Medicine Hat is one of the driest, sunniest places in Canada. People assume that means crawl spaces here stay dry.
The air does. The ground does not.
Dry climate, damp ground
A crawl space takes its moisture from two sources, and they behave differently.
The first is the air you let in. In a humid climate that is the dominant problem. Here it is much less of one - the outside air is genuinely dry for most of the year, which is a real advantage over a coastal or lakeside location.
The second is the soil directly underneath, and that does not care what the weather is doing. Ground moisture migrates upward continuously, all year, regardless of how dry the air above it is. In a crawl space with bare earth and no barrier, that moisture has nowhere to go but into the space and then into the floor system above it.
So the common Medicine Hat mistake is skipping the ground barrier because the climate feels dry. The climate is dry. The dirt is not.
The swing is the other half
Southeast Alberta runs hot summers and cold winters with a large spread between them, and a crawl space sits at the bottom of that swing with very little thermal buffering.
In winter a vented crawl space tracks the outside temperature, which makes the floor above it cold and puts any plumbing down there at risk. In summer, warm outside air entering a cooler crawl space can condense on the surfaces down there - the one time of year when ventilating actively adds moisture rather than removing it.
Neither problem is solved by insulating between the floor joists, which is what most older houses here have. That keeps the house marginally warmer while leaving the crawl space itself outside the building.
What actually works
In order, and the order matters:
- A continuous ground barrier across the soil, sealed at the seams and up the edges. This comes first. Sealing a crawl space without it produces a closed humid box.
- Seal the vents. They are why the space tracks the outside.
- Insulate the perimeter walls, not the joists. This brings the whole space inside the building, protects the plumbing, and keeps the floor above warm.
- Seal the rim joist while access is open - it is the leakiest part of the assembly and you are already down there.
Before anyone sprays
Look for standing water or a history of it. Foam is not waterproofing and must never be used to cover a drainage problem.
What we do
We are a referral service. We do not install. We connect you with vetted installers - certification, insurance and WCB standing checked - and they quote you directly.
No price without a site visit. Access drives cost in a crawl space as much as area does. Get a quote, and say whether the floor down there is bare earth.
See also crawl space insulation province-wide and Medicine Hat basements.