Medicine Hat has the oldest housing stock of any major city in Alberta, which means it also has the widest range of wall assemblies - and the widest range of right answers.
Know which era you are in before touching a wall
Pre-war and early post-war walls were built without a vapour barrier, often with minimal or no cavity insulation, and many have survived precisely because they can dry freely in both directions. Sealing one up without understanding it is the one genuine risk in this city's older streets. The damage is slow, hidden inside the assembly, and expensive.
1960s-70s walls typically have batt in the cavity and an inconsistent or partial barrier. These are the most common retrofit candidates and usually the most straightforward.
1980s onward generally have a poly vapour barrier as standard. Here the question flips: adding a second vapour-resistant layer inside the cavity can leave the wall unable to dry in either direction.
Three eras, three different correct decisions. The most useful thing you can tell an installer is roughly when the house was built.
The dry-climate advantage
Medicine Hat is one of the driest places in the country, and that genuinely helps. Lower ambient humidity means less moisture available to be driven into wall assemblies, so the consequences of an imperfect vapour strategy are less severe here than on the coast or in a humid climate.
Less severe is not none. It reduces the risk; it does not remove the need to understand the assembly.
Still not the first job
Even with old walls, the attic and rim joist come first. They are open, inspectable, cheaper, and they address the stack effect that drives air through the whole building. In a city where the cheap-gas era left the easy wins untaken, there is usually a lot of value available before anyone opens a wall.
The moments worth acting on
A renovation or re-side, while the cavity is open and visible. Cheapest by a wide margin, and the only approach where coverage can be confirmed rather than assumed.
A specific problem wall - a room that stays cold after the attic and basement are sorted, usually an exposed corner or a wall over an unheated space.
Injecting a closed wall
Possible, and a genuinely different job from spraying an open cavity: different material behaviour, no visual confirmation, no way to inspect afterwards. It suits some houses and not others - injecting spray foam into existing walls covers the trade-offs.
What we do
We are a referral service. We do not install. We connect you with vetted installers - certification, insurance and WCB standing checked.
No price without a site visit, and in a pre-war house we would rather look before recommending anything.
Get a quote, and tell us roughly when the house was built.
See also wall insulation province-wide and when not to use spray foam.