Metal Roof Design under new code?

[hotinhawaii]

Does anyone understand what the new code will mean for the installation of metal roofing? It requires roofing assemblies to take into account hurricane wind loads. Does this mean that there must be plywood under metal roofs, especially at the eaves? Chapters 15 and 16 reference this but I don't know how to determine if metal or plywood comply.

[hereonearth]

Excellent question and I haven't yet seen the references you mention. Here on the East side of the Big Island most metal roofs are installed on wood trusses without plywood, and spaced 4' apart. My guess would be add more roof screws!

[john the architect]

Metal roofs can be much better survivors in high winds. Although there are some exceptions. most are not shingles but panels, and it is harder to rip that off than small parts which are minimally attached. When I design, plywood or wood trusses are not considered as structural connection points. I go all steel with gnarly fasteners I can rely on drilled or bolted into high strength metal, not some laminated organic product. I like wood for furniture, however.

John Maloney
310.562.0362
johnmaloney3@me.com
Hawaii Architect AR8082
www.jmagreenbuilding.com