Hello everyone,
I have been building a 16 x 28 somewhat based on the Enchilada plans with 12/12 roof pitch, roof joists are 2x6's on 24" centers with collar ties on each rafter. The rafters sit directly on top of the 2x6 wall top plate and the exterior wall framing is 2x6x10s on 24" centers. I will be using a metal roof and need some advice on what thickness of roof sheathing to use. The metal roofing manufacturer says 7/16 OSB would be ok at a minimum but I would like to go with something thicker like 19/32 (5/8) CDX Plywood, but I was concerned about whether it might add too much weight to the roof structure. According to the Menard's website 7/16 OSB weighs 44 pounds per sheet and 19/32 CDX Plywood weighs 55 pounds per sheet so that's only an extra +- 250 pounds spread over the entire roof structure which seems fine to me but getting some advice on this before I proceed would be greatly appreciated!
Thank you!
I would go no less that 5/8" w/24 OC. OSB should be fine. That is what I used w/no problems. Additionally I used a synthetic underlayment.
I agree with 5/8 under metal to give the screws more pullout resistance, I personally prefer osb but ply is fine also, probably slightly higher pullouts.
This is the roof chapter in the codebook, you can check your rafter sizes and ceiling joist connections against your snow load. As long as that is within spec you are really good for any "standard" sheathing weight wise.
http://codes.iccsafe.org/app/book/content/VA/2012_VA_Residential_HTML/Chapter%208.html
Thanks, John for your input. I bought some synthetic underlayment today from the metal roofing supplier so we are on the same page with that.
Thanks, Don_P for your advice and for the link to the roofing load tables. I'm in South Mississippi so snow load would be minimal here. I will definitely be using 5/8 sheet goods, Now I just need to decide whether to go with OSB or Ply. Seems its raining here almost every afternoon lately, is one more durable than the other as far as getting wet once or twice before I get my underlayment on?
That's the main reason I switched to osb... it isn't supposed to happen but I've replaced too many sheets of ply after a single wetting. Swinging a sledge between the rafters wasn't my idea of fun. If it is properly glued this doesn't happen. I sort of think they were trying to "help" us decide to switch, making the osb better and the plywood worse.
Working alone, it took me a long time to finish my roof, and it got rained on plenty of times. It didn't seem to bother the 5/8" OSB I used.
That's what I needed to know, thanks for your help Don_P and Jay. I'm also working alone so it will probably get wet a few times before I get the underlayment on. Going today to get 5/8 OSB!
Quote from: MushCreek on July 06, 2016, 06:14:53 AM
Working alone, it took me a long time to finish my roof, and it got rained on plenty of times. It didn't seem to bother the 5/8" OSB I used.
Ditto! It was great when it stopped leaking once the metal roof was on. I had to sleep in a 24 foot trailer with my brother who snores and that all ended once the roof was done. :)