Ready to Get Started?
Our doors & millwork specialists can help you find the right products for your project.
Browse › Doors & Millwork
Garage Door Weatherstripping and Stops
How to Pick the Right Seal for a Montana Winter
Doors & MillworkA garage door has three places it leaks: the bottom, the two sides, and the top. Garage door weather stripping refers to the materials used to seal gaps around the edges of your garage door, typically installed at the bottom, sides, and top of the door to prevent outside elements from entering. Get the right material and match the existing profile, and you stop drafts, blowing snow, snowmelt, and mice cold. Buy the wrong profile, and you’ve wasted your money. That’s the whole job in two sentences.
For broader project planning, explore WBC’s doors and millwork resources.
This is a DIY-friendly fix. A garage door that isn’t properly sealed allows drafts, moisture, and pests to sneak in, making your garage uncomfortable and inefficient. Garage door weather stripping is an affordable and effective solution to these issues. Here’s how to choose and install it without the rookie mistakes.
The Three Seal Locations and What Each Does
Every garage door seal falls into one of these jobs. Know which one you’re buying before you spend a dime.
Bottom seals (door sweeps). This is the one most folks need first. Also known as door sweeps, these are long strips of rubber or vinyl attached to the bottom of your garage door to seal the gaps between the door and the floor. They ride in a retainer. Door sweeps are relatively easy to install using a steel, aluminum or PVC retainer. However, if you have a wooden garage door, you may need an aluminum or galvanized fastener to make your door compatible with them.
Perimeter seals / stop molding. These run up the sides and across the top. These seals run along the sides and top of your garage door. They help prevent cold air, dust, and insects from entering through the edges. Perimeter seals are typically made from foam or rubber and provide a tight seal. One honest limitation: they may not be as effective on older doors with misaligned tracks. Fix the door first, then seal it.
Threshold seals. This one bonds to the floor, not the door. Unlike door sweeps, threshold seals are attached to the floor instead of the garage door. They fill the gaps between the floor and garage door but often must be combined with a bottom seal to keep out all the elements. The reason to reach for one: threshold seals are made from durable rubber, vinyl or aluminum, making them solid and sturdy enough to drive over without damage. They’re the best if your garage door meets the floor asymmetrically or the driveway slopes toward the garage. Plenty of Montana driveways slope right back at the building. That’s where threshold seals earn their keep.
Tension seals (V-strips). A lower-profile option for sides and top. Also known as the V strip, it’s weatherstripping shaped like a V to create a tight seal along the garage door’s length. They’re available in aluminum, copper or stainless steel materials shaped to securely attach to the sides and top of the garage door. The catch: when properly installed, they are invisible and blend into many surfaces. However, they can only be installed on flat and smooth surfaces and may increase the garage door’s resistance.
Material Choice Is the Whole Ballgame in Cold Country
This is where Montana buyers go wrong. The wrong material gets hard and cracks the first time it hits twenty below. Pick for the climate, not the price tag.
| Material | Cold-weather behavior | Notes |
|---|---|---|
| EPDM rubber | Stays flexible in extreme cold | One bottom-seal kit is rated flexible to -50°F |
| Rubber (general) | Stays flexible for extended periods | Available in different densities and thicknesses; the best choice for areas with freezing winters |
| Vinyl | Can stiffen when cold | Cheaper; resists mold and mildew |
| Silicone | Stays flexible in extreme conditions | Superior at blocking air, water, dirt and dust; highly durable |
| Metal (coated steel/aluminum) | Built for heavy snow | Needs rust-resistant coating |
| Co-extruded PVC | Brittle when bent | Rigid backing with a flexible flange |
Rubber is the classic pick here for a reason. Rubber is a classic weatherstripping choice, available in different densities and thicknesses to suit different climates. It’s the best choice for areas with freezing winters because it remains flexible for extended periods. EPDM takes that even further — one professional bottom-seal kit uses an EPDM synthetic rubber seal engineered to remain flexible in extreme temperatures down to -50°F, providing reliable protection against air, dust, pests, and moisture. That double-walled design also offers enhanced durability and resistance to damage, making it suitable for demanding environments.
