Carpenters-Need info on OSB

[scgargoyle]

I built a shed out of OSB over 20 years ago here in termite/rot infested FL, and it's still standing! I just slapped it up and painted it. I wouldn't use it on a roof, though, but that's just me. Being an old-timey boat builder, I glue everything, in addition to nailing the daylights out of it- force of habit, I guess.

Speaking of roofing, the house I live in now had an interesting flaw. When I had the roof re-done a few years back, we could see that the metal drip edge was butted together, rather than over-lapped like you're supposed to. Needless to say, at every joint, the wood was rotted. This was the builder's own house! After I went all the way around the house repairing the deck, I also drove screws into all of the plywood edges. This being hurricane country, I'd like to keep the sheathing on my roof.

 

[herd]

The reason those older houses had 3/4'' roof boards for decking is that they used 1x6's mainly and disagonally for strenght. Yes, they were very strong but the problem is that over time, those 1/6's shrank and anywhere the roofer nail in between where two boards met, the roofing nail would eventually pullout and cause leaks. I think that's why soilid decking came into being.

Three quarters of an inch of anything it too darn much weight for roof decking, esp with an architectural shingled roof.

 

[studor]

Three quarters of an inch of anything it too darn much weight for roof decking, esp with an architectural shingled roof.

Jeez -- guess i had better rip off the rough sawn 1" planks on the roof of my cabin that are overlaid with 1/2" decking -- guess I will do it when the ice gets down to 3/4" inch or so in the spring -- course it has had about the same amount of weight on it for over 100 years
Properly raftered and fastened, 3/4 in sheathing makes an incredibly strong roof -- jmho

 

[bp fick]

The reason those older houses had 3/4'' roof boards for decking is that they used 1x6's mainly and disagonally for strenght. Yes, they were very strong but the problem is that over time, those 1/6's shrank and anywhere the roofer nail in between where two boards met, the roofing nail would eventually pullout and cause leaks. I think that's why soilid decking came into being.

Three quarters of an inch of anything it too darn much weight for roof decking, esp with an architectural shingled roof.

Plywood "came into being" as a way of producing a wood based product that would speed installation. Further, planking was growing ever more expensive as lumbering depleted the old growth forests. Shrinkage of the old boards was not the motivation for the invention of plywood or OSB products. Economics and manufacturing advancements were the reason.

Typically, when we describe roofs as having too much weight, we are describing the weight of too many layers of shingles for the underlayment to support. It is true that there is limit to the weight bearing ability of roof trusses. (also a manufactured product advancement)