The year 2020 will live in infamy for many reasons, among them is this record hurricane season. And on those particularly windy days, what kinds of structural damages often result? Most Florida residents have seen shingles fly by like high speed frisbees or palm fronds strewn across their streets and yards. But there are almost always an unlucky number of homeowners who have to contend with major roof sheathing failures that have debilitated their structures and let the storm inside. Roof corners, edges and sometimes whole swathes of roof sheathing are peeled away from the structure like a delicate clementine tangerine.
“Why”, you might ask. “Wasn’t this built to code”, you may contend. Well, times are a changing. The Florida Building Code 7th edition 2020 has officially been released and is set to take effect beginning December 31, 2020. Many jurisdictions will be adopting this new version of the code in 2021 and subsequently enforcing it.
Updates to the Florida Building Code tend to have far ranging effects since Florida is considered to be a leader in high wind design and mitigation techniques due to its exposure and vulnerability to hurricane events.
Among the updates in the FBC 2020 code revision, is an important set of fastening requirements that help prevent the damaging uplift forces that strip structures of their roof sheathing. In accordance with the new Code, ring shank fasteners with standardized dimensions and material properties designated in ASTM F1667 will be specified as the fasteners of choice.
Three common variants of these Roof Sheathing Ring Shank (RSRS) nails are typically specified. RSRS-01 (2-3/8” x 0.113”) nails, RSRS-03 (2-1/2” x .131”) nails and RSRS-04 (3” x 0.120”) nails. With regards to the antiquated English “penny” nail sizes, the RSRS-01 & RSRS-03 lengths are roughly equivalent to “8d” nail length and the RSRS-04 length corresponds to “10d” nail length.
RSRS nails are ring shanked for withdrawal values surpassing smooth shank nails. They also feature full round heads that increase pull thru capacities. These features help seriously mitigate two common failure modes of roof sheathing subjected to uplift forces. RSRS nails are available in the hot-dipped galvanized finish and 316 stainless steel for superior corrosion protection. The new Code requirements also mandate more stringent roof sheathing thicknesses based on project wind speeds as noted in the 2020 Florida Building Code Residential 7th edition Table 803.2.2.
While the Code provides some prescriptive tables for sheathing and minimum nailing requirements, it is always advisable to consult a professional licensed Structural Engineer to ensure the design and construction of your new structure can stand up to the elements of mother nature. Take these steps to make sure that the “Rise of the Roof Sheathing Ring Shank Nail” only happens in sales figures and never out the framing once it’s driven in.
Author: Enrique Fernández, PE