Over Wintering Crawlspace Foundation
I realize it is now closer to spring than fall, but I am trying to plan ahead. I have a ton of site work and road building work to do and will be lucky to get a foundation in before next fall. And I would not be working on the project through the winter.
I will be building a crawlspace foundation in a high ground water area on clay to sandy loam ground. I fear placing the foundation in the fall and leaving it over the winter. The fear is that the soil will get saturated and without a heated structure above it will freeze and heave the foundation.
IS this a legitimate fear?
I have been told if I build the floor deck and, of course, protect it from water I should have no problem. IS this right? It seems to me that the floor deck would do nothing to keep the soil under the footing from freezing.
Any suggestions.
Replies
footings below frostline
The footing depth is supposed to extend below the frost line, so the foundation won't heave.
The concern I would have is an ice lens inside the foundation walls cracking them, or worse toppling them.
Using clean well draining gravels for the interior backfill, and get something on it to keep water from falling into it will all help.
"extend below the frost line,
"extend below the frost line, so the foundation won't heave. "
That is true on a finished or burried foundation, but whilke ti is left open to the winter air, one side of it is not that deep so it can freeze.
Typical here is bales of hay with plastic over them as cheap insulation
Yes I have heard of the issue of a fondation filling with water, freezing, and then blowing out the foundatin walls. Another reason for building the subfloor for over wintering.
With regard to building the footer below the frostline, you seem to be ignoring the fact that the interior side of the foundation is exposed to a lesser depth (ie not backfilled). This is the issue.
Thanks for your thoughts
That deck over will buffer things by about ten degrees
IS that ten degree figure an educated guess or is there so science behind the figure.
In either case I am not sure ten degrees is enough. In the area of this proposed build I had a slab poured in a pole barn on top of 8 to 10 inches of crushed rock. The building is fully enclosed (all be it a larger enclosed space than a crawlspace with deck) and the slab heaves every winter. Obviously water gets into the gravel under the slab and freezes. This could be a worse case than a crawlspace situation since water comes off the roof with out gutters and no perimeter drain and as such water can migrate freely uder the slab. A crwalspace would have a perimeter drain and hopefully keep the earth under the footer drier thsu affording less heaving. Still GOT QUESTIONS.
The Hay bail idea has merit, but would have expense, and be a mess, and would not work if I wished to build teh deck.
???
Do, where you been keeping yourself?
Look at the changes since you been gone...................
Heck, you could have been gone since yesterday,
that's how fresh this new place is.
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What are your plans for the crawl? are you going to pour over it or just leave it stone?..................or dirt? ...........or what.
And please give your location, so it isn't mystifying.
thanks.
"IS that ten degree figure an
"IS that ten degree figure an educated guess or is there so science behind the figure.'
Neither - it is years of experience in northern climates.
Hay = a mess?
Not compared to rebuilding the foundation of building on one ruined by frost
The swamp is the killer.
Maybe.
You say you are planning on placing a couple inches of foam inside the crawl?..............................nope, you mean on the crawl wall right?
I've heard of placing below grade, foam flat out maybe 4' above a shallow footing to keep the frost from going deeper. What depth will your footing be on the interior of this crawl? Exterior also if you haven't mentioned that.
Maybe just maybe (and that's alot of maybe since I'm no where near Northern Idaho (you grow potato's there?), this foam over shallow footing would work. Couple that with an active drainage (you got power there?) .
What do the locals think about it?
do, do, do.........
I don't know that lower heating bills is the way I heard it. Shallow footing use is how I remember it.
We dug here in July, footing and block done maybe end of august. I remember little else, except closing in the second floor walls (roof already on) in the snow. Windows went in sometime in the winter-used a small propane heater to work with once it was closed in.
I ran interior drains around the perimeter and along the footings of the interior mid walls. This drained the swimming pool effect after block and serves as a passive radon drain now.
You got radon there?
Give any thought to draining the interior as well? There's your passive draining of the inside.
Or, follow everyone in the area's lead-build when it's buildable.
Took me a yr and a half, nights and weekends-didn't shingle it, didn't drywall it. Had some help framing the second floor and roof. Some weekend help from those that owed or wanted a favor.
You got a job?
I worked Union. 4pm came-see ya. Nothin' to it. If you're not old.
Well if the foam on the ground inside the foundation is to allow for a shallow footer, I would just go deeper. Why take a chance.
You ran an interior drain. Why? Do you or did yo have a high water issue? A perimeter drain makes sense in many situations, particularly if you don't like gutters, but an interior drain in additon to a perimeter drain seems like a necessity only if you have water coming up from below.
Radon here? Maybe. How does an interior drain line address that issue?
As for following the locals, as I said, I just don't see people building over the winter much. I guess there are several reasons. 1. there are few buildings of developments which typically have GC building year round to keep crews working. 2. For custom homes why build through the winter? 3. The snow! Who wants to frame a floor deck in November and then have to shovel feet of snow off the deck and off the roof a dozen times before the roof is on. That is the case here. That is why I would not build through the winter.
I just don't have much information to go on from the locals as it just is not done much. I did talk to a rare builder last winter building a custom home. He was running a heater in the crawlspace. When I asked if that was to keep the foundation from heaving he said he did not give that any thought. He said he ran it to keep his compressor (in the crawl) from freezing. No real information there.
Where did you build and when?
What is old when considering a DIY build?
As for job, I am self employed and very flexible. I got that covered.
You ran an interior drain. Why?
I built into a hill on the way to a flood plain next to a river. All water coming down the hill that didn't get swaled away could perhaps end up in here. Further as mentioned above-until it was closed in, the foundation could act as a swimming pool wall. In addition, I ran into some shale and if found in this area-probable radon issue. So-kill two birds with one stone. We live in the "basement". Clay soil surrounds and very little if any perc.
How does an interior drain line address that issue?
See above. The drain as it's set up is passive-exits the house downhill side and turns up. Could be made active, but a test after construction proved good on the radon scale.
Where did you build and when?
Why just outside the Glass City of course-Toledo, Ohio. A year and a half b/4 the winter of '89.
What is old when considering a DIY build?
Well, 39 isn't too old, that's when I started this house.
62? My gawd, I hope to tell you.......................
admittedly, 40 yrs of this might just prematurely age a guy.
You made me grab the calculator
I was 43 or 44 when I started building mine here.
You're building on frost susceptible soils so I think you've got two choices. One, you can choose to excavate the clayey sort of muck down to frost depth (plus a bit) and backfill with non-frost susceptible soil. Then build whatever you want... it won't move. At least, frost won't make it move. An earthquake might. Or, you can over excavate by just a few inches, backfill with gravel to keep the bottom of the footer dry. Insulate the foundation with xps foam. Better yet, use ICF's for your foundation. I'd further insulate by extending xps horizontally OUTWARDS from the footer for 24". The foam belongs on the outside not the inside. You want to extend the thaw bulb to totally encompass the foundation and its supporting soil. Build the deck and insulate it with more xps. You can reuse this insulation later on the roof or on/in the walls. Get clever. Install a heat source and keep the foundation above freezing.
Either method will cost you extra money, sorry about that. But, you will rest easy all winter knowing that your expensive foundation is safe.
At the very least it is good to know that I am wise to be concerned. I will have to continue to think about all of this.
Thanks