How do I replace the bottom seal on a garage door?

Replacing a garage door bottom seal is a job a careful homeowner can do, as long as they leave the springs, cables and bottom corner brackets alone. The key is matching the seal to the retainer on your door, then sliding the old one out and the new one in.

Start with the retainer

Look at the bottom edge of the door. The rubber seal sits in a channel, called the retainer, fixed to the bottom section. Garage doors are manufactured with varying types of weather seal retainer designs, so the seal you buy has to fit yours.^[1] Clopay's U-shaped seal fits U-shaped retainers and its bulb seal fits bulb-shaped retainers.^[1]

Take a photo of the end of the old seal, or cut off a short piece to carry to the supplier. Measure the width of the door and buy a seal at least as long.

If your floor is not level, note that for non level floor surfaces, special weather seal may be available.^[1] Ask about it before you buy a standard strip.

Before you start

Disengage the opener. Clopay's instructions are plain: if your door is connected to an automatic opener, be sure to disengage the opener before beginning work.^[1] Then raise the door to the open position and clamp both tracks with C-clamps or locking pliers directly below the door and tighten, so it cannot drop.^[1]

A door that will not stay where you leave it is a sign of a balance problem. CPSC warns that if doors are not "balanced," or if they bind or stick, they should be serviced by a professional.^[4] Do not carry on with the seal.

Swap the seal

Slide the old seal out of the retainer, working from one end. On some doors you must first remove screws holding the weather seal to the retainer, as the Clopay instructions put it: it may be necessary to remove screws holding weather seal to retainer.^[1]

For a U-shaped retainer, insert the new seal's T-shaped edges into the slots and slide the seal across the full width of the door.^[1]

For a bulb-shaped retainer, make a bulb shape from the flat strip of weather seal by curling the ends together, then feed the T at the top of the bulb into the slot.^[1] The weather seal will slide through the retainer slot easier if soapy water is applied.^[1]

Finish by trimming. Cut off excess weather seal flush leaving two extra inches from the edge of door.^[1] Tuck extra weather seal into itself to allow for future shrinkage.^[1] Put back any screws you took out.

Test before you walk away

Take off the clamps and reconnect the opener. Then run the door through a full cycle and watch the new seal: it should sit evenly along the floor without folding under or dragging.

Finally, check the reverse function. CPSC's test uses a 2x4 on the floor in the door's path, and if the door does not properly reverse when striking the 2x4 then the garage door opener should be disengaged until it is adjusted, repaired or replaced.^[4] Repeat the test after any seal change.

What the seal does

A bottom seal blocks drafts, rain and leaves at the gap between the door and the slab. The Department of Energy lists weather stripping materials for doors that include aluminum or stainless steel door sweeps, metal gaskets, bulb or fin seals.^[3]

Stop and call a pro if

• The door is heavy, unbalanced or will not stay up. Springs do the lifting. Clopay's manual says that if your old door uses torsion springs, do not attempt to remove the door or the springs yourself.^[2]
• The retainer is bent, rusted through or loose. That is a bottom section repair, not a seal swap.
• The seal is stuck behind a bottom corner bracket. The brackets at the bottom corners of your garage door are under great tension.^[2] Do not loosen them.
• The door binds or sticks. CPSC says it should be serviced by a professional.^[4]
• The door does not reverse after the swap. Leave the opener disengaged and call a door technician.^[4]

Getting help in Virginia

If the seal is only part of the problem, see how to quiet a garage door, what the job costs and how to replace a broken hinge. Browse more garage door answers, or see garage door pros on Loclis.

When you would rather hand it over, describe the job and local garage door pros will quote it.