What is the best way to insulate a crawl space?
Hi, I have a small cottage in sothern ontario (Canada) than I am going to rent out for the winter, it was never used in the winter and we have installed a furnace in the small basement, the rest of the cottage is crawl space with dirt(sand) floor, there is a couple heat ducts set up to blow heat down there. I will install insulation over the water supply lines with heat tape, nothing over the drains or pee traps. The walls in the crawl space has been insulated with 1" rigid insulation the cottage itself has been well sealed, the floor joists on one 1/2 of the cottage has R12 between the Joists, the other 1/2 looks like it has ceiling tiles between the joists for a bit of insulation. The question is, should I remove the insulation between the joists and install rigid insulation over the dirt floor? Or insulate between all the Joists? Or would just vapour barier above the ground sufice? Will the 2 heat ducts be enough to keep everything from freezing down below for the winter, also should anything be done with the drain lines?
Also as a second thought the area that the floor is insulated with R12 is where there is no water lines would it make sense to curtain that area off and just focus on keeping the side with the water lines warmer.... the cottage is only 670 sq feet.... so not large
The best way to insulate a crawl space depends on a few things, mostly whether or not you plan to heat it. You can either treat it as a separate space (keep it cooler) or treat the home and crawl space as one single space with the same thermal conditions. There are a lot of things you bring up here, most of your questions will probably be answered in this page –
Insulating crawlspaces as part of home renovation
The insulation between the joists - assuming it is not moldy and is in good condition – is good to have if you keep the crawl space at a lower temperature. If you keep it at the same temperature as the rest of the house then it won’t do much but it isn’t a problem so you can probably just leave it there, again that is assuming it isn’t moldy.
Your situation is a bit complicated given these two separate spaces insulated in different ways, but the main thing is to make sure it is insulated somewhere at least, be it between the joists or the floor. You can leave a section cold if there are no pipes in it, but your tenants will likely notice that on the feet. So if you have some sort if work to do down there I think it may be easiest, and most comfortable for occupants, to treat it all as one space, insulate the floor and keep it warm. Most importantly for durability, healthy air quality and energy efficiency is to cover the dirt with a membrane to keep moisture in the ground.