Garage Door Stop Molding & Brick Mould: The Wood Trim Around Your Door, Why It Rots in Ontario & When to Repair or Replace It

Introduction

Most of the attention a garage door gets goes to the moving parts: the springs, the opener, the rollers, the cables. The part almost nobody thinks about until it fails is the strip of wood trim that runs up both sides of the opening and across the top. On the inside face, pressed against the door, it is called the stop molding or door stop. On the outside, the wider board that finishes the frame against the brick or siding is usually the brick mould. Together they are the quiet workhorse of your doorway: they close the gap between the door and the wall, they carry the weatherstrip that keeps wind and water out, and they are the first thing a passer-by sees framing your door.

In southern Ontario, this trim also happens to sit in the single worst spot on the whole house for rot. It is low to the ground, it takes splashback off the driveway, it gets buried in snow and road salt all winter, and it goes through dozens of freeze-thaw cycles a season. So it is no surprise that soft, spongy, peeling, or gap-riddled door trim is one of the most common things our technicians flag on a service call. This guide explains what the trim actually is, why it fails here specifically, how to tell whether yours needs a simple repair or a full replacement, what to replace it with, and the real 2026 numbers you should expect in the London area. Every external link has been checked against a live page on a recognized industry body or manufacturer resource.

What Is Stop Molding, and How Is It Different From Brick Mould?

The terms get used loosely, and it is worth pinning them down because they describe two different boards doing two different jobs.

Stop molding (the door stop)

Stop molding is the narrower strip nailed to the inside edge of the jamb, running up both sides and across the header. It is the board the door actually closes against. Its job is to stop the door in the right plane and, on almost every modern installation, to hold the flexible weatherstrip that presses against the face of the closed door. The Door & Access Systems Manufacturers Association, in its Technical Data Sheet TDS-160 on sectional garage door terminology, defines the jamb as the vertical member on each side of the door opening and the weatherstrip as the material used to seal the perimeter of the opening. The stop molding is what carries that perimeter seal. When people say their garage door trim is rotten, nine times out of ten they mean the stop molding, because that is the board sitting closest to the weather.

Brick mould (the exterior casing)

Brick mould is the wider, thicker profile that trims the outside of the opening where the frame meets the brick veneer or the siding. It is more decorative than functional, but it is far from cosmetic only: it caps the gap between the door frame and the wall cladding, and it keeps water from running behind the frame and into the wall assembly. On a brick house, the brick mould is what butts up against the masonry opening. On a sided house, a flat casing board often does the same job. Because brick mould stands proud of the wall, its bottom end catches and holds water, which is exactly why the bottom few inches are usually the first part of the whole doorway to rot.

How they work together with the weatherstrip

Think of the three as a team. The brick mould seals the frame to the wall. The stop molding positions the door and holds the weatherstrip. The weatherstrip itself, a vinyl or rubber flap, does the actual sealing against the moving door. If the wood behind the weatherstrip goes soft, the fasteners lose their grip and the seal stops pressing evenly, so you get drafts and blowing snow even though the rubber itself looks fine. That is why a weatherstrip problem and a trim problem are so often the same problem. Our guide to jamb seals and weatherstripping covers the rubber side of the equation; this article is about the wood the rubber depends on.

Why This Trim Matters More Than It Looks

It is easy to write off door trim as pure trim. In practice it is doing four real jobs at once, and letting it fail quietly costs more than replacing it does.

First, it is your primary weather seal against the sides and top of the door. A closed door with rotten stop molding leaks air along its whole perimeter. In a heated or attached garage, that is a comfort and energy penalty every winter day. Our cold weather garage door guide walks through how much difference a properly sealed opening makes when the temperature drops.

Second, it is a water barrier for the wall. Brick mould and casing keep rain and meltwater from getting behind the frame. Once water is in the wall cavity, you move from a fifty dollar trim board to a framing and drywall problem. This is closely related to the water-management issues we cover in our water under the garage door guide, just at the sides and top rather than the threshold.

