Because the pressure difference between the inside and outside of a home during a hurricane creates negative air pressure so strong that it can literally suck the roof sheathing off the trusses or rafters, securely attached roof sheathing is important and it gets a discount. There are four levels of discounts, from “A” (weakest attachment, lowest discount) to “C” (strongest attachment, best discount).
Let’s start with the best, the “C” discount. Beginning in October 1, 2007, roofing contractors have been required to re-nail the roof sheathing using 8d (8-penny) ringshank nails at 6-inches on center when replacing a roof, which is the “C” category. These nails are longer than 6d nails previously required, and the rings around the nail provide extra holding power (withdrawal resistance). So, if you have a newer roof, you get the “C” discount. Also, homes built since the state-wide Florida Building Code took effect on March 1, 2002, meet the “C” standard.
