Had our underslab inspection today and the ‘spector questioned my use of Stego Wrap 15 mil vapor barrier under the foam insulation. The accepted standard is 6 mil poly sheeting. Personally I think that’s a bare minimum and not really acceptable at all over the crushed gravel base I put in–walking on the poly to install and tape it, and then again while installing the foam insulation board would chew quite a few holes in it. The Stego is a way better product, very beefy and not damaged by all the traffic over it.
R506.2.3 reads “A 6 mil polyethylene or approved vapor retarder with joints lapped not less than 6 inches shall be placed between the concrete floor slab and the base course or….. ” There is no ASTM standard or any other reference to what “approved” means.
The tech person at Stego emailed me some docs showing their product meets ASTM E 1745 Class A standards, as well as two lesser standards. Tomorrow I’m going to give the inspector all of this documentation and I bet he’ll accept it, but in the meantime I’m wondering what folks here might know about this.
Replies
ain't building codes the "minimum" acceptable standard?
Eric
Let us know what he says.
The same IRC does not require any building wrap or felt paper under vinyl siding. what would he do in a case like that? Make you take it off?
We have one that will let a foundation guy just throw a little rebar in a footing and aprove it. Same guy goes nuts when I have a cold joint in a footing and five times the amount of steel, properly tied and on chairs. I had a PE stamp a drawing of my cold joint and the inspector grudgingly passed it.
Dave
"The same IRC does not require any building wrap or felt paper under vinyl siding. what would he do in a case like that? Make you take it off?"It depends what IRC he is using. The 2006 IRC requires a WRB under vinyl siding (and pretty much every exterior covering type).
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Ky hasn't moved up to the 05 version yet.
Dave
David,
I would think that you will be fine since the code says "or approved vapor retarder". If the Stego people can prove that their product has a perm rating of <1 than you should be fine. Since the code doesn't specify an ASTM I think they left the door open for alternate products.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
I ended up making a trip to the building counter today to resolve this. Took with me a piece of the Stego material, about 10 pages of documentation from the manufacturer, and a chunk of 6-mil poly for comparison. The Chief Building Official read thru the docs, looked at the sample, and gave me approval. It's not the first product that's in wide use elsewhere but has never been seen here.