Quick answer
Weatherstripping is the set of flexible seals that close the gaps around a garage door, chiefly the perimeter seal along the jambs and header, plus seals at the top, between sections and at the bottom edge.
DASMA defines a perimeter seal as weatherstrip installed at the perimeter of a garage door, and stop mould as trim, usually nailed to the jamb outside the door, that seals against weather and light. DASMA lists weather seals among the parts that resist heat flow.
Quick facts
The key facts about Weatherstripping, with sources:
- Perimeter seal (DASMA)
- Weatherstrip installed at the perimeter of a garage door 1
- Stop mould (DASMA)
- Seals the perimeter against weather and light; nailed to jamb 1
- Header seal (DASMA)
- Weather-stripping at the header 1
- Typical materials
- Flexible vinyl or rubber 6
- Thermal role
- Weather seals resist heat flow 2
- Water expectation
- Sectional doors are not watertight 5
Key takeaways
- Weatherstripping covers every gap around the door: sides, top, joints and bottom.
- The perimeter seal at the jambs and header is usually a stop molding with a flexible flap.
- It must press lightly on the closed door without dragging as the door moves.
- Good seals cut drafts, water, dust, pests and noise.
- No set of seals makes a sectional door watertight, DASMA says.
What weatherstripping is
DASMA uses weatherseal and weatherstrip as the same term, and names several kinds by position: the bottom weatherseal on the door’s bottom edge, the perimeter seal around the door, the header seal at the opening header, the top seal fastened to the top of the door, and the section joint meeting rail seal between sections 1.
Clopay describes perimeter seals, sometimes called weatherstripping, as running along the sides and top of the door frame to close the gaps around the door, usually made from flexible vinyl or rubber and attached to the frame with nails or adhesive.
Installed together with a bottom seal and a threshold seal, it says they create a full weather barrier 6.
Perimeter seal and stop molding
DASMA defines a perimeter seal as weatherstrip installed at the perimeter of a garage door 1.
On most homes it takes the form of stop mould: DASMA describes stop mould as serving to seal the perimeter of the door against weather and light infiltration, usually nailed to the jamb outside the door, and lists jamb seal, door stop and finish moulding as other names 1.
Modern stop molding is usually a rigid vinyl or composite strip with a soft flap or bulb along one edge.
It is nailed to the jambs and header so the flap presses gently against the outside face of the closed door.
Clopay’s jamb seal description makes the same point: the seal flexes as the door opens and closes while keeping contact with the door edge 6.
How perimeter seals work
A sectional door sits inside the opening, behind the jambs and header, and the sections usually overlap the jambs slightly. When the door closes, its outside face comes to rest against the soft edge of the stop molding. The flap fills the gap between the door and the frame along both sides and the top.
As the door opens, the top section moves back and away from the header and the sides slide past the jamb seals.
If the seal is set too tight, it drags, squeaks and can make the opener work harder. Too loose, and it does not touch the door at all.
DASMA’s wind-driven rain guidance recommends that sections overlap the jambs one inch per side where building conditions permit, and that trolley arm and top bracket adjustments be performed routinely, both of which help the perimeter seal do its job 5.
Kinds of garage door weatherstripping
| Seal | Where | DASMA or maker description |
|---|---|---|
| Perimeter seal | Around the door | Weatherstrip at the perimeter 1 |
| Stop mould / jamb seal | Jambs, outside the door | Seals against weather and light; nailed to jamb 1 |
| Header seal | Top of the opening | Seals between header and door 1 |
| Top seal | Top edge of the door | Fastens to the top of the door 1 |
| Section joint seal | Between sections | Weather seal between door sections 1 |
| Hinge seal | Between panels at hinges | Closes gaps as the door flexes 6 |
| Bottom seal | Bottom edge | Astragal 1 |
Example: how much seal a door has
For a 16 ft wide × 7 ft high double door with four sections, add up the seal lines.
| Seal line | Length | Notes |
|---|---|---|
| Jambs (2 sides) | 2 × 7 ft = 14 ft | Stop mould 1 |
| Header | 16 ft | Stop mould or header seal 1 |
| Bottom | 16 ft | Astragal 1 |
| Section joints (3) | 3 × 16 ft = 48 ft | Joint profile, maybe a seal 1 |
| Total | 94 ft | Over half of it at the joints |
That is why joint design and perimeter seals matter as much as insulation. See section joint.
Where you see it
Stand outside with the door closed. The stop molding is the trim strip along both sides and the top of the opening with a soft edge touching the door. Inside, you may see a top seal on the door’s top edge and seals at the joints on better insulated doors.
Old wood stop molding with a felt or rubber strip is common on older homes. Newer homes usually have vinyl or composite molding with a co-extruded flexible flap that resists rot.
Seals, energy and comfort
DASMA lists weather seals among the elements that resist heat flow through a door, in contrast to thermal shortcuts such as joints and stiles 2. Clopay advises strong perimeter weatherstripping and durable bottom seals to work alongside the door’s insulation and minimize air leakage 7.
Note what the official ratings leave out. DASMA’s thermal verification program covers U-factor but not air infiltration 4. A door with a good U-factor in a gappy opening still loses heat, so seal condition matters in your garage, not in the lab. See thermal bridging.
Seals and wind-driven rain
DASMA is blunt: sectional doors provide some protection against water but are not leak proof or watertight 5.
Rain can cling to the face and drip in when the door opens, collect in section interfaces and wick to the ends past the perimeter seal, or be driven through the sides, bottom and joints by strong wind 5.
