Steel roof decks are common substrates for low-slope membrane roof systems. Recent changes to recognized guidelines may affect the design and installation of roof assemblies that include steel roof decks.
In January, FM Global updated its Property Loss Prevention Data Sheet 1-29, "Roof deck securement and above-deck roof components," and several changes affect steel roof decks.
FM Global requires steel roof decks approved by FM Approvals be used for all insulated steel roof decks. In addition, deck spans, which are measured center to center, should not be greater than a deck's specific approval issued by FM Approvals. In some instances, roof decks' allowable deck spans according to FM Approvals are less than manufacturers' regularly published spans.