OSB or Plywood for floor and roof?


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Old 02-15-15, 03:20 AM
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OSB or Plywood for floor and roof?

Does it make a big difference if I use OSB instead of plywood for my floor and roof. Everything (joists) is on 16in centers and was wondering if 7/16 OSB would be fine for roof and floor. We are using felt before putting on roof shingles and was not sure if we needed to do the same before we installed the hardwood floor? Main concern is if OSB is good enough quality and if I am using correct thickness by using 7/16? Thanks for any help you can provide!
 
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Old 02-15-15, 04:07 AM
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Welcome to the forums!

IMO 7/16" is too thin for the roof but I think it is the new industry standard.
5/8" is the bare minimum for a subfloor with 3/4" being the norm. #15 felt should always be used under the hardwood [over the subfloor]
 
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Old 02-15-15, 04:08 AM
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Welcome to the forums! I would use no less than 5/8" OSB for the roof decking and 3/4" T&G Advantech (or equivalent) for the subflooring. 1/2" (or 7/16"actual) is not quite sufficient, IMO, for roof decking, although it is used a lot. It's a one time thing, and the expense is not that much more for better materials. 15# felt is needed for a layer between the subflooring and hardwood. Also, use PL Subfloor adhesive as well as ring shank nails to apply the advantech.
 
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Old 02-15-15, 04:27 AM
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OSB or Plywood

Thank ya'll for your responses! They will be very helpful as I continue my project. I am new to all this and I really appreciate the help with my questions.
 
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Old 02-15-15, 04:51 AM
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I will toss in another vote for Advantech at least for the floor. It's quite flat, is stronger than traditional OSB and is very moisture resistant.
 
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Old 02-15-15, 05:33 AM
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On the roof I would also be 8D ring shank full head nails, not clipped heads. May even be required by code in your area, they have slightly better holding power in a hurricane.
I also always use H clips between all the rafters or trusses.
Cheap insurance to prevent sagging, looks like poop to see a roof look like waves in the ocean.
I also always install drip cap on all outside edges.
Helps prevent water damage to the sheathing.
Read all the install directions on the shingles before installing!
High wind area, low slopes, steep slopes require a different nailing pattern and lay out.
Far to many times I've seen brand new shingles fail just because they where nailed in the wrong place.
 
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Old 02-15-15, 05:42 AM
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Good information-Thanks---I am in a high wind area on major slope!
 
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Old 02-15-15, 05:47 AM
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I am going to building supply and will check out Advantech---Thanks
 
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Old 02-15-15, 05:55 AM
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There is a direction to the osb as well, the long way across 6 spaces is better support.

Do your best at straightening (or sorting before they are installed) all studs, joists and rafters. And pay careful attention to the 16" on center dimension so all 4' x 8' material will land near the center of something to nail to.

There is a conflict with the dimensions of 4x8 sheets which is rarely mentioned. They are often exactly 4'x8' yet we can rarely get them installed tight enough so that they don't accumulate enough to no longer fall on a nailing point, especially true with tongue and groove. There are tricks, but you must be sure everything is square and if you start accumulating you must correct the 4x8 sheets and not move or add a nailing surface.

Bud
 
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Old 02-15-15, 07:14 AM
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Thanks---I am learning alot--this is definitely a great forum! I am so appreciative for all the info!
 
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Old 02-15-15, 08:35 AM
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Minimum 3/4" OSB for nail down flooring and it must be underlayment grade OBS. This is to prevent the staples or cleats from blowing out the other side. It is also the nature of OSB that it requires a thicker base for sufficient holding power. Plywood on the otherhand requires a minimum 5/8" for nail down on floor systems 16" on center. Advantech, however, is the industry standard these days for as it is stronger and more water resistant than other materials. It sometimes goes by different names (Home Advantage in big orange) and it will be a bit more pricy. But IMO, well worth the piece of mind that comes with using it over other materials.
 
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Old 02-15-15, 11:21 AM
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I am in a high wind area on major slope
Gotta be Sand Mountain. Only high point in Alabama Nice country.
 
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Old 02-16-15, 09:12 AM
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Everybody has helped out greatly! Sand Mountain is pretty and will be prettier if I ever get this done! Thanks
 
 

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