Roofing, OSB or Plywood

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Old 03-07-19, 09:37 AM
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Roofing, OSB or Plywood

Gets to be about 110 here in summer, single digits in winter. Snow only an inch or two most years, ice is a real problem though. Should I use 1/2" osb or plywood (or 5/8? 3/4? 1 1/2??) on my new shed roof and the outside walls? Shed is 12x10 hideaway with a slant roof.

Plan to get the rafters up (still haven't penciled that one out yet), get the tar paper on the walls/roof, and shingle with heavies.
 
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Old 03-07-19, 09:45 AM
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I would not use 1/2" anything on a roof. 3/4" OSB or plywood would be the normal options depending on your joist spacing.
 
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Old 03-07-19, 09:50 AM
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boy howdy that 3/4 stuff is heavy, but if that's normal i'll get it done. Plan on 16" joist spacing so i can run insulation in it without cutting. Do I need to space them 1/8" apart (the plywood) or is it fine to butt them up.

Thanks Dave
 
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Old 03-07-19, 10:08 AM
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7/16" OSB is the norm around here for roof decking although some will step up to 5/8" OSB. Plywood is always better but OSB should be fine. What pitch will your roof be?
 
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Old 03-07-19, 11:20 AM
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Pitch won't be too steep. About 7' in back, 8' or so in front. Here's my idea, just trying to work out the details as i go.

 
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Old 03-07-19, 12:06 PM
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Yeah, 7/16" is standard minimum, you use h clips on the seams between rafters... and yes, 5/8 osb is way better. If you get 7/16, make sure it says it is rated for roofs... every once In a while you find some that specifically says it is for wall sheathing ONLY.

Everyone but plywood purists use osb nowadays. For best results, don't leave it exposed to the weather for long... get the felt and roof edging on asap.
 
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Old 03-07-19, 01:41 PM
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I used 1/2" osb on the shed I built about 8 years ago and have had no problems at all, even though it gets up to 2 ft of snow setting on it for long periods of time. It's also a Salt Box type shed like pictured.
 
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Old 03-07-19, 02:30 PM
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If you get 7/16, make sure it says it is rated for roofs... every once In a while you find some that specifically says it is for wall sheathing ONLY.
I didn't know that, is it stamped on the sheet of OSB or do you have to look elsewhere?
 
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Old 03-07-19, 02:31 PM
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Yes it's stamped on the sheet. (APA rating)

See footnote A
 
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Old 03-07-19, 05:49 PM
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I'm going to go with plywood just in case. i don't want any problems. So is 1/2" plenty for plywood? Sure would be easier to lift.
 
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Old 03-07-19, 09:10 PM
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Its okay, but if your rafters are 24" on center you will still want to use h-clips.
 
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Old 03-07-19, 11:29 PM
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For our garden shed, I spaced the rafters 24" apart and used 2x6s, with a 3/4" sheathing.

For our goat shelter, I spaced the rafters 16" apart and used 2x4s, with 5/8" sheathing.

Personally, I would never use 1/2" sheathing for any roof.
 
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Old 03-08-19, 07:13 AM
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Plan on 16" joist spacing
If you meant 16" rafter spacing, then 1/2 in. OSB or 1/2In. plywood will be adequate. Roofs around here are framed with rafters/trusses on 24" centers and sheathed with 1/2" OSB.
 
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Old 03-08-19, 07:40 AM
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yes, i meant rafters @ 16" using 2x6's. I plan to have this up longer than i'm alive so I want to make sure I do it right.
 
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Old 03-08-19, 09:08 AM
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1/2" CCA plywood 16"OC will be fine. It's structurally stronger than OSB too. When I built my 3-car garage I used 1/2" plywood on all the walls and roof for strength.
 
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Old 03-08-19, 11:06 AM
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If you are buying your sheathing at a traditional lumberyard, the person at the counter will be able to tell you what to use for your span. If you are shopping at a big box though, for example, you will find markings on APA approved products that tell you the allowable span. You will see two large numbers printed on it, something like 32/16, and, in this case, tells you that that sheathing is good for a 32” span as roof sheathing and 16” span for sub flooring.
 
 

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