Third, it is a pest barrier. Soft, gapped trim is an open invitation to mice, ants, and wasps looking for a way into the garage. A tight perimeter is one of the cheapest pest defences you have.

Fourth, it is the frame that makes the door look finished. Peeling, blackened, or crumbling trim drags down the look of an otherwise good door and takes a bite out of curb appeal, which matters if you are thinking about resale. Our curb appeal and resale guide puts numbers to how much the garage face contributes to first impressions.

Why Garage Door Trim Rots in Southern Ontario

This trim fails everywhere eventually, but our climate speeds it up. Four forces do most of the damage, and they stack.

Freeze-thaw cycling

Wood swells when it takes on moisture and shrinks when it dries. In London we cross the freezing point back and forth dozens of times each winter. Every cycle, water that has soaked into the wood expands as it freezes, opening tiny cracks, then the wood dries and the cracks stay. Paint film cracks along with it. Over a few seasons those micro-cracks become open checking that drinks water like a sponge, and rot fungus moves in wherever the wood stays damp above freezing.

Road salt and splashback

The bottom of the trim sits right where the plough spray, the salted slush off your tires, and the driveway splashback all land. Salt is hygroscopic, meaning it pulls and holds moisture, so salted wood stays wet longer than clean wood. Salt also attacks the finish and the nails. The same corrosive winter environment that we describe in our rust prevention guide for the metal parts is working on the wood trim and its fasteners at the same time.

Ground contact and standing water

A surprising number of garage door trim boards were installed running right down to the concrete, or even a hair below the slab surface, with no gap. Concrete wicks moisture, and the base of the board ends up sitting in a puddle every thaw and every rain. End grain at the bottom of a board is like a bundle of straws: it soaks water straight up into the board. This is why rot almost always starts at the bottom and climbs, and why you will often find the top eighteen inches of a board perfectly sound while the bottom six inches crumbles in your fingers.

Sun, condensation, and neglect

South and west-facing trim takes a UV beating that breaks down the paint film faster, and once the paint fails the wood is exposed. On the inside, a garage with a chronic condensation problem, the kind we cover in our garage door condensation guide, keeps the back of the stop molding damp for hours at a time in winter. Add the simple fact that nobody repaints garage trim on schedule, and you have the recipe for the peeling, soft-bottomed boards our technicians see every week.

The Warning Signs Your Trim Needs Attention

You do not need tools to catch most of these. Walk out to the door, look, and press.

• Peeling, blistering, or flaking paint, especially in the bottom foot or two of the side boards. Failed paint is the first stage, and it is your cue to act before bare wood starts drinking water.
• Soft or spongy wood. Press the board firmly with your thumb, or the eraser end of a pencil, near the bottom. Sound wood is hard. If it gives, dents, or feels punky, rot has started under the paint even if the surface still looks painted.
• Dark staining or a mushroom-like smell, both signs of active rot fungus in the wood.
• Visible gaps between the door and the stop, or daylight showing along the sides or top of the closed door from inside the garage. A gap means the weatherstrip is no longer pressing, often because the wood behind it has moved or softened.
• Drafts, blowing snow, or water intrusion along the perimeter of the closed door. If snow drifts in along the sides in a storm, the seal and the wood behind it have failed together. This is the side and top version of the sealing problems in our garage door seal guide.
• Loose or backed-out nails, or a stop board you can wiggle by hand. If the fasteners no longer bite, the surrounding wood has gone.
• Insect activity, tunnels, sawdust, or wasps working the trim, all of which favour soft wet wood.

Wood, PVC, or Composite: What to Replace It With

When trim has to come off, you get to choose what goes back on. This is the one moment where a small upgrade pays off for decades, because the failure mode you just fixed can be designed out.

Traditional wood

Primed finger-joint pine or spruce is the cheapest option and matches original trim on older homes. It paints well and is easy to work. Its weakness is exactly what caused the problem in the first place: it rots when it stays wet. If you replace like for like in wood, the clock starts again, and the new board will need diligent painting and a proper gap off the concrete to reach a normal service life. Solid cedar or a rot-resistant species does better than pine but costs more and still needs finishing.

