Every garage door has four seals, and the one along the bottom does most of the work: it stops water, leaves, cold air, and the occasional lizard from coming in under the door. It is also the seal most likely to be hardened, split, or missing on any door older than a decade. This guide identifies the seal you have, gives the sizes and materials that fit, covers the three seals people forget, and walks through replacement, from techs who change dozens a month across metro Atlanta.
01The quick answer
If you just need to buy the right part:
- Most steel doors built since the 1990s use a T-end bottom seal that slides into an aluminum retainer. The T stem is 1/4 inch on most brands and 5/16 inch on some, and the two are not interchangeable.
- Standard width is 3 to 4 inches measured flat. Go to 5 or 6 inches when the floor slopes or the gap is over 1/2 inch.
- Length is the door width plus a couple of inches to trim: 9 or 10 feet for a single door, 16 or 18 feet for a double.
- Wood doors and many older doors use a nail-on flap seal instead of a retainer.
- Vinyl is the common material and lasts about 5 to 10 years here. Rubber costs more and stays flexible longer.
The rest of this guide covers how to tell the types apart, what the retainer has to do with it, and the perimeter and threshold seals that finish the job.
02The four seals on every garage door
People say "weather stripping" and mean the bottom seal, but a sectional door seals in four places, and a draft or a puddle can come from any of them:
- Bottom seal. The flexible strip along the bottom edge of the lowest section. It compresses against the floor when the door closes and takes up the small unevenness every slab has.
- Perimeter seal, also called stop molding or jamb seal. The vinyl or rubber flap fixed to the door frame on both sides and across the top. The door face closes against it, sealing the gap between the door and the framing.
- Section joints. Where the horizontal sections meet. Modern doors use a shiplap or tongue-and-groove joint that seals itself when the door is closed; some brands add a thin rubber joint seal, and older flat-joint doors seal poorly here.
- Threshold seal. Optional. A raised rubber strip glued to the floor under the closed door. It gives the bottom seal a lip to close against and blocks water running in from the driveway.
What each part of the door around those seals is called, sections, tracks, retainers, and the rest, is mapped in our garage door anatomy guide.
03Bottom seal types and retainers
The seal is only half the story. Most doors carry an aluminum retainer along the bottom edge, and the seal's end profile has to match the retainer's channel. Turn the seal end toward you and the shape tells you what you have:
| Seal type | End profile | Fits | Typically found on |
|---|---|---|---|
| T-end (T-style) | A T on each end, 1/4 in or 5/16 in stem | Double-channel aluminum retainer | Most steel doors from the 1990s on; the industry default |
| Bead-end | A round bead on each end, about 3/8 in | Double-channel retainer with round grooves | Some steel and older doors; regional |
| Bulb | One large round tube, single flat tail | Single-channel retainer | Older steel doors, some wood doors with a metal retainer |
| J-type | Two hooked ends | Single-channel retainer | Older steel doors of a few brands |
| Nail-on / staple-on | Flat flap, no end profile | Nailed to the bottom of the door | Wood doors, many pre-1990 doors |
Two practical notes. First, the T size matters: a 5/16 seal will not slide into a 1/4 retainer and a 1/4 seal will drop out of a 5/16 one. Measure the stem width on the old seal or the channel opening on the retainer. Second, if the retainer itself is bent, corroded, or missing sections, replace the retainer along with the seal. A new seal in a crushed retainer seals about as well as the old one did. Retainers are sold to match door widths and screw to the bottom section, and they are part of the hardware we carry on our track and hardware calls.
04Bottom seal sizes
Three numbers describe a bottom seal: the T or bead size, the flat width, and the length.
| Measurement | Common sizes | How to pick |
|---|---|---|
| T stem | 1/4 in, 5/16 in | Match the retainer. Measure the old seal's stem or the channel opening. |
| Flat width | 3 in, 3-1/2 in, 4 in, 5 in, 6 in | 3 to 4 in for an even floor with a gap under 1/2 in. 5 to 6 in for sloped or uneven floors and gaps up to about 1-1/2 in. |
| Length | 9 ft, 10 ft, 16 ft, 18 ft, 20 ft rolls | Door width plus 2 in, then trim flush. Standard door widths are in our size guide. |
| Bulb diameter | 1/2 in, 3/4 in, 1 in | Bulb seals only. Match the old bulb; larger bulbs cover larger gaps. |
| Nail-on flap | 2-3/4 in to 3-3/8 in wide | Wood doors. Wider flap for a bigger gap; the flap folds under the door. |
Wider is not automatically better. A 6 inch seal on a level floor bunches up and can trigger the opener's close-force reversal, so the door goes back up an inch off the floor. If a new seal causes that, the fix is a narrower seal or a force adjustment, not a heavier door. Our won't open or close guide covers the reversal symptoms in detail.
