No foam allowed under drywall
user-6551155
| Posted in Building Code Questions on
My Brother and experienced home builder is doing a total energy upgrade and thorough renovation to a typical 2×4 stud frame Ranch Style house In The eastern panhandle of WV
The inspector will not allow any foam over the inside face of The studs Under the drywall, ( which we have done numerous times year ago with out dry wall “issues” years ago before WV Had regulations, )
Can anyone help us find good way To Get more than 3.5 ” of Fiberglass In the walls? The exterior is not being redone at this time Its alumainun siding.
The inspector just refers To The code and “Drywall must be glued an screwed to the studs.”
Thanks ,
Scott
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Replies
Hi Scott,
Here's an approach that one builder uses as his wall assembly for new homes. We've heard from a lot of remodelers who have adopted the strategy to mitigate thermal bridging and add depth to stud and rafter cavities for more insulation: Breaking the Thermal Bridge
There is still foam insulation over the studs, but there is a nailer for the drywall. I wonder if the inspector would accept gluing the drywall to the nailers. If he did, maybe you could use continuous foam, as you had hoped to do, and add furring strips at the plates and each stud to glue up the drywall.
Which county? Im in eastern panhandle as well.
I
Jefferson county Just in the edge or Ranson. But its not In Ranson,
Scott,
If "The Code" you are using is the International Residential Code (IRC), there is no such requirement. It looks like WV has adopted the 2015 IRC. While it is often difficult to change a building inspector's mind, I have found this approach to work on occasion:
Tell the inspector that you're really trying to understand this stuff and let him know that you appreciate his knowledge as a code expert. (The flattery part) Say you've tried to research the subject and you can't find any such requirement in the code. Then ask him to show you chapter and verse from the code that requires drywall to be glued and screwed. If he can't find the requirement, you can gently suggest that maybe there is no such requirement?
FWIW, I have attached the relevant table from the 2015 IRC. It shows that both screws and nails are allowable for attaching drywall. If you look at note A, it specifically states that nails are allowed without glue, if you use double nailing. Glue is not mentioned at all when using screws. And, there is nothing that requires direct attachment. The code only controls how deep into the studs the fasteners go to provide proper attachment.
The more than likely reason is , IF there isnt full exterior sheathing. They factor the sheetrock in to the racking resistance. Ive NEVER had a problem here with them passing it.
He should also allow perpendicular strapping which will increase thickness and reduce thermal bridging while providing a gypsum to wood attachment. It would work best with cellulose.
R702.3.2 apparently allows wood furring strips over any solid backing (or framing as above). I'd call foam (strips or continuous) a solid backing.
Good luck with trying to get an inspector to tacitly admit being wrong.