DIY ICF wall within a wall (interior) for dry-laid rubble foundation?

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pybyr

Minister of Fire
Jun 3, 2008
2,300
Adamant, VT 05640
I'm the "keeper" (word chosen deliberately, contrasing with owner) of a very handsome classic 1830+/- VT Greek Revival farmhouse which I acquired a dozen years ago in surprisingly unspoiled (some might say intensively-benevolently-neglected) original condition (badly leaking roof, no working central heat, failing septic- you get the picture).

Foundation, below ground, is randomly (but beautifully-workman-like) un-mortared random pieces of local low-grade slate. it leaked like a sieve until I put gutters on the house, which are now a maintenance item unto themselves. still lets in a TON of ambient moisture from the (damp heavy) surrounding soil in the summer months.

Foundation, above grade, is big blocks of granite, from the afore-mentioned slate up to the sills. There used to be an inner layer of handmade brick, to block drafts, but it had been perforated in so many places for ducts and wiring that it was a lost cause, and was removed to re-use the old brick for the visible parts of a re-built chimney.

basement floor, remarkably, is reasonably level poured concrete. A prior owner loved to mix concrete while drinkin' beer

sills and some of the floor joists have more than a little dry rot from the gravity-flow spring water system that was oozing all over the cellar in past years (and that is still a wonderfully reliable system, only now more carefully channeled and managed via poly tank, float valve, and cellar drain)

I've always hated to think about covering up the truly amazing workmanship of the random-stacked slate sidewalls of the basement and the hand-hewn granite from ground to sills.

but... I spend a lot of $ on electricity for a basement dehumidifier in the summer, and probably am losing heat out of the cellar like it's going out of style in the winter.

my ability to remain the keeper and carer-for this place obviously takes a hit if I cannot afford to live here....

I had an idea recently of trying to use DIY- ICF forms to build a wall-within-a wall, on the inside of the cellar, from the cellar floor to ground level, then pumping concrete between the ICFs and the rubble to stabilize the thole thing, and then using using the inside ICF wall as a support structure to take some load of the floor joists off of the sills (via vertical bracing from the top of the "poured" ICF "inner wall" to the floor joists), and then use sprayed foam insulation on the inside surface of the big granite chunks from the ICFs up to the sills.

I invite constructive suggestions and critiques

thanks
 
I have no idea on what you are trying to accomplish but sure would like to see photos of it just to understand/see/appreciate what you have.
 
Sounds like that may work. I just wonder about putting anything against the old foundation, especially with winter freezing. You may think about an inner wall of 2byes, pressure treated on the floor, plastic toward the outside, thermal board on the inside like R max. that would also shore up the floor joist. I'm only a backyard carpenter but I would bet there are local professionals who have done this many times in your area. Just ask around, there may even be some grant money to help out.
Ed
 
Have you ever just considered jacking up the whole house and (re) pour a concrete (std or ICF) foundation? I was supprised to hear how relatively cheap this was to do. A friend of mine just jacked up and moved a >100 farmhouse down the road and put if on a new foundation. The new owner told me that he did not even notice any cracks in the the plaster after the move.
 
my house has a main house, with a footprint of roughly 30x40, and a back/ kitchen wing with a footprint of roughly 20x30; about 10 years ago I had to have the foundation re-done under the back end because drainage problems + frost had heaved it in beyond redemption... I got 2 bids and basically went with the one who was most available and reputable. It wasn't cheap, and it also really disrupts living, yard, etc. So I really would like to leave as-is and where is, and just improve insulation in winter and ability to keep moisture out in the summer.

The random rubble foundation is in a way really beautifully crafted- must've been painstaking work to do it as well as someone did, mixing big and little random bits of slate to all fit together into vertical walls

I actually hate to cover it up- were it not for the heat loss issues in winter and moisture entry in the summer.
 
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