05Vinyl, rubber, or TPE
Bottom seals come in three materials, and the difference shows up in year six, not on day one:
- Vinyl (PVC). The standard. Cheapest, widely stocked, fine for most doors. It hardens with sun and heat and eventually cracks at the fold. Expect 5 to 10 years in metro Atlanta, toward the low end on a door that faces west.
- Rubber (EPDM). Costs more, stays flexible in cold weather, resists UV better, and holds its shape longer. Our default recommendation for doors that see full afternoon sun or sit on an uneven floor, where the seal is flexing hard every cycle.
- TPE (thermoplastic elastomer). The newer middle ground: rubber-like flexibility, vinyl-like price, and it is what several manufacturers now ship on new doors.
Whatever the material, look for a seal with a hollow, U or bulb shaped middle rather than a flat strip. The hollow is what lets it compress against a floor that is a quarter inch higher at one corner than the other.
06How to replace a bottom seal
For a retainer-style seal, this is a twenty-minute job and one of the few garage door repairs we are happy to see homeowners do themselves. Nothing here is under spring tension.
- Close the door and unplug the opener. You are working at floor level along the bottom edge; you do not want the door moving.
- Identify the type and measure. Confirm the end profile from the table above and the T stem size. Note the flat width. Buy the same width unless the old seal was clearly too narrow for the gap.
- Pull the old seal out. Slide it out of one end of the retainer. If the retainer ends were crimped shut, open them with pliers. Old vinyl often breaks up; pull the pieces and clear the channel with a flat screwdriver.
- Clean the retainer. Grit in the channel is what makes a new seal fight you. Wipe it out, then spray the channel and the new seal's T ends with soapy water or a silicone lubricant.
- Feed the new seal in. Start both T ends into the channel at one end and walk it across. A helper on the far end pulling gently while you feed makes a 16 foot seal easy. Do not stretch it: a stretched seal shrinks back over the first summer and leaves a gap at the end.
- Trim and secure. Cut flush with the door edge plus about 1/2 inch, then crimp the retainer ends slightly or add a screw so the seal cannot walk out.
- Test. Plug the opener back in, close the door, and look for daylight from inside with the garage lights off. Then run it a full cycle and confirm the door reaches the floor without reversing.
Nail-on seals on wood doors follow the same idea with a pry bar and galvanized nails: pull the old flap, cut the new one to width, and nail it along the bottom edge with the flap curling toward the inside of the garage. If the bottom of the wood section is soft or rotted, that is a section replacement conversation before it is a seal conversation.
07Perimeter weather stripping
The seal most homeowners never think about runs up both sides of the opening and across the top: vinyl stop molding, a rigid PVC or wood strip with a flexible flap along its edge, nailed to the jambs so the flap presses against the closed door's face. When it hardens or pulls away you get the classic thin line of light down each side of the door and a draft you can feel with the door shut.
Replacing it is a nail-and-cut job:
- Sold in 7 foot side pieces and 9 or 16 foot top pieces to match standard openings, or in longer sticks to cut down.
- Set each piece so the flap just touches the door face with the door closed. Too tight and the door drags and scuffs; too loose and it seals nothing. The usual method is to close the door, press the molding until the flap folds slightly against the door, and nail it there.
- Do the top piece last so it overlaps the sides at the corners.
- Colors are limited, usually white, brown, and almond, and the strip can be painted with exterior paint if you want it to match trim.
Stop molding also hides the gap between the door and the framing, which is why a door with fresh molding looks newer than the same door without it.
08Threshold seals
A threshold seal is a 1/2 to 1 inch tall rubber ramp glued to the garage floor directly under the closed door. The bottom seal closes down onto it instead of onto the bare slab. It is the right answer to three specific problems:
- Water running in from the driveway. Where the driveway slopes toward the garage, sheet water flows under any bottom seal. The threshold is a dam.
- An uneven or cracked slab. The threshold gives the seal a straight, level lip to close against.
- Pests and leaves. The threshold plus a good bottom seal closes the gap that leaf litter and rodents use.
Two cautions. Once glued down, a threshold is permanent and cannot be swept over, so debris that lands inside stays inside until you pick it up. And a threshold does not fix a door that is out of level or a bottom section that is bowed. If one corner of the door is an inch off the floor and the other touches, the door needs adjusting or the floor needs looking at, and no amount of rubber will hide it. Metro techs will tell you which it is on a tune-up visit rather than selling you a threshold you do not need.
09Signs a seal is done
Stand inside the closed garage with the lights off in daylight. What you see tells you which seal has failed:
- A line of light along the floor the full width of the door: the bottom seal has flattened or hardened. If the light is only at one end, the floor slopes and a wider seal or a threshold is the fix.
