Keeping Mice and Bugs Out: Sealing the Garage Door

Every fall around Greene County, mice move indoors, and the garage is the front door. They do not chew through the garage door. They walk in under it, at the corners, or along the sides, through gaps that are there all year and only get noticed when something starts living in the tool bags. Here is where those gaps are and how to close them.

The four gaps

Under the door. The bottom seal is a rubber or vinyl strip in a retainer along the bottom of the door. When it hardens, cracks, or flattens, daylight shows underneath and a mouse walks straight through. An uneven or cracked floor makes it worse, because the seal cannot follow the dips.

The bottom corners. Even with a good bottom seal, the corners where the bottom seal meets the side weatherstripping are a common entry. The seal ends short, or the side stripping does not reach the floor, and a small triangular gap is left at each corner. This is the gap people miss.

Along the sides and top. Perimeter weatherstripping, the vinyl strip nailed to the jambs and header, seals the door against the frame. When it has pulled away, shrunk, or was installed with gaps, there is a path along the whole edge of the door.

Between sections. When the door is closed, the joints between panels should meet snugly. Worn or missing section seals leave a horizontal gap at each joint, mainly a problem for insects and air.

Fixing each one

Bottom seal. Replace it. Slide the old one out of the retainer, slide the new one in. Match the retainer profile (T-style, bead-style, or nailed-on) and buy a seal a little longer than the door so it can be trimmed. On an uneven floor, a taller or bulb-type seal follows the dips; for a bad gap, a threshold seal glued to the floor gives the bottom seal something flat to land on. Our post on bottom seals and thresholds covers the choices.

Corners. After a new bottom seal, check the corners with the door closed. If a gap remains, corner seal pads or a short piece of extra weatherstripping close it. A little exterior sealant along the outside of the corner gap is a reasonable stopgap.

Perimeter weatherstripping. Replace it with new vinyl or rubber stripping, installed with the door closed so it presses against the door face without binding. It should run all the way to the floor on each side.

Section seals. Some doors have replaceable seals in the section joints; on others the joint is a tongue-and-groove that seals on its own when the door is adjusted correctly. A door that does not close fully, because the travel limit is set short or the floor is uneven, leaves every joint slightly open.

When a seal is not enough

A seal only works against a door that closes squarely. If the door sits crooked on the floor, one side has a gap no seal can fill. Causes are a cable that has stretched or jumped on one side, worn rollers, or an opener travel limit set too short. Our post on a door closing crooked covers the diagnosis. Get the door closing straight first; then the seals can do their job.

Also look at the rest of the garage. A gap under the door is the most obvious entry but not the only one: the gap around the man door, unsealed penetrations for wiring and plumbing, gaps at the sill plate, and vents without screens are all mouse-sized. Sealing the garage door and leaving those open moves the problem, not solves it.

Snakes, spiders, and everything else

The same gaps admit snakes in warm months and spiders and crickets year-round. Snakes follow mice, so the door seal helps twice. Reflective or brush-style weatherstripping at the sides deters insects better than a simple vinyl flap, and a tight bottom seal keeps the garage darker, which many insects avoid.

Maintenance

Bottom seals and weatherstripping last a few years, less in a sunny exposure. Check them each fall as part of a seasonal walk-around: close the door, turn off the lights, and look for daylight. Anywhere you see light, a mouse sees a door. Our seasonal checklist includes it.

What we do

Greggs Garage Door Services replaces bottom seals, threshold seals, and perimeter weatherstripping as part of a tune-up or as a standalone visit, and we fix the crooked-closing problems that make seals useless. Flat rate, written quote, free diagnostic. See our post on weather seal replacement for what the job involves.

Common questions

Can mice get in around a closed garage door? Yes, through the bottom corners and under a worn seal. A mouse needs a gap roughly the size of a dime.

Will a new bottom seal fix an uneven floor? A taller or bulb seal helps; a threshold seal on the floor fixes it. Sometimes both.

Is a brush seal better than vinyl? For pests and blowing debris, brush seals on the sides work well. For water at the bottom, a rubber bulb seal is better.

How do I know whether it is the door or something else? Turn off the lights and look for daylight around the door. If the door is dark and mice still come in, the gap is elsewhere in the garage.

Call (423) 262-3147 or request a free quote.