Vinyl has its place. It’s cheaper, and it still offers excellent protection against drafts and moisture. Plus, vinyl weather stripping tends to be more resistant to mold and mildew than rubber. But know its limit — vinyl is great for keeping drafts and moisture out, resistant to mold and mildew growth, and ideal for installation in rainy, humid or windy climates. Mild and wet is its sweet spot, not deep cold.
Heavy snowfall changes the math. If you live in an area with heavy snowfall, metal weather stripping might be the way to go. It’s incredibly durable and can withstand heavy use. Look for metal stripping with a rust-resistant coating to ensure it lasts for years to come.
One word on PVC stop molding: it’s stiff backing with a soft flange, and it does not like being bent. PVC weatherstripping is brittle, and breaks easily when bent. Handle it accordingly.
Match the Profile and Size Before You Buy
Bottom seals are not one-size-fits-all. The seal slides into a retainer with a specific shape, and the wrong shape simply won’t seat.
Identify what you’ve got first. Snip off a short sample of the old seal or shoot a clear photo of the end profile, then match it. Bottom-seal kits are built around door thickness and width. The EPDM kit referenced here fits 9’ or 18’ doors in 1-3/8”, 1-3/4”, or 2” thickness and uses a T-End (1/4”) track type — that’s your retainer profile right there. Its other specs:
| Spec | Value |
|---|---|
| Seal width | 4.2” |
| Material | EPDM synthetic rubber |
| Door thickness options | 1-3/8”, 1-3/4”, 2” |
| Track type | T-End (1/4”) |
| Kit lengths | 9’ or 18’ (cut to size) |
| Retainer sections | 4’6” aluminum |
| Included | Seal, retainer, mounting screws, rubber stoppers |
Stop molding sells as a set. Rolled garage door side and top stop molding comes cut to your specific size, made of co-extruded flexible and rigid PVC. A typical kit includes two pieces for the sides and one piece for the top of your door, cut to your specified length. Order it against your door’s dimensions — common sizes run 9x7, 18x8, and 20x10. If you have an odd size door, order the next size up and trim the door stop to fit.
On the retail shelf you’ll also see straight-stick stop, like a 1/2” x 2” x 9’ white garage door stop — a single length you cut down to suit the opening.
Buy a little long. To determine how much weatherstripping you need, add the perimeters of all windows and doors to be weatherstripped, then add 5% to 10% to accommodate any waste. For a bottom seal in a climate that swings hard between seasons, leave roughly a half inch to an inch extra when cutting so the material can move with temperature.
Installation Basics and the Mistakes That Defeat the Whole Job
Three things ruin a seal: a dirty surface, a sloppy cut, and cracked PVC. Avoid those and this goes smooth.
Surface and timing. Give your garage floor a good sweep to remove any dirt or debris. This will help your new weather stripping adhere better. If the floor is oily or greasy, give it a wipe down with a degreaser. Weatherstripping should go on clean, dry surfaces above 20°F (-7°C). That temperature floor matters here — pick a mild day, not a cold snap.
Order of operations on stop molding. This is the detail most people miss. The order of installation is important. Install the top seal first, then the seals on either side so that they intersect with the top seal. This makes sure the top flap is behind the side flaps, which keeps the flaps from being torn.
Nailing PVC. Skip the nail gun. Nail guns and staplers are not recommended for this product. Use the nails provided and pre-drill holes about every 6”. And never swing a hammer at it while it’s flexed — be sure not to hammer the PVC weatherstripping while it is bent, since the material is brittle and this will likely break it. If a rolled product won’t lie flat, a heat gun may be used carefully to relax the product so it will flatten out.
Cut clean, measure twice. Mark the excess with a pen, take the seal down, and cut off the excess so it fits flush with the garage door frame. Use a tool that makes a straight, clean edge. On side pieces, length is everything — if it is too long, it will create a bubble and not seal properly.
