Mice Are Getting In Through Your Garage Door — Here Is How to Fix It
If you have an attached garage and you have mice, I can tell you with about 80% confidence where they are getting in. Your garage door.
Not through a crack in the foundation. Not through a hole in the wall. Through the gap at the bottom of the garage door that you have walked past a thousand times without thinking about it.
Why the Garage Door Is the Problem
A standard residential garage door has a rubber seal along the bottom edge. This seal is designed to keep out rain and snow. It is not designed to keep out mice.
Over time — usually 3-5 years — the seal:
- Hardens and cracks from UV exposure and cold
- Warps from contact with ice and salt
- Gets chewed by mice that have already found the gap
- Wears unevenly, creating gaps at the corners
The $20 Fix
A replacement garage door bottom seal costs $15-$25 at any hardware store. It takes 20-30 minutes to install.
What to buy: A T-style or U-style rubber seal that matches your door width. Measure the door width before you go. Bring the old seal if possible for matching.How to install:
1. Open the garage door 2. Remove the old seal by pulling it out of the track (most slide out from one end) 3. Clean the track channel 4. Slide the new seal in from one end 5. Close the door and check for gaps — the seal should compress firmly against the floor with no daylight visible 6. If the floor is uneven, use a threshold seal (a raised rubber strip that screws into the concrete) to create a tighter fit Check the side seals too. The weatherstripping along the sides of the garage door can also deteriorate. Replace if you see gaps or daylight.The Garage-to-House Door
Even with a perfect garage door seal, mice that enter the garage can access your living space through the interior door connecting the garage to the house.
Check this door for:
- Gap at the bottom — install a door sweep if you can see daylight
- Gaps around the frame — caulk or weatherstrip
- The door itself — does it close completely and latch? A door that is slightly ajar is an open invitation
Beyond the Door: Other Garage Entry Points
While you are fixing the door, check these common garage entry points:
- Where the garage meets the house — the junction between the garage wall and the house wall often has gaps, especially in attached garages added after original construction
- Utility penetrations — gas lines, electrical conduits, and water pipes entering through the garage wall
- The garage ceiling — if your garage has a finished ceiling, check for gaps around light fixtures and ceiling penetrations. Mice travel through the space between the garage ceiling and the floor above.
- Foundation vents — if your garage has foundation vents, they should be screened with hardware cloth
The Cost of Not Fixing It
A garage door seal: $20 and 30 minutes.
A mouse infestation from an unsealed garage door:
- Exterminator visit: $200-$400
- Multiple follow-up visits: $100-$200 each
- Damaged stored items: variable
- Chewed car wiring: $500-$4,000
- Contaminated insulation in the garage ceiling: $500-$2,000
- Stress, lost sleep, and time spent dealing with the problem: priceless
Frequently Asked Questions
How often should I replace my garage door seal?
Every 3-5 years, or immediately if you see visible gaps, cracks, or daylight under the closed door. In Montreal, the combination of extreme cold, road salt, and UV exposure degrades seals faster than in milder climates.My garage door seal is fine but I still have mice in the garage. Where else are they getting in?
Check the junction where the garage wall meets the house, utility penetrations (gas line, electrical panel conduit), and any gaps around windows or vents. Also check the top of the garage door — the header seal can deteriorate and create a gap that mice access by climbing the door track.Got a pest problem?
Extermination DMP serves Montreal, the South Shore, Laval & the West Island — 24/7.
Call 438-879-5706