DASMA’s advice to dealers includes seals between sections, enhanced perimeter seals at the top, bottom and sides, and an aluminum or rubber threshold with an enhanced bottom seal, noting that perimeter seals can be effective to some degree 5. For buildings, it recommends gutters, overhangs and a rain lip at the slab 5.
Seals and thermal bowing
Insulated doors bow slightly in strong sun or cold. DASMA reports field issues such as the top section rubbing the header with an outward bow, or a gap at the top with an inward bow 3.
It says other techniques depend on the adjustability of the track or the jamb and header seal, and to ask the maker for recommendations 3. A flexible header seal with enough reach can hide a small seasonal gap.
Pests, dust and security
Gaps at the sides and top are an easy way in for insects, mice, wasps and windblown leaves.
Clopay notes that gaps under and around a garage door are an open door for insects, rodents and debris, and that a well-sealed garage stays cleaner with less dust and pest activity 6.
Corners where the jamb seal meets the bottom seal are the usual weak spot, so check that the two overlap.
Clopay also points out that gaps and worn seals can create weak points that are easier for intruders to exploit, and that sound seals reduce those vulnerabilities 6.
A torn header seal, for example, can leave room to slip a tool over the top section toward the emergency release. Keeping the perimeter tight is a small, cheap step toward a more secure garage.
Benefits and limits
Limits
Weatherstripping seals gaps of a fraction of an inch to about an inch. Larger gaps mean the door, track or framing is out of line, and seals will not fix that. Seals also cannot stop water that pools against the door; slab design and drainage do that 5.
What drives cost
No prices on this page. See the cost guide.
- Material: vinyl, rubber or composite molding.
- Opening size.
- Enhanced seals for wind-driven rain 5.
- Labor if trim or jambs need repair.
How to replace perimeter seals
- Pull away the old weatherstripping gently with a pry bar or screwdriver 6.
- Clean the frame and measure each side and the top 6.
- Cut new strips to fit 6.
- Close the door and fasten each strip so the flap touches the door lightly 6.
- Check for light or drafts and adjust 6.
- Light at sides or top?
- Flap touching door?
- Drag or squeak?
- Cracked or brittle?
- Rotten wood trim?
- Water at the corners?
Upkeep
Warning signs
Light around the edges, leaves and water in the corners, cold drafts, or a flap that is cracked, brittle or curled away from the door all mean the perimeter seal has failed. A seal that suddenly drags may mean the door or track has shifted; have it checked.
Do not adjust tracks to fit a seal
If the door no longer meets the seals evenly, the cause is usually track, cable or spring adjustment. Leave those to a trained technician; adjust the seal, not the hardware.
Rules to know
DASMA notes US building codes traditionally have not included water infiltration requirements for sectional doors 5. Energy codes reference tested U-factor, which does not cover air leakage in your opening 4.
Perimeter seal vs bottom seal
Myths
Climate
West-facing doors in storm-prone areas need the best perimeter seals and overhangs, per DASMA’s rain guidance 5. Cold, windy places gain most in comfort from tight perimeter seals.
DIY or call a pro?
Replacing stop molding is usually a do-it-yourself job; Clopay suggests calling a pro for heavy or custom doors or major alignment issues 6. Combine it with a new bottom seal and a check of your maintenance routine.
Check at night
Turn on the garage light after dark and look from outside. Every glowing line around the door is a gap in the weatherstripping.
Questions about Weatherstripping
What is garage door weatherstripping?
The seals around the door: perimeter seals at the jambs and header, plus top, joint and bottom seals.
What is a perimeter seal?
Weatherstrip installed around the edges of a garage door. DASMA calls this a perimeter seal.
What is stop molding?
Trim usually nailed to the jamb outside the door that seals against weather and light, per DASMA.
What is the difference between a jamb seal and a header seal?
Jamb seals run up the sides; the header seal runs across the top of the opening.
How often should weatherstripping be replaced?
Most seals last 2–3 years before they need replacing, Clopay says, with climate and use deciding where in that range.
Can I replace weatherstripping myself?
Usually. Pull the old strips, measure, cut and nail new ones so the flap touches the closed door lightly.
Why does water still get in at the corners?
Water in the section joints can wick to the ends and slip past the perimeter seal, DASMA explains. Doors are not watertight.
Do seals save energy?
Yes. DASMA lists weather seals as resisting heat flow, and Clopay advises them alongside insulation.
Why is my new seal squeaking?
Most likely it sits too tight against the door. Reset it so the flap just touches.
Do seals help with noise?
Clopay says perimeter and bottom seals help absorb vibrations and keep the garage quieter.
What are hinge seals?
Seals between panels at the hinges that close gaps as the door flexes, per Clopay.
Sources
- DASMA Technical Data Sheet #160, Sectional Garage Door Terminology, retrieved .
- DASMA Technical Data Sheet #163, U-factor and R-value for Residential and Commercial Garage Doors, retrieved .
- DASMA Technical Data Sheet #185, Thermal Bowing of Garage Doors with Bonded Core Sections, retrieved .
- DASMA Technical Data Sheet #196, U-factor on Garage Doors and the DASMA Thermal Performance Verification Program, retrieved .
- DASMA Technical Data Sheet #1503, Wind-Driven Rain and Sectional Garage Doors: Reasonable Expectations, retrieved .
- Clopay, Garage Door Seals: A Buyer’s Guide, retrieved .
- Clopay, Guide to Insulated Garage Doors (R-value, U-factor, polyurethane vs polystyrene), retrieved .
Expert review
Written by the HyreGarage Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Seal definitions from DASMA TDS-160; thermal role from TDS-163 and TDS-196; water guidance from TDS-1503; bowing from TDS-185; materials and install from Clopay.
Suggest a correction. We fix errors and say what changed.