- Thin lines of light down the sides or across the top: the perimeter stop molding has pulled away or the flap has hardened.
- Light through the door itself between sections: section joints are worn or the door is an old flat-joint design. Some doors accept a joint seal; on others the answer is a newer door with a proper shiplap joint.
- Cracks or chunks missing from the bottom seal, or a seal that has slid so one end no longer reaches the edge: replace it.
- The door reverses an inch off the floor: either the bottom seal is too tall for the force setting, or the seal is fine and something else is going on. Start with our troubleshooting guide before buying parts.
10What Georgia weather does to seals
Metro Atlanta is hard on garage door seals in a specific way. Summers cook the bottom of a west or south facing door for hours, which is what turns a flexible vinyl seal into a brittle one that cracks along its fold. Humidity works on the retainer and the bottom section behind it, and a corroded retainer is the usual reason a seal that "should slide right in" will not. Then the winter cold snaps arrive and a seal that hardened over the summer no longer compresses, so the first daylight under the door tends to show up in December.
Three practical adjustments for this climate:
- Choose rubber or TPE over vinyl on doors that face the afternoon sun. The price difference is small against a seal that lasts twice as long.
- Check the seal every fall. It takes thirty seconds with the door closed and the lights off, and a bottom seal is far cheaper than the water damage or the pest problem it prevents.
- Pair seals with an insulated door if the garage has living space over it. Seals stop the air movement; insulation stops the heat transfer. Our insulated garage doors page covers the R-value side, and the annual tune-up covers the seals every year.
Metro has been sealing, servicing, and replacing metro Atlanta's garage doors since 1979 from two locations, Douglasville and Alpharetta. Every visit is a W-2 Metro tech in a Metro truck, and every price is written before the work begins.
FAQ
How do I know which garage door bottom seal I need?
Look at the bottom edge of the door. An aluminum channel with a strip sliding into it is a retainer, and the shape of the strip's ends tells you the type: a T on each end is a T-end seal, a round bead is a bead seal, a single round tube is a bulb seal, and two hooked ends make a J-type. No channel at all, just a rubber flap nailed to the wood, is a nail-on seal. For T-end seals measure the width of the T stem, either 1/4 inch or 5/16 inch, and the flat width of the old strip, then match both. When in doubt, cut a 2 inch sample off the old seal and take it to the counter with you.
What size garage door bottom seal do I need?
Match the T size to your retainer, then pick the width by the gap. A floor that meets the door evenly takes a 3 to 4 inch wide seal. A floor that slopes away at one side or has a 1/2 inch or larger gap wants a 5 or 6 inch seal, which compresses more before daylight shows. Length is the door width plus a couple of inches to trim, so 9 or 10 feet for a single door and 16 or 18 feet for a double. Standard door widths are listed in our garage door sizes guide.
How long does a garage door bottom seal last?
Vinyl seals last about five to ten years in metro Atlanta, less on a south or west facing door that cooks all afternoon. Rubber and TPE seals stay flexible longer, often into the ten to fifteen year range. The seal is done when it has hardened, cracked, flattened, or torn at the ends, and by that point it stops sealing long before it falls off.
Can I replace a garage door bottom seal myself?
Usually, yes, and it is one of the few garage door jobs we tell customers is safe to do themselves. A retainer-style seal slides out and the new one slides in with a little soapy water; the whole job is twenty minutes with the door down and the opener unplugged. The exceptions are a bent or corroded retainer that needs replacing, a nail-on seal on a heavy wood door, or a door that has to be raised and blocked to work under, all of which we handle during a tune-up.
Why does water still get under my garage door with a new seal?
Because the seal is not the problem, the floor is. Garage slabs settle, crack, and slope toward the driveway, and a bottom seal can only compress so far. A threshold seal glued to the floor gives the bottom seal a raised lip to close against and stops sheet water running in. Where the gap is uneven side to side, a wider seal plus a threshold usually solves it. Where the slab has heaved, that is a concrete conversation before it is a door conversation.
Does the garage door seal affect my energy bill?
It affects the garage, and by extension any room over or beside it. The bottom seal and perimeter stop molding are the difference between a garage that holds temperature and one that breathes with the weather. Pair them with an insulated door and the garage becomes a usable buffer zone; skip them and even an insulated door leaks around its edges. Our insulated door page explains the R-value side.
Does Metro replace weather seals?
Yes. Weather seals are on the 22-point checklist for every Metro annual tune-up, and we replace bottom seals, retainers, perimeter stop molding, and threshold seals on any service visit. Prices are quoted in writing before work begins. Call (770) 526-1214 or book online and mention the seal when you schedule so the truck carries the right profile.
