I am way up in the Northwoods. I started insulating the inside of a basement (no insulation on outside of poured concrete walls) and planned to use a total of 5 inches of Styrofoam – one inch glued to the concrete and 4 inches in a stud wall. I was advised by a builder that I should not use any insulation within four feet of the floor. This is to allow some heat to go into the frozen ground outside the foundation. The theory is that the frozen ground will expand and cave the walls in. When the house was built, it was backfilled with sand. The soil in the area is mostly clay. Does this advice seem sound?
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looked it up on a map... couldn't find "way up in the Northwoods"
that would be the north end of the island where i live
how deep is your foundation below finished grade ?
what is the frost depth in your area ?
maybe he's right, maybe he's misinformed
Edited 1/22/2005 4:17 pm ET by Mike Smith
My location is Northern Wisconsin. The foundation is four feet below grade on one side and seven feet on the opposite side. Frost depth is normally four feet.
your frost depth and foundation are about equal... not a good thing...
i think that the backfilling with sand will allow for any ice crystals to expand without displacing the backfill and creating undo pressure on your foundation..
i would go ahead and insulate as you were going to.. you might want to spray the walls with a borate solution ( like BoraCare ) before you cover them up with the foam..
also.. on your stud wall.. i'd use a PT shoeMike Smith Rhode Island : Design / Build / Repair / Restore
Mike,
Do you spray the Boracare with a garden type sprayer? How much do you dilute it? Even at 1:1 that stuff is thick! Great product, though.
Thanks,Billy
in normal applications i dilute 2:1... in this case i might go 1:1.. or do 2 applications of the 2:1 with a day in between.. depends on how nervous i was
BTW ... last time i bought BoraCare i think i paid $125 for a gallon... what are you paying ?Mike Smith Rhode Island : Design / Build / Repair / Restore
I got it for ninety something by buying four or five gallons at once. I diluted to 4:1 with hot water to make it easy to spray from the garden sprayer and used two times in two days. This was from some of their instructions
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Last time I paid about $95 over the internet. It looks like the price has come down a little:
http://www.pestcenter.com/diy/content/catalog/showitem.asp?fldAuto=80
http://store.doyourownpestcontrol.com/cgi-bin/pestcontrol.storefront/EN/addtobasket/I065
Billy
thanks... i've still got a gallon left from my last job.... i wonder what the shelf life is.. i'm guessing forever ?????Mike Smith Rhode Island : Design / Build / Repair / Restore
I guess it lasts until the mold gets to it... I never thought about the shelf life on the stuff... You're right, it's probably darn near forever...
Billy
Mike:
Thank you for the advice. I think I will back off a little on the thickness of the insulation.
AndrewV