The four seals on a sectional door
A garage door seals in four places. The bottom seal is a rubber or vinyl strip along the bottom section that squashes against the slab. The perimeter seal (stop moulding or jamb seal) runs up both sides and across the top on the outside of the opening and lays a flexible lip against the door face. The top seal on some doors is a separate strip along the top section that meets the header. And on rolling steel and commercial doors, brush seals in the guides and at the hood take the place of rubber. Between them they keep out driving rain, leaves, wind and most of the mice.
Bottom seals
The bottom seal is held in a retainer: either a channel built into the bottom of the door section (most steel doors), an aluminium retainer screwed to the bottom of a wood or older door, or a steel retainer on commercial doors. The retainer decides which seal profile fits, which is why "bottom seal" is not one part. Seen end-on, the common profiles are:
| Profile | Retainer | Common on | Notes |
|---|---|---|---|
| T-type (two T ends) | Single or double channel aluminium or steel retainer | Wood doors, older steel doors, most aftermarket retainers | The T stems slide into slots; widths 1/4" and 5/16" T |
| Bead / round-end | Channel formed into the bottom of a steel section | Most steel residential doors | Round beads of about 1/4" or 3/8"; brand-specific spacing between beads |
| Bulb | Flat flange in a channel, bulb below | Doors over uneven or sloped slabs, commercial | Hollow bulb from 2" to 4" diameter fills bigger gaps |
| Bulb with cord / flat-flange | Screwed flange, no retainer | Commercial, older residential | Screwed straight to the bottom rail |
To identify yours: close the door, go inside, and look at the bottom edge from the end. Pull the end of the seal out of the retainer an inch and look at its cross-section. A T-shaped end means T-type; a round ball end means bead; a flat flange with a tube below means bulb. Then measure the width of the retainer channel opening and the overall width of the seal flat. Bring those numbers and you will get the right part first time. The homeowner maintenance checklist covers the seal check along with the rest of the yearly look-over.
Perimeter stop seal
The perimeter seal is a vinyl or aluminium strip with a flexible flap, nailed or screwed to the outside of the jambs and header so the flap presses against the face of the closed door. Residential widths are 2" and 2 1/2"; some are a vinyl-clad wood stop. It stops wind-driven rain coming in around the edges, which on a west-facing door in White Rock or West Vancouver is most of the water that gets into a garage. When the flap goes hard it stands off the door and you see daylight at the sides; when the nails rust out it flaps in the wind. Replacing it is a hand saw, a mitre at the corners, and a box of galvanised nails or screws.
Top seals and brush seals
Some doors have a lip seal on the top section that meets the header; most rely on the perimeter seal there. Brush seals are nylon bristles in an aluminium holder, used along the guides and hood of rolling steel doors and on commercial sectional doors where a rubber lip would wear through in a season. They do not seal water the way rubber does, but they handle grit and keep working when the door is slightly out of true.
What the climate does to them
- Bottom seals go hard and crack. Vinyl seals stiffen in the cold and sit in water for months. Once the seal is hard it no longer squashes to the slab and a wet strip appears inside the door. Rubber (EPDM) seals stay soft much longer than vinyl here.
- Seals freeze to the slab. The few hard frosts we get each winter freeze the seal to a wet slab. The opener pulls, the seal tears or the bottom section bends. Silicone spray on the seal before a cold snap, and a dry slab, prevent it. Never force the opener; the opener repair calls after a freeze are mostly this.
- Slab gaps. Older garages on fill in Richmond, Delta and Surrey have slabs that have cracked or heaved, so the bottom seal meets the floor on one side and hangs an inch above it on the other. A bulb seal takes up some of that; a threshold seal glued to the slab takes up the rest.
- Rodents. Mice chew the corners of a bottom seal where it meets the perimeter seal. Rubber corner blocks or a brush seal corner fix it.
Which seals you can do yourself
All of them, with one note. The bottom seal slides out of its retainer from one end with the door closed; there is no tension involved and it is a twenty-minute job with soapy water to help the new one slide in. The perimeter seal is a carpentry job. The one thing to watch is the bottom bracket at each end of the bottom section: it holds the lift cable under spring tension, and some aluminium retainers are screwed close to it. Do not remove or loosen the bottom bracket bolts to get a retainer off. If the retainer itself is rusted or bent, or the seal change turns into a bottom section repair, that is where we come in; it is often done as part of a maintenance visit along with the rollers and bearings.
Not sure which part you need?
Send a photo of the part to (778) 873-7282 on WhatsApp or text, or use the contact page. We identify it, bring the right one, and fit it the same visit.
Contact us(778) 873-7282