Cellular PVC

Cellular PVC trim (brands such as Azek and Royal are common in Ontario) looks like painted wood, cuts and installs with ordinary tools, and simply does not rot because there is no wood fibre for water or fungus to attack. It is the upgrade we most often recommend for the bottom-of-the-opening boards that keep failing. It costs more per foot than pine, it expands and contracts with temperature so it needs to be fastened and gapped correctly, and it does not have to be painted, though it can be for colour. For a doorway that has rotted once already, PVC is usually the last time you will ever deal with it.

Composite and pre-primed engineered trim

Engineered options such as LP or Miratec composite trim sit between wood and PVC on both price and performance. They resist rot and insects far better than solid wood, come pre-primed, and paint cleanly. They are a reasonable middle path when you want better durability than pine without the full cost or the movement behaviour of PVC.

Whatever the material, the weatherstrip that mounts to it should be replaced at the same time. There is no sense fastening a fifteen-year-old brittle seal to a brand new board. The seal selection is covered in our jamb seals guide.

Repair or Replace? How to Decide

Not every soft spot means tearing off the whole board. The honest test is how far the damage has spread and how sound the wood around it is.

A repair makes sense when the rot is shallow and localized, the board is otherwise straight and firmly fastened, and the surrounding wood is still hard. Small areas can be dug out and rebuilt with a two-part epoxy wood filler, then primed and painted. A single failed lower corner on an otherwise good board is a classic repair candidate. Done properly, with all the punky wood removed and the repair sealed, this can buy several good years.

Replacement is the right call when the rot runs more than a few inches up the board, when the wood is soft enough that fasteners no longer hold, when the board is cupped or split along its length, or when you have already patched it once and it came back. At that point filler is just cosmetic over a board that has lost its structure, and the water is already getting past it into the wall. Replacing the board, ideally with PVC or composite at the bottom, solves it instead of hiding it.

A useful rule of thumb: if you can push a screwdriver into the wood with light hand pressure, that section is gone and no filler will bring it back. Fillers restore surface; they do not restore rotten fibre.

The Five-Minute Homeowner Inspection

Run this a couple of times a year, ideally once in spring after the salt season and once in fall before winter.

1. Stand back and look at the paint. Scan both side boards and the top for peeling, blistering, or bare wood, paying special attention to the bottom two feet of each side.
2. Press-test the bottoms. Firmly press the lower portion of each side board and the brick mould with your thumb. Note any spot that feels soft, spongy, or dents.
3. Check for daylight from inside. With the door closed and the garage light off, look along the sides and top of the door. Any daylight or draft means the seal, and likely the wood behind it, has an issue.
4. Look at where the boards meet the concrete. Is the bottom of the trim sitting right on or below the slab? Is there caulk that has cracked and pulled away? Water pooling at the base is the number-one rot cause.
5. Note and date it. Snap a phone photo. If the paint is failing but the wood is still hard, you have time to scrape, prime, and repaint. If the wood is soft, book a repair before winter drives water deeper.

This slots neatly into the broader seasonal routine in our garage door maintenance guide. Trim is one of those items that is cheap and easy to stay ahead of and expensive to ignore.

Can You DIY Garage Door Trim?

This is one of the more DIY-friendly jobs on a garage door, with one important boundary.

What is genuinely homeowner-safe: scraping and repainting weathered trim, filling a small rot pocket with epoxy filler, re-caulking the joint where the trim meets the brick or the concrete, and replacing a length of stop molding and its weatherstrip on the door face. None of that touches the counterbalance system. The stop molding sits on the frame, not on the spring shaft, so working on it does not put you anywhere near the stored energy that makes spring and cable work dangerous. If you are comfortable with a pry bar, a saw, and a caulk gun, a stop-molding-and-weatherstrip replacement is a reasonable weekend project.

