If a door is sitting crooked, the weather seal is a symptom, not the cause. The seal cannot pull a door out of square. What happens is the door racks in the opening, one side sits higher than the other, and the bottom seal no longer meets the slab evenly. You get a gap at one end, water and wind come in, and the seal wears unevenly where it is still making contact.
Fixing the seal on a crooked door is a waste of a seal. It will fail the same way again within months because the door is still travelling out of square.
What puts a door out of square
- A broken or slipped lifting cable. One side drops and the door racks. The most common cause by far.
- A drum that has slipped on the shaft. A set screw backs off and that side stops winding properly.
- Bent or spread track. Usually impact damage. The door binds through that section and pulls over.
- Failed hinges or a cracked section. The door folds unevenly at the damaged point.
- A broken spring on a two-spring system. The door goes out of balance and the weak side lags.
- An out-of-square opening. On older buildings the slab or the jambs have moved. The door is fine; the hole is not.
Why the gap matters beyond the draught
An uneven bottom seal lets water track along the slab into the building. On a loading dock or a parkade that becomes a slip hazard and, in winter, an ice problem. It also lets vermin in, which matters a great deal in food handling and storage.
The bigger issue is that a crooked door is mechanically unsound. Cables under uneven tension can fail. A racked door can jump the track entirely.
The right order to fix it
- Find out why the door is out of square and correct that. Cables, drums, track, hinges, sections, springs.
- Re-level the door on the shaft and set the balance.
- Then fit the bottom seal, and check the opening for square while doing it. If the slab is uneven, the seal has to be chosen to suit.
Seal types worth knowing
- Bulb seal. The common T-slot or P-slot rubber on the bottom of a sectional. Handles a reasonably flat slab.
- Brush seal. Used where there is grit, or on rolling steel.
- Threshold seal. Fitted to the slab rather than the door. Useful where the floor has worn or dished.
On a slab that has settled, a standard bulb seal will never close the gap. That is a case for a threshold or a custom profile.
If your door is crooked and the seal has stopped sealing, deal with the door first. Call (604) 206-5727.
