing should have its lower portion removed, and its upper portion should be adequately secured. It may be prudent to remove the entire sheet-metal counterflashing. At a minimum, the existing sheet-metal counterflashing, if not partially removed, should be re-secured to ensure a stable substrate for the SPF application.
Detail SPF(R)-3A from The NRCA Roofing Manual: Metal Panel and SPF Roof Systems—2008
It is important to note the "A" designation in Detail SPF(R)-3A. The letter identifies NRCA's order of preference for addressing specific detail conditions. Detail SPF(R)-3, "Base Flashing for Wall-supported Deck" depicts NRCA's preferred method of addressing base flashings for SPF re-cover roof systems. Detail SPF(R)-3A is an alternative detail NRCA also considers acceptable based on the limitations described in the detail.
I encourage you to use the SPF re-cover details in The NRCA Roofing Manual: Metal Panel and SPF Roof Systems—2008 for SPF re-cover projects.
James R. Kirby, AIA, is NRCA's associate executive director of technical communications.
COMMENTS
Be the first to comment. Please log in to leave a comment.