Where it stops being a simple trim job: if the rot has spread from the trim into the structural jamb or the header the door tracks are anchored to, you are no longer trimming, you are into framing, and the door hardware bolted to that wood is now in question. Rot in the header behind the top brackets or spring anchor is a safety issue, not a cosmetic one. If pressing reveals soft wood behind where the tracks or the spring plate mount, stop and call a professional. That structural wood is what our garage door lifespan guide would call load-bearing, and it is not a paint-and-filler fix.

If you do repaint, do it right. Scrape to sound material, spot-prime bare wood, and use an exterior paint. The prep-and-paint fundamentals in the Family Handyman guide to painting a garage door apply just as well to the trim, and our own garage door painting guide covers colour and product choices for our climate.

Realistic 2026 Costs in Southern Ontario

Prices on this page are before HST.

Trim work is refreshingly affordable next to mechanical repairs, because the material is inexpensive and the labour is straightforward. Realistic 2026 numbers for the London area:

• Materials to replace the stop molding on one opening, wood, DIY: roughly $30 to $70 for the boards, plus $25 to $60 for new perimeter weatherstrip.
• Materials in cellular PVC or composite instead: roughly $70 to $150 for the boards on a single opening.
• Two-part epoxy wood filler for a spot repair: $25 to $50 for a kit that will do several small repairs.
• Professional replacement of stop molding and weatherstrip on a single door, supplied and installed: typically $200 to $400 depending on material and access.
• Professional replacement including brick mould or exterior casing as well: typically $350 to $650 for a single door, more for a double.
• Where rot has reached the structural jamb or header: this is quoted case by case after inspection, because it can involve framing repair and re-anchoring hardware.

Two notes on these figures. First, most door companies have a minimum service-call fee, so a small trim-and-seal job is often bundled into a tune-up visit for better value than a standalone trip. Second, the cost gap between putting back pine and putting back PVC is small next to the cost of doing the whole job again in eight years, which is the single best argument for the upgrade on the boards that keep failing.

How to Make New Trim Last

Whatever you install, a few habits stretch its life dramatically.

1. Keep the bottom off the concrete. The single most important detail. New trim should stop a small gap above the slab, and that gap should be sealed with a flexible exterior caulk, not left open and not run tight to the concrete. This breaks the wicking path that rots the bottom of the old board.
2. Seal the end grain. On wood, prime or seal the cut ends before installing. End grain is where water gets in fastest.
3. Repaint on a schedule. Inspect the finish every year and repaint wood trim every four to six years, sooner on the sun-beaten sides. Paint is the wood's raincoat.
4. Clear snow and salt away from the base. Do not pile shovelled, salted snow against the door trim. Clearing the base after a storm, and giving it an occasional rinse in spring, gets the salt off before it does its slow damage. The same seasonal care we describe in our rust prevention guide protects the trim too.
5. Fix the drainage. If meltwater pools at the base of the opening, address the grading or the driveway slope. Standing water is the root cause; a new board in a puddle rots too. Our water under the garage door guide covers the drainage side.

Common Mistakes Homeowners Make

Filling rotten wood instead of removing it

Epoxy filler is for small, sound-bordered repairs. Troweled over wood that is still soft and wet, it seals the moisture in and the rot keeps spreading underneath, invisibly, until the whole board fails. Dig out every bit of punky wood back to hard material before you fill, or replace the board.

Installing new wood tight to the concrete

The most common reason a replacement rots as fast as the original: the new board is run right down to the slab again, straight back into the puddle. Always leave and seal a gap at the bottom.

Replacing the seal but not the wood

A fresh weatherstrip nailed to a soft board will not press evenly and the nails will not hold, so the draft comes right back. If the wood behind the seal is gone, the wood is the repair, not the rubber.

Ignoring it because it is "just trim"

Trim rot does not stay trim rot. Left alone, water follows the wood into the jamb, then the framing, then the wall. A board you could have swapped for fifty dollars in materials becomes a framing repair. The whole point of catching it early is that early is cheap.

