My issue: The floor is bloody cold in the winter and I'm done with it and need to do something to make my power bills lower and to make the house comfortable in the winter. I live in eastern Canada (climate zone 6).
I have an older home built during the 40s. It's a one story house approximately 625 ft2 which an unconditioned crawl space underneath. The crawlspace does not have a foot and as such, water gets into the space regularly through the year, especially in the spring. The space does drainage and a sump pump to manage the water.
First, I know from doing enough research and previous post searches that the right way to insulate my floor is to insulate the foundation wall with a vapour barrier on the ground and make it an encapsulated space. I am not willing to do this due to water issues which would cost 10x more than I'm able to afford.
I'm looking for some advice. Is there any benefit to sealing and insulating the rim joist if I only intend to insulate the floor underside and not the space? Next, would I be better off to use batts between the joists or rigid foam insulation? Batts seem to need less material for a given R value. Finally, do I need a vapor barrier against the floor before I install the insulation and how is it practical to install between all the joists? Is there an insulation that will also provide the vapour barrier as well?
Would I be better off to eat the cost and have a contractor spray in foam insulation? It is costly but the local government has decent rebates on at the moment. It will still be more than DIY approach.
Unless you fully encapsulate the space, all of your ideas here would create problems.
You'd be trapping moisture, and that's a recipe for mold.
Possibly add a dehumidifier and/or an air exchanger, and then seal if you as best you can
.... I don't know if any of that's viable. How much headroom do you have down there?
4 ft or so. It’s been an open unheated space for 75 years. There’s no signs of rot. But the space can’t be made watertight with major yard work. It’s not worth it for the value of the house.
First, do you have any plumbing down in that space,besides the sump pump? If not, you could insulate the floor cavities, so long as the crawl space is ventilated to allow excess moisture in the space to dissapate. You could insulate the joist bays with foam board, aiming for an R-20 minimum, which will keep the floor quite warm.
If you do have plumbing down there, is it close enough to the joists that you can fur out the joists, and do foam board below that? Again, ventilate the crawl space, but you do not want to run the risk of the plumbing getting cold enough to freeze.
Either way, R20 minimum is what you want to insulate to over an unconditioned space.
There is plumbing down there. Some insulated (if you want to call it that) and some not. There’s really only a main water line into the house and the main drain back to the city sewer.
You could put heat tape on the pipes, insulate them properly, and then just insulate between the floor joists, and ensure the space is ventilated to mitigate the humidity. That should resolve the cold floor, and keep the pipes from freezing.
From what I've heard rats love the insulation, so besides the moisture issues caused by putting in batts, it's another reason why it's not recommended any more.
Funny enough I just dealt with a rat issue some this ago. Thankfully it left on its own accord.
he didnt like how cold it was