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Every garage door leaves gaps by design. The curtain or panels have to clear the floor and the frame to move, and it is the seals, not the door itself, that shut those gaps against rain, wind, dust, leaves and the occasional gecko. Because seals are soft, they are the first part of a door to wear out, and because they are cheap they are usually the last part an owner thinks about. This guide sorts the seal types by where they sit, so you can work out which one is letting the weather in.
The four kinds of garage door seal
The garage door bottom seal
The bottom seal runs the full width of the door along its lowest edge. On a sectional door it is a rubber strip that slides into a retainer on the bottom panel, and its profile matters: some retainers take a strip with two T-shaped ends, others a bead or a bulb shape, and a strip cut for the wrong retainer will not stay in. On a tilt door the bottom seal is often a flat rubber or vinyl blade screwed to the inside face of the panel so it drags lightly over the floor as the door closes.
The job of the bottom seal is to compress against the floor when the door is fully down. If the floor slopes, a fatter bulb seal can bridge a small difference; a large difference is a floor or door-level problem, covered further down.
Side and top seals
Sectional and tilt doors also seal around their perimeter. A flexible flap, usually rubber on a rigid backing, is fixed to the jambs on each side and to the head above the opening so it lightly touches the outside face of the closed door. These are the seals that stop driving rain and dust blowing in around the edges, and they are what people see daylight past when they fail. They are also where a door that has shifted in its tracks first shows up, because one side seals and the other does not.
Roller door seals: brush strips and rubber
A roller door curtain runs inside vertical guides, so a flap seal on the jamb would foul the curtain. Instead, a roller door seal is usually a brush strip fixed inside or alongside the guide, with dense bristles that sit against the curtain as it rolls past. Brush strips let the curtain move freely while still stopping dust and insects. Along the bottom rail, a roller door uses a rubber strip, often a U-shape clipped over the rail, to seal against the floor. Both are stocked as standard roller door repairs parts.
Threshold seals
A threshold seal is different from the others because it fixes to the floor, not the door. It is a raised rubber strip glued across the opening so the bottom seal lands on it rather than on the slab. Thresholds suit garages where water pools at the door or the driveway falls toward the garage, and they work best paired with a bottom seal in good condition rather than as a substitute for one.
How to tell a garage door seal has failed
Signs, with the likely seal
- A line of daylight under the closed door, or a puddle inside after rain: the bottom seal has hardened, split or shrunk, or the door is no longer level.
- Daylight or a draught down one or both sides: a perimeter flap seal has torn, curled or pulled away from the jamb.
- Fine dust and leaf litter inside a roller door garage: brush strips have worn thin or fallen out of the guide, or the bottom rubber has split.
- Rubber that is cracked, chalky or crumbles when you press it: sun and heat have finished it, whether or not it is leaking yet.
- Ants, cockroaches or geckos finding their way in at floor level: the bottom seal no longer compresses evenly.
- The bottom seal is intact but flattened on one end: the door sits lower on that side, and the seal is a symptom, not the cause.
Perth sun is hard on rubber
West- and north-facing doors take direct afternoon sun on the bottom seal, and rubber that bakes every summer hardens sooner than rubber in shade. If the door faces the sun, check the seals each time you check anything else on the door.
Are garage door seals universal?
No, and this catches out plenty of hardware-store shoppers. Bottom seals differ by the profile of the retainer they slide into, by width and by the door type. Perimeter seals differ by how they mount. Brush strips come in different bristle depths and backing widths to suit the guide. The reliable way to buy the right seal is to cut a short piece off the old one and match it, or measure the retainer slot and the width of the bottom rail. A technician carries the common profiles and matches them on the spot.
Garage door weather seal replacement: what is involved
- Identify every seal that has failed, not just the obvious one. A new bottom seal fitted under a torn side flap moves the leak sideways.
- Bottom seal on a sectional door: the old strip is slid out of the retainer, the channel is cleaned of grit, and the new strip is fed in and cut to length with a little spare so it can be trimmed once it has settled.
- Bottom seal on a roller or tilt door: the old rubber is unclipped or unscrewed from the rail and the new strip fitted the same way, with the ends closed so water cannot track inside the profile.
- Perimeter seals: the old flaps are removed, the jambs and head checked for damage, and new lengths fixed so they just touch the door face without dragging.
- Brush strips on a roller door: worn strips are drawn out of their carrier and new ones inserted, with the curtain run to confirm the bristles brush rather than bind.
- Finally the door is closed and checked for daylight from inside, and for even contact along the floor.
Leave the bottom brackets alone
On a sectional door the bottom panel also carries the bottom brackets, which anchor the lift cables. Those cables are under spring tension even when the door is closed. Replacing a bottom seal never requires loosening a bracket, and if a seal retainer is bolted through one, that is a job for a technician.
Gaps a new seal will not fix
A seal can only close a gap that is roughly even. If the gap under the door is a finger on one side and nothing on the other, the door is out of level in its tracks, the floor has moved, or a cable has stretched, and a fatter seal only hides it for a season. A bottom rail that has been backed into by a car will not hold any seal flat. And a roller door that has crept sideways in its guides will chew through new brush strips on one side while leaving a gap on the other. In each case the door needs attention first; the seal comes second.
When to call a technician
Book a visit when more than one seal has gone, when you cannot match the profile, when the gap is uneven, or when you simply want it done with the rest of the door checked at the same time. Elite replaces the rubber floor seal and brush seals as a set for $280–$480 incl. GST, and checks the door's level and travel while there. If the door is due anyway, a garage door service from $140 plus parts, incl. GST, includes the seals in its inspection, and general garage door repairs cover a bent bottom rail or a door that has dropped on one side.