Just how effective is rigid insulation around the perimiter of a poured concrete foundation? Its done regularly here in the northeast, but what are the reasons for it? Does it prevent frost problems? Are there noticable savings in the annual heating and cooling expenses? I’m asking this because I’m trying to decide if I should insulate the foundation on a workshop I am building.
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foundation insulation in theory is great.. in actuality, it's a joke .. and a bad one at that..when they started insulating found's in the early '80's they went from footing to sill and stuccoed the top portions that were above grade...
baseballs, lawnmowers , etc. played hell with it , so people cut it off at the grade line..SOMEHOW..it became accepted by code..
so now the insulation goes from footing to grade where it does the LEAST amount of good..the most heat loss in a foundation is in the exposed portion where the outside temp is design temp (20 deg F here in RI).. go down a foot and the cold side is about 30 deg.. go down to the footing and the temp is about 45 deg.
so the expense of the insulation is not protecting the top exposed portion...
in addition, all foam products support vermin.. ants, larvae, and termites.. except the foam products that are treated during manufacture.. (Performguard EPS) so they also are putting the structure at risk..
in the south, foam products are not alowed unless they are treated.. so the insulated concrete foam form companies use Performguard products..
here in the North .. the inuslated conrete forms are untreated.. too bad..
so .. bottom line.. you can get a great foundation with foam insulation.. but 90% of them are being built wrong..
but hey, whadda i no ?
Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike,
Read your reply regarding insulation. I am building a small addition in the very near future . My plans call for block foundation with a crawl space. I , like many others, am interested in the foam insulated forms. Is there a better alternative? Right now I am planning on insulating as best I can between the floor joists and not insulating the foundation itself. My sub is not crazy about using the forms. Your thoughts are appreciated.
/s/ Manny
Manny.. where do you live ?
I've looked at ICF's about 4 times now.. but they were cost prohibitive.. and none of the MFR's around here were doing Performguard .. as i've said before.. the only oam products i'll use now are EPS with Performguard...too many of my old jobs with foam near the ground or on the exterior are now safe havens for ants, termites and larvae..
we've been insulating the inside of our crawl spaces and full foundations with insulated panels.. this one is a 3" Performguard bonded to 1/2" OSB...
tried to load a pic.. but it says i'm outta space..
this site sucks so much....Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike, thanks for the advise. I live in Morristown, in northwest New Jersey. I will take your suggestion and utilize the three inch insulation and OSB.I am building this addition myself. I am not a carpenter, by trade, but in the course of owning my 75 year old house for 11 years now, there is not much that I havent had to do. I am looking forward to the challenge.
Thanks again,
Manny Ayers
In my part of Alaska, it is the norm to insulate the entire building, including the exposed and unexposed foundation. 2 inches of blue board is typical and if someone is doing a good job, is covered first by PT plywood (to prevent it from getting bashed) and then by "Z-fold" galvinized metal that tucks under the siding and goes over all exposed PT plywood covering the foam.
Ants? None to speak of up here. Nor termites, snakes, diseases in ticks, or West Nile Virus. Just mosquitos and bears.
From what I can remember, something like 70% of the buildings heat loss to the slab is lost at the edges. This is their argument for requiring form insulation. My question is, what % of a houses total heat loss is lost to a slab? If this is a relatively low number, how much heat loss would you prevent with a r-5 product, and is it worth the expense and living with the downside of it's presence on you house.
Here in western N.C. we are required to have it, not for frost protection our footers are only 12" deep, but for heat loss. We don't have a real frosting, just a sort of temporary crusting, wait a few days and it's gone.
Installation of it and it's cement coating is a real pain in the back, everything is done at ground level with you bending over.
IMHO spend your money and time insulating better or thicker. Lastly, my termite spray outfit will not give me a warrantee on performance because foam is on the slab.
old lou.. it makes sense on upper slab upper wall.. but here they just don't use it at the top... crazy Mike Smith Rhode Island : Design / Build / Repair / Restore