Test it. Close your garage door and inspect the seal from inside. If you see any gaps, you can adjust the stripping as needed. The flexible flange should press lightly against the door face. On stop molding, close the garage door to check the seal — if installed properly, it should form a right angle with the flap. Then push on the door: if there is a gap when you push on the door, readjust the seal to remove it. As the wind blows, it will push the door back and let in a draft. This is especially problematic in winter, so it is important to remove any gaps.
The most common buyer error is simpler than any of this. Using the wrong type of seal for your climate, failing to clean the door before installing, and not measuring carefully — leading to gaps or mismatched materials. Don’t be that buyer.
When to Replace and What You Get for It
Weatherstripping is a wear item. It does not last forever, and a brittle seal is worse than no seal because it lulls you into thinking you’re covered.
Lifespan runs short. Weatherstripping typically lasts and remains usable for two to three years after installation. However, annual inspections are necessary to determine whether it’s still as effective as when it was first installed. Some folks replace on a preventive schedule instead — consider replacing your weather stripping every 5-10 years as a preventative measure.
Watch for these signs:
- You can see light shining through the bottom or sides when the door is closed
- You feel a draft when standing near the door, even on a calm day
- The seal feels brittle, cracked, or crumbling when you touch it
- Water pools under the door after rain, or snow drifts inside
- Dust and dirt accumulate faster than usual
- Your energy bill has gone up unexpectedly
The payoff is real, and it’s bigger here than in a mild climate. The obvious win is energy: by keeping cold air out and warm air in during winter, weather stripping helps your garage stay at a consistent temperature. This means your heater won’t have to work as hard, saving you money on energy bills. Then there’s what it protects. Weather stripping keeps rain and snowmelt from seeping into your garage. This helps prevent water damage and keeps your space dry and mold-free. If you store expensive tools or equipment, weather stripping is a must.
The Montana kicker is the freeze-thaw cycle. When water enters your garage, it freezes, causing ice damage to the floors and accelerating the door’s wear and tear. Water pipes running through the garage are vulnerable to bursting when exposed to extremely cold temperatures. A good seal at the bottom and threshold isn’t just comfort — it’s keeping water out before it can freeze and pry your floor apart.
And then there’s the mice. Gaps around your garage door are an open invitation for unwanted guests like mice, insects, and even small animals. Weather stripping helps to keep these pests out.
Frequently Asked Questions
How do I figure out which bottom seal profile I need? Pull the old seal and look at the end, or snip off a short piece to carry as a reference. The seal seats into a retainer with a matching shape — a kit built for a T-End (1/4”) track won’t fit a different profile. Match the retainer shape plus your door thickness (1-3/8”, 1-3/4”, or 2”) and width before ordering.
Rubber or vinyl for a Montana garage? Rubber, and ideally EPDM. Rubber is the best choice for areas with freezing winters because it remains flexible for extended periods. Vinyl is cheaper and resistant to mold and mildew, ideal for rainy, humid or windy climates — but cold is where it can stiffen up. One EPDM bottom-seal kit stays flexible to -50°F.
What’s the difference between a bottom seal and a threshold seal? A bottom seal mounts on the door and moves with it. A threshold seal bonds to the floor. Threshold seals fill the gaps between the floor and garage door but often must be combined with a bottom seal — they’re the best if your garage door meets the floor asymmetrically or the driveway slopes toward the garage. For a sloped driveway, use both.
Why install the top stop molding before the sides? So the flaps overlap the right way. Install the top seal first, then the sides so they intersect with the top seal. This keeps the top flap behind the side flaps, which keeps the flaps from being torn.
Can I use a nail gun on PVC stop molding? No. Nail guns and staplers are not recommended — use nails and pre-drill holes about every 6”. And never hammer PVC while it’s bent; it’s brittle and will crack.
How often should I replace it? Inspect annually. Weatherstripping typically lasts two to three years. Some replace every 5-10 years preventively. If you see daylight under the door, feel a draft, or the seal crumbles when you touch it, it’s done.
What temperature do I need to install in? Apply to clean, dry surfaces above 20°F (-7°C). Cold concrete and a hard freeze fight you on adhesion and make PVC even more brittle. Wait for a mild day.