Interior insulation of concrete found’n
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Hello All,
I don’t know if I have lost my mind, but I seem to remember an article in Fine Homebuilding about a house in Vermont that was “the most energy Efficient house in America” or something like that. When I checked with my archives and also through Taunton, they couldn’t find anything but an article about a house in the South West. In particular I am interested in how the basement was insulated on the interior side. If I remember correctly they showed SM board glued to the concrete, then 1X4 strapping shot through the insulation into the foundation. Then the drywall was screwed to the strapping. If I could start from scratch, I’d use ICF’s but I am stuck with an existing foundation. What I am concerned about is vapour barrier and the length of the fasteners to be shot in to support the strapping.
Any thoughts?
Barn Guy
Replies
March 2004 issue #161 page74
Edited 1/12/2007 7:04 am ET by VAVince
Thank-you, thank-you, thank-you!!! I thought I had lost it. We are in the foothills of the Rocky Mtn's in Alberta, Canada and this looked like a good solution, but I couldn't find it in my back issues. I'll have to be more thorough next time.
Thanks again,
Barn Guy.
Hello again,
I just went through that article in detail and it did not have what I was looking for. They showed ICF's, but obviously in an existing foundation it can not accommodate that. Does anyone know of the detail I described previously? I can recall the illustration being in a Fine Homebuilding style and format.
It showed rigid foam being applied to the foundation wall with adhesive. Power and data lines would then be cut into the foam but I can not recall how the boxes would have been fixed. Then 1 X 4 strapping would be shot into the concrete, through the foam, to support the drywall. Does anyone have a comment on this style of construction? Is there a potential problem with moisture? How are the electrical boxes mounted?
The existing foundation is 5 years old with 2" rigid insulation below grade. In our climactic region our frost line goes down to as much as 6' below grade so we have a stepped foundation averaging 6' below grade.
Anyway, I would appreciate any help on this.
regards,
Barn Guy
You are probably thinking of this article.March 2005
The No-Mold Finished Basement
Rigid insulation is the key to a comfortable living space
Andy EngelIt is based on information from.http://www.buildingscience.com/resources/basements.htm.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Hello Bill,
I will dig up that issue today just to make sure I am not losing it, but the link you provided was exactly what I was looking for. Thanks a million and best regards.
Doug Stevens
I just moved from Alberta to BC. Finished a basement in Calgary and in Edmonton.
If I were to do another, my approach would be to PL some 2" Rigid Insulation with lap joints veritcally to the foundation wall. Tape the joints with Tuck Tape. This forms the vapour barrier. Moisture will escape above grade on the exterior. Frame a 2x4 wall infront of this, and insulate with R-12 Batts, with no vapour barrier. This should make it pretty comfortable.
Cheers,
Curtis
Hello Curtis,
That was my nagging feeling. Where did the moisture go? Even though we are dry here in Alberta and especially at our site, you have to be concerned with moisture. Again, thanks for the info.
Best regards,
Doug Stevens
I can't recall an article with this product, but I used Owen's Inso-Pink. Closed cell polystyrene over a block foundation. This product is 2' X 8' and is Rabitted on the edges(not sure if that's the term) but a 1X4 is insert into the foam every 24"
You glue the panels up and I used a Remington fastener to secure the 1"X4"'s in place. Don't use firring strips. I ribbed 3/4 CDX plywood. This makes a smoother or less twisted framing for the DW. As far as elec. boxes. Install most on interior walls, but when needed the boxes are glued (PL-400) to the foundation.Use 2" deep boxes and only on end runs, Run the wire behind the styrene "flat" against the foundation tapped in place.(you need the 1.25" clearance from DW rule)
This product is 1.5" and thus not a vapor barrier and does NOT use one. The installation does not harbor mold since it breathes. I would not however use it in an istallation, if the basement had a moisture problem. The foundation wall should also be very plumb and straight.
Hello,
Thanks for the info, although I have not been able to find the Owens Inso product anywhere, ...yet. Also, I am not familiar with the "CDX" plywood you mention. What is that product? Did you shoot or screw the plywood strips over top of the 1X4's imbedded in the Owens product?
Thanks again and best regards,
Doug
Sorry for the confusion the 1 X4's are not embedded in the poly. The edges of the poly panels are cut away so a 1 X4 can lay flush with the poly. This covers over the seams between the panels and allows a nailing scrip for the DW.
"CDX" is a builder grade plywood. I suggested that you cut the plywood into 3.5" strips instead of using a solid pine firing strip. Most firring strips even sorted from a pile are not worth using. They are very prone to twisting and will distort any DW you install over them.
The INSO-PINK I purchased was bought at a Big Box. In the Midwest we can find them at Menard's.
Thanks for the clarification. Yes, I always use ply for furring strips. In our dry (foothills of the Rockies) climate you can't possibly keep ANY lumber straight. I have moved over to using the new Weyerhauser LSL studs exclusively for ALL framing. Little waste, stays perfectly straight, nice clean corners and edges, great all around. Just heavy when you are framing large walls in one section. Also, you can't use a pheumatic spiker for any temporary blocking as the heat of driving in the nail fuses it to the resins in the stud and makes removal almost impossible. Anyway, thanks again, we are almost finished on our first test area with this method.
Best regards, Doug Stevens
We do this all the time. I'm definetly anti cold/vented crawls. We use 2" rigid glued to the concrete then for fire protection we glue 1/2" drywall to that. Havent had any problems. Dont forget to run 6 mil plastic on the floor and drop a heat in the crawl to keep the pipes from freezing.
I used this method on a house we just finished and the appraiser coiuldnt believe we went to the trouble. Her quote: "Your a builder? None of the builders around here care about that."
This is my first rental. I just stopped any frozen pipe calls at 3 in the morning and kept he floors from being overly cold. Worth every penny to me.
Dont forget the insulation around the rim joist. We use fiberglas for that. The inspector around here doesnt want to see any of the paper though (fire reasons again).
Edited 1/13/2007 2:25 pm ET by MSA1
MSA1
What kinda glue do you use and how much is required?
Its gotta be water based. I use either the foam board adhesive or the tube marked "projects". Usually we use between half and one full tube per 4x8 sheet of rigid.
Not necesarily water based.Look on the lable and see if it is approved for foam.I use PL Premium..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Good clarification. I guess I just assumed all foam board adhesive was water based. I just know that if you use the regular adhesive it supposedly (?) will eat the rigid away.