Insights
How to rodent-proof a home before September
Mice move with the first cold nights. The work that matters is at grade, the garage, and every pipe that punches the envelope.
Framework Pest · PMP® · M.Sc. Architecture · 2026-08-04 · 7 min
Calgary mice do not wait for snow. Pressure rises in late August and September as nights cool and food sources shift. The buildings they prefer are not ‘dirty.’ They are open at the sill, the garage weatherseal, the AC line set, and the deck ledger that was never flashed or meshed.
A useful home program, in order: (1) Walk the perimeter at dusk with a flashlight at grade — look for 6 mm gaps at utility penetrations, weeps, and where stucco or hardie meets the foundation. (2) Fit door sweeps that actually kiss the threshold, including the garage man-door. (3) Screen dryer, bath, and HRV exhausts with metal, not plastic. (4) Pack and seal pipe sleeves with copper mesh and a sealant that moves. (5) Lift the deck or step where it meets the house; that cavity is a highway.
Traps are for the population already inside. They are not rodent-proofing. If you have had mice two winters running, the envelope is the job. Framework’s residential assessments produce a photo-ranked list so a homeowner or a contractor can close the right gaps once.
Do this before the first stretch of nights below 5 °C. After that you are managing a population and an open building at the same time.
