Actually on Mars it would (or so it's thought) create a sort of self sealing system. The building's atmosphere will contain humidity, so as air leaks out through the super cold Martian soil that moisture will freeze, sealing the leak.
It's also worth pointing out that the buildings don't have to be perfectly air tight. Small slow leaks are quite acceptable.
It's also worth pointing out that the buildings don't have to be perfectly air tight. Small slow leaks are quite acceptable.