Thickness of OSB on Roof

Old 03-23-06, 09:03 AM
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Thickness of OSB on Roof

I am having a 2-story house built in the far west burbs of Chicago and have a question concerning the thickness of OSB used on the roof. The builder uses 7/16" standard. Should I inquire about upgrading to 1/2" or something thicker? By the way, the shigles used are 30 year. Also, what are the clips that are often refered to? Should I inquire with the builder as to the spacing of the roof framing or is this a standard spacing? Thanks!
Old 03-23-06, 10:53 AM
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Roof framing is almost always 24" OC. Your local building code surely specifies what the minimum size sheathing for roofs should be, and hopefully your contractor will be in compliance with that. A call to your local building inspector might set your mind at ease regarding what is acceptable in your area. Personally, if I use OSB on a roof, it's always 5/8. If 7/16" or 1/2" is used, h-clips are usually used, which are placed onto each sheet between the rafters, so that adjoining pieces of sheathing are tied together to prevent sheer movement under load. (like when you step there!)

Building codes that determine the size of roof sheathing consider the snow load in your area. Down south they can get away with thinner sheathing. But up north, the load potential grows. So heavier sheathing is usually a good idea. Its up to you whether the upgrade is worth the additional cost. 7/16 would be quite thin, IMO, and I'm suprised Chicago code would allow that. But then again, I'm not very knowledgable about codes!

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