Stand in your garage with the door closed and the lights off on a sunny afternoon. If you can see daylight along the bottom or up the sides, cold air, rain, blowing snow, leaves and mice can get in the same way.
In a lot of GTA homes that matters more than people expect. If there's a bedroom or family room over the garage, if you walk through an attached garage every day, or if the garage doubles as a gym or workshop, those gaps show up as cold floors and a room upstairs that never warms up.
Here's what the different seals do, how they fail and what to fix before the first freeze.
The three seals on most garage doors
The bottom seal. A rubber or vinyl strip that slides into a metal channel (the retainer) along the bottom of the door. It squashes against the floor when the door closes, and it's usually the first seal to wear out.
The side and top seals. Flexible vinyl flaps attached to the trim around the opening. They press against the face of the door when it's closed.
The threshold seal. An optional rubber strip glued to the garage floor. Useful when the floor is uneven or water runs toward the door.
Insulated sectional doors also have tight-fitting joints between the panels, which help keep wind out.
Signs it's time to replace them
- Daylight along the bottom or sides
- Water, slush or leaves blowing in under the door
- A bottom seal that's cracked, flattened, torn or missing in sections
- Side seals that are brittle, curled or pulling away from the trim
- Mouse droppings near the door in the fall
- A door that freezes to the floor in winter
The GTA conditions that wear seals out
Freeze-thaw and uneven floors. Concrete driveways and garage floors move with frost. After a few winters you can end up with a gap on one side and a tight spot on the other. A taller bottom seal or a threshold can close a gap that a standard seal can't.
Road salt. Salty slush drips off cars and sits against the bottom of the door. It's hard on rubber, and it corrodes aluminum retainers. Sometimes the seal itself is fine but the retainer is too corroded to hold it.
Doors freezing to the floor. Meltwater runs under the door and freezes overnight, and then the opener tears the seal when it lifts. Clear slush away from the door before a cold night. If the door is frozen down, free it gently instead of letting the opener force it.
Mice in the fall. Once the nights get cold, mice look for a warm way in, and a worn bottom seal is one of the easiest. A tight seal, especially at the corners, makes a big difference.
Replacing the bottom seal: what's involved
Bottom seals come in different shapes, like T-type, bulb and J-type, and they aren't interchangeable. The new seal has to match the retainer on your door. On older doors it's often worth replacing the retainer too.
After a new seal goes on, the opener's close limit should be checked. A thicker seal can make the opener think it hit something and reverse. The safety reverse should be tested afterward as well.
Side and top seals are usually replaced as one job, with the trim adjusted so the flaps press evenly against the door all the way around.
Seals vs. a new insulated door
New seals help a lot, but they can't make a thin, uninsulated steel door warm. If the room above the garage is still cold after the seals are done, the door itself may be the weak spot. That's where an insulated garage door comes in. We install them across the GTA, from Rosedale and Forest Hill to Oakville and Vaughan.
When to do it
In the fall, before the first hard freeze. Rubber and vinyl are more flexible and easier to fit when it isn't bitterly cold, and you get the benefit all winter.
Get it done
See our garage door weather seal replacement page, or garage door maintenance if you'd like the whole door checked at the same visit. We work across the GTA, including Toronto, North York, Oakville, Vaughan and Markham.
Seeing daylight under your garage door? Call or text Pro GTA Garage at (365) 360-4168, Monday to Friday, 9 AM to 8 PM. Send a photo of the bottom corners of the door and the side trim, and we'll tell you what you need.