Assuming a soft header is a paint problem

Soft wood up at the top of the opening, where the spring anchor plate and top brackets are bolted, is not cosmetic. That wood is holding hardware under load. Treat softness there as a call-a-professional item, in the same spirit as the caution in our older and detached garage door guide, where original framing is often the weak link.

Frequently Asked Questions

What is the difference between stop molding and brick mould?

Stop molding is the narrow inside board the door closes against and that holds the weatherstrip. Brick mould is the wider outside board that finishes the frame against the brick or siding and keeps water out of the wall. A doorway usually has both, and both can rot, but the stop molding, sitting closest to the weather, tends to go first.

Is rotten garage door trim a safety problem?

The trim itself is not load-bearing, so surface rot on the stop molding is mainly a weather, water, and appearance issue rather than a danger. It becomes a safety concern only when the rot spreads into the structural jamb or header that the tracks, top brackets, or spring anchor are bolted to. If pressing reveals soft wood behind that hardware, stop using the door until a professional inspects it.

Can I just repaint over peeling trim?

If the wood underneath is still hard, yes, scraping and repainting is exactly the right move and will protect it for years. Paint over soft or rotten wood, though, and you are only hiding the problem while sealing moisture in. Press-test first: hard wood gets painted, soft wood gets repaired or replaced.

Should I replace the trim in wood or PVC?

For a doorway that has rotted once, cellular PVC or a composite at the bottom of the opening is usually worth the modest upcharge, because it cannot rot and you are unlikely to ever deal with that board again. Wood is fine if you match original trim and commit to keeping it painted and gapped off the concrete. The right choice depends on how much future maintenance you want to sign up for.

Why does my trim keep rotting at the bottom?

Because the bottom is where water collects and end grain wicks it upward. If the board runs tight to the concrete, splashback and meltwater sit against it and soak in. The fix is to stop the board a sealed gap above the slab, seal the end grain, and address any pooling water at the base of the opening.

Will new trim stop the draft and blowing snow along my door?

Usually yes, when the weatherstrip is replaced along with the wood. Drafts along the sides and top almost always trace back to a seal that is no longer pressing, and a seal stops pressing when the wood behind it has softened or moved. New sound trim plus fresh weatherstrip restores an even seal. Our jamb seals guide covers matching the right seal profile.

How often should I inspect the trim?

Twice a year is ideal: once in spring after the salt and thaw season, and once in fall before winter. A thirty-second press-test of the bottom of each board is enough to catch trouble while it is still a paint job rather than a rebuild. DASMA's homeowner maintenance guide is a good annual companion for the rest of the door.

Does homeowner's insurance cover rotten door trim?

Generally no. Rot is a gradual wear-and-maintenance issue, and insurance excludes gradual deterioration. It may cover sudden accidental damage, such as a vehicle strike, but slow rot from years of moisture is an out-of-pocket repair. The cheap insurance here is annual inspection and timely repainting.

Conclusion

The wood trim around your garage door does more than frame the opening. It seals out wind and water, keeps pests out, protects the wall behind it, and finishes the look of the whole door. In our salt-and-freeze-thaw climate it also happens to sit in the hardest spot on the house to keep dry, which is why soft, peeling, gap-riddled door trim is one of the most common things we find and one of the easiest to stay ahead of. Press-test the bottom of your boards a couple of times a year, keep the paint fresh, keep the base gapped off the concrete, and swap the boards that keep failing for PVC or composite instead of putting the same problem back. Caught early, this is a small job. Ignored, it turns into a wall repair.

If your garage door trim is soft, peeling, or letting in drafts and snow, our London-based team can inspect it, tell you honestly whether it is a repair or a replacement, and swap the wood and the weatherstrip together in a single visit. Call 519-619-7901, reach us through our contact page, or browse new doors and openers on our price estimator. AA Advantage Doors has been keeping London-area doors sealed, sound, and looking sharp since 2009; our BBB profile has the service history.