I am trying to interpret the HUD building code as pertains to my 2003 doublewide and the failure of the roof deck OSB! The roof is approx. 3 or4 in 12 slope with three tab shingles stapled on. My biggest question is the underlayment is some sort of 3 ply brown paper possibly felt with an embedded thread running through it. Between one of the layers is a very thin like sprayed on layer of like black paint as if to attempt to barely meet the asphalt criteria. The underlayment is not asphalt saturated as the ASTM 226 Type 1 states. Is anyone familiar with this underlay material as it does not appear to be water proof? The sheathing OSB is stapled on which makes reroof using conventional OSB and shingles reroof essentially impossible IMO! Any comments or suggestions will be greatly appreciated!
With "regular" building codes they tell you what to use to build with. They specify how many fasteners, what kind of fasteners, how big the studs need to be, what type of underlayment, and so forth.
With HUD code, they specify various performance standards, and allow engineers to use whatever materials in whatever combination they like, so long as they certify that it will meet the performance standards.
The only way to find out what your roof is made from is to contact the factory. If it was me though, I think I'd just tear off whatever is there, and replace it with standard felt and shingles. Or metal. Remember that one of the criteria that the original faces is being towed on the highway for up to 200 miles.