Sealing the sides and top of a garage door

Stand inside a closed garage on a bright day and look up the side jambs. On most houses there is a visible line of light down at least one of them, and often across the top. Added up, that is frequently more open area than the bottom of the door, and unlike the bottom it costs about twenty dollars to fix.

Work out the length you need

1. 1Measure the height of one jamb from the floor to the header.
2. 2Double it — you have two sides.
3. 3Add the width of the opening for the header run.
4. 4Add a foot for cutting and corners.
5. 5A typical 7 ft high, 16 ft wide double door works out at about 31 ft. A single 7 x 9 ft door is about 24 ft.

Fitting: the flange pressure is the whole job

1. 1Close the door. Everything is fitted against the closed door, not the open one.
2. 2Hold the trim seal against the jamb so the flexible flange just touches the door face — enough to make contact along its length, not enough to bow.
3. 3Nail the top first with a galvanized nail, then work down, checking contact every couple of feet.
4. 4Do the header last, overlapping the tops of the two side pieces so water runs outward.
5. 5Open and close the door twice. If it binds or the flange folds under, back the seal off a quarter inch and re-nail.

Common mistakes

• Fitting against an open door. The seal ends up nowhere near the door face when it is shut.
• Too much flange pressure. The door binds, the opener strains, and the flange creases permanently within a month.
• Butting the header piece between the sides rather than overlapping over them, so water runs into the joint instead of over it.
• Using vinyl in a severe climate. It stiffens and can crack at the nail line. The rubber version costs a little more.
• Ignoring the jamb itself. If the wooden jamb is rotten, no seal nailed to it will hold. Fix the wood first.

While you are in there

The garage is usually a house's biggest uncontrolled space, and the door is only part of it. Two other checks worth five minutes each: the person door out to the yard, which takes an ordinary door sweep, and the door from the garage into the house, which is often the leakiest interior door in the building — that one has its own page at drafty door to the garage.

Quick picks

Ranked for fit, not for hype. Tap a row to jump to the full write-up, or go straight to the listing.

#	Product	Best for	Gap range	Price
1	M-D Garage Door Top and Sides Seal, 30 ft x 1-1/2 inThirty feet of vinyl trim seal — enough for the top and both sides of a double door in one purchase.	Doing the whole opening	Published 1-1/2 in flexible vinyl flange; overlaps the door face to close the jamb gap	$22.25 · CHECK ON AMAZON
2	Elvone Garage Door Top and Side Seal with Nails, 40 ft, WhiteForty feet with the nails actually in the box — enough to do a double opening's header and both jambs without a second order or a trip for fixings.	Longest run, nails included	Not published as a working gap range; published as a 40 ft roll	$29.99 · CHECK ON AMAZON
3	M-D Building Foam Top and Sides Door Seal for Kerf/Channel, 40 ftThe seal for the other kind of jamb: where the stop has a machined slot rather than a flat face, this foam seal pushes into the kerf instead of being nailed on top of it.	A jamb with a kerf slot instead of flat trim	Not published as a working gap range; published as a 40 ft roll	$17.99 · CHECK ON AMAZON

#ad · how we are funded · price as of October 17, 2026

1

Doing the whole opening

M-D Garage Door Top and Sides Seal, 30 ft x 1-1/2 in

Published gap range

Published 1-1/2 in flexible vinyl flange; overlaps the door face to close the jamb gap

$22.25 · CHECK ON AMAZON

#ad · how we are funded · price as of October 17, 2026

Thirty feet of vinyl trim seal — enough for the top and both sides of a double door in one purchase.

Where the number comes fromM-D publishes the length (30 ft) and the width (1-1/2 in) and states nails are not included. A trim seal does not have a gap range: you nail it so the flange presses against the closed door, which is why install position matters more than the section here.

Published length

30 ft

Published width

1-1/2 in

Material

Flexible vinyl

Fixings

Nails NOT included

Cut

To length

Mounting

Nailed to the jamb (nails not included)

What it does well

• +One roll does the top and both sides of a double door
• +Vinyl flange conforms to a jamb that is not perfectly straight
• +Cut-to-length install with a utility knife

Where it fails

• -Nails are not in the box — buy galvanized ones at the same time
• -Vinyl stiffens in deep cold and can crack if you slam the door
• -Get the flange pressure wrong and the door will not close

Who this is forA garage where you can see daylight down the sides as well as under the door.

• Source: Amazon listing — published 30 ft x 1-1/2 in vinyl, nails not included

2

Longest run, nails included

Elvone Garage Door Top and Side Seal with Nails, 40 ft, White

Published gap range

Not published as a working gap range; published as a 40 ft roll

$29.99 · CHECK ON AMAZON

#ad · how we are funded · price as of October 17, 2026

Forty feet with the nails actually in the box — enough to do a double opening's header and both jambs without a second order or a trip for fixings.

Where the number comes fromNo maker in this category publishes a working gap range, and this one is no exception. What is published is the length: 40 ft, which covers a double opening (roughly 30 ft) with real margin. Judge the flap against your own door-to-jamb gap by eye before committing the roll.

Published length

40 ft

Fixings

Nails included

Use

Top and sides

Finish

White

Published gap range

None

Mounting

Nailed to the stop trim around the opening (nails included)

What it does well

• +40 ft does a double opening with margin, which is where the shorter rolls run out
• +Nails in the box, so the job does not stall for fixings
• +White matches the painted stop trim most garage openings actually have

Where it fails

• -No published working gap range, so the flap depth has to be eyeballed against your gap
• -No named manufacturer data sheet behind the specification
• -White shows the dirt line along a garage opening within a season

Who this is forA double garage door whose perimeter seal is being replaced all round.

• Source: Amazon listing — published 40 ft garage door top and side seal, nails included, white

3

A jamb with a kerf slot instead of flat trim

M-D Building Foam Top and Sides Door Seal for Kerf/Channel, 40 ft

Published gap range

Not published as a working gap range; published as a 40 ft roll

$17.99 · CHECK ON AMAZON

#ad · how we are funded · price as of October 17, 2026

The seal for the other kind of jamb: where the stop has a machined slot rather than a flat face, this foam seal pushes into the kerf instead of being nailed on top of it.

Where the number comes fromBefore ordering, look at the stop your old seal came off. A nailed trim seal sits on a flat wooden stop. A kerf seal pushes into a narrow machined groove in the jamb — common on steel and pre-hung frames. They are not interchangeable, and buying the wrong one is the usual reason a perimeter seal will not stay put.

Published length

40 ft

Fitting

Kerf / channel, not nailed

Material

Foam

Finish

White

Published gap range

None

Mounting

Pushed into the kerf slot in the jamb

What it does well

• +Fits the kerfed jambs that a nailed trim seal cannot serve at all
• +40 ft covers a double opening in one roll
• +No nails, so nothing splits the stop trim

Where it fails

• -**Only works on a jamb with a kerf slot.** On a flat wooden stop it has nothing to grip
• -Foam is less durable outdoors than a vinyl or rubber trim flange
• -No published working gap range, which is true across this whole category

Who this is forA garage or service door whose jamb has a machined slot rather than flat trim.

• Source: Amazon listing — published M-D foam top and sides seal for kerf/channel, 40 ft