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Discussion Starter · #1 ·
Hello! Basement air sealing and insulation advice needed!
I have a 1903 foursquare in central Brrrmont on a mortared stone full basement foundation with slightly younger addition over crawl with perhaps no real foundation (appears to have been built like a "pole barn" -- posts on flat stones on the ground -- no access -- need to open up the floor in the spring).
The basement back wall and "floor" were blasted out of solid ledge, parts of floor appear to be below water table (puddles fill w/in several minutes of pumping out on a dry day) -- planning to fill low areas with crushed slate, then vapor barrier. Parts of the sill are rotted, especially between the basement and crawl --
I need to seal this up enough to get through the winter with a very limited budget --
It seems spray foam would be a good solution, but should it be left off the areas of sill that need replacing, and if so, what should be used to seal those areas?
 

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Pictures would help a lot---I don't think foaming the areas that need repairs is a good idea.

removing the foam will add a lot of time to the repair---I'd use something easy to remove in those spots.
 

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there was a guy in barre pumping foam 30yrs ago,,, by now there must be many more OR are you thinking buzz-bomb cans of foam :huh: if it were our home, i'd be spraying the walls &tear out what was in the way when it cam time to make repairs - just don't forget to document WHERE you need to repair :no:
 

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You could use XPS to insulate the foundation. After some good pictures that show the worst of the worst, we can go from there for suggestions. The first thing, would be to tuck and point any loose mortar joints, before doing anything with the insulation, same as taking care of any problems on the outside of the foundation.
 

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Discussion Starter · #6 ·
Thank you for all the prompt response and sorry for delay -- photo trouble --
The mortared foundation wall is in good shape and is all below grade. Above grade on 3 sides the foundation is capped with approx. 24x24x48 inch granite blocks [photos 1,2]; the back wall (blasted ledge) [photo 3] is in-filled with rubble under the sill of the original back wall of the house, with penetrations to the crawl under the addition [photo 4] for waste stacks and other obsolete plumbing (replacing all this in a manner to avoid running through inaccessible crawl).

Plaster on lathe was installed 2 inches in front of the granite blocks [photos 1,2] from under the sub-floor down to a few inches below exterior grade, apparently as a method of air sealing; foil-faced fiberglass (still in pretty good shape where intact) was nailed on over the lathe -- planning to remove all this next week to see the condition of the sill all way around.

In areas where sill is in good condition, I was thinking I could use canned foam (Great Stuff or similar) to seal/fill gaps between blocks/sill/subfloor and generally stuff any air leaks, but then what? Fiberglass bothers me because of the dampness, but rigid foam will not conform to the rough walls. Sprayed foam seems like the best idea in the long run, but along with future access to currently rotted sill, I am also concerned about trapping moisture against the good sills since exterior grading also needs improvement.

-- what is XPS?
-- any and all advice appreciated.
 

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At this point, I would look at either placing Roxwool or sprayfoam on the underside of the living space. To make that area habitable can be done. As for XPS not conforming, you place it like a wall, with 2x4 Pressure Treated framing. If done correctly, it will hold and make it a little warmer. Great Seal is good, but not correct for the job. Tiger Foam is pricier, but can be used for air sealing.
 

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Discussion Starter · #9 ·
Thank you very much for the input --
If the floor is insulated and the basement remains drafty, I believe the water meter, supply and waste lines will need to be insulated and Frostex taped (the house was drained last November when foreclosed on, but not before most supply lines burst and 2 toilets and a couple traps cracked -- I first saw the place in Feb. and it was about 20 degrees in the basement) -- there is no heat-producing appliance in the basement, just an electric water heater -- I was hoping to follow local weatherization advice to seal the sill and all attic penetrations to reduce "chimney effect" and maintain the basement above freezing -- but that may not be feasible before the sills can be repaired --
 
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