Comments on: Foam Board Insulation R Values

By: Todd

Todd — Sat, 11 Feb 2012 13:33:24 +0000

Glad to hear the success! I hope you’ll become a Newsletter Subscriber and remain a member of our site. Good luck on future projects.

By: PaulV

PaulV — Fri, 10 Feb 2012 21:24:52 +0000

Todd,
The project took an unexpected turn. I found that I could remove the existing 12″ standing seam sheet metal roofing without damaging it. We removed the chimney penetrations and replace any damaged T&G. 30lb felt was used as a vapor barrier over the exterior side of the T&G. Next we created a 3 inch perimeter along the eaves and gable ends with 2 layers of 2×4′s. Sheets of 3″ polyiso was anchored with screws and covered with Feltex vapor barrier(feltex is similar to house wrap except that is rubberized on one side and is impermiable). Then we reinstalled the standing seam sheet metal panels with 3-3/4 screws. New sheetmetal facia and ridge cap was installed along with snow brakes. We also installed 4 fall protection anchors with D-rings exposed just under the ridge cap (2 on each side of the ridge). In addition we had a bit of snow brake left over so we installed three 4′ sections spaced 4 feet appart to make a permanently installed ladder on one corner of the roof to allow access to the peak. Overall, the project cost a whole lot less by reusing the existing metal panels. Had to purchase only 14 new sheets of standing seam. Only issue is that the new sheets obviously look newer than the 13 year old panels that were previously installed. Installed the newer panels (all in a row) on the side of the house that is not so observable. It resulted in an immediate impact on heating this winter. No more cold air cascading out of the loft area. The split mini heat pump heads now can handle the load.

Thanks for your advice.

By: Todd

Todd — Fri, 10 Feb 2012 16:53:33 +0000

Floating slab details vary greatly around the Country. You’ll likely need to work with your local building code official to work out the fine details. “Floating Slab” actually implies that you let the slab move up and down with the frost. Technically what your inspector is asking for is NOT a floating slab.

Most people in the industry consider each inch of foam board to be approx equivalent to 1 to 2 feet of artificial cover. So if the thickened slab is a foot below grade, and you have 2 inches of foam under it, you’ll likely defeat the frost.

Most thickened slabs are roughly 12 inches thick at the perimeter and 4 to 6 inches thick for the remaining slab. You’ll need to put the foam under the slab, then pour directly on top of it.

By: Mark Z

Mark Z — Tue, 07 Feb 2012 15:54:57 +0000

Hi we are interested in moving our double wide out of a park and on to our own piece of property. We live in upstate NY and we have to either have a 4 foot frost wall slab which I have been told is very expensive. I was also told by our town code enforcer that I can do a floating slab with high density foam board around it to protect the slab from the frost. Can you please tell me what the thickness should be and if it has to be on the bottom of the slab along with around the sides and it should all the the same thickness or the sides different from the bottom. Also how would I go about pouring the slab on top of the board? Thanks for any help you are able to give me.

By: mattgenton

mattgenton — Tue, 03 Jan 2012 04:22:08 +0000

hi to all at http://www.homeconstructionimprovement.com i thought i had sent this newyears eve but it didnt send so i have sent it again all things good for the new year to all of you
– matty g

By: Todd

Todd — Tue, 27 Dec 2011 22:33:40 +0000

That approach would work but some would argue it’s a bit of a fire hazard. A thermal curtain might be a good option as well.