Window Capping Replacement in Toronto and the GTA

• Recapping fixes the outside trim; it does not fix fogged glass, drafty sashes or broken hardware.
• Old capping comes off first so the wood underneath can be checked and repaired if soft.
• The sill is the critical piece: it needs outward slope and a drip edge so water falls clear.
• Brick and siding walls are detailed differently at the joint where capping meets the wall.
• Recapping is the easiest moment to change trim colour, such as white to black.
• Ballpark: $175–$450 per window, plus $150–$900 per opening if rot repair is needed (2026).

9 signs your window capping needs replacing

Replace window capping when it no longer keeps water out or when it visibly drags down the look of the house. Cosmetic issues can wait; anything that lets water reach the wood should not. Here is what to look for on a walk around your home.

1. Water stains on the inside wall or sill

Brown marks on drywall below a window corner, or a damp interior sill after a storm, often trace back to an exterior joint that has opened. This is the most urgent sign on the list.

2. Caulk that has cracked, shrunk or pulled away

Run a fingernail along the joint where capping meets brick or siding. If the bead is hard, cracked or has a visible gap behind it, water is getting in. Re-caulking can buy time, but repeated failure usually means the capping is moving or badly fitted.

3. A sill that holds water

After rain, look at the sill. Standing water, dirt rings or green growth mean the sill wrap is flat or tilted back toward the house. That piece needs to be rebent with proper slope.

4. Soft or spongy wood behind the metal

Press gently on the capping at the lower corners. If it gives, bulges or sounds hollow, the wood behind it may be rotting. Frame repair comes before new capping; how rotted window and door frames are repaired is explained separately.

5. Dents and creases from hail, ladders or balls

Dents are mostly cosmetic, but sharp creases can split hems and open seams. Several dented pieces on one window make replacement cheaper than spot repairs.

6. Chalky, faded or patchy colour

Rub the surface with a dark cloth. A heavy white residue means the finish is breaking down. South and west elevations fade first, so one side of the house can look decades older than the other.

7. Lifting corners and loose nails

Nails driven tight eventually work loose as aluminum expands and contracts. Lifted corners catch wind and let rain behind the metal.

8. Wasps, ants or birds using the gaps

Insects nesting behind capping are a sign that openings are large enough for water too. Carpenter ants in particular like damp wood.

9. Capping that no longer matches

New siding, new windows or a new roof can leave old capping looking out of place. That is a purely visual reason, but a common one.

Recapping vs full window replacement: which do you need?

Recap when the window unit still works and only the outside trim has failed. Replace the window when the glass, seals or sashes have failed, because new capping on a failing window is money spent twice. The table below compares the two.

A quick decision test

Open and close each window, check for fogging between panes, and feel for drafts on a windy day. If the units pass, recap. If several fail, talk to a window supplier first and plan capping as the last step after installation. Pro Aluminum Siding does not supply or install windows; we do the aluminum work that finishes them.

The middle option: repairing capping instead of replacing it

Not every tired window needs full recapping. When the wood is sound and only one or two problems show up, a targeted repair can be the right call. Common repairs include:

• Re-caulking. Old sealant is cut out completely, the joint is cleaned, and a new bead is applied over backer rod where the gap is deep. Smearing new caulk over old rarely lasts a season.
• Refastening. Loose pieces are reset with proper aluminum or stainless nails in slightly oversized holes, so they can move without popping again.
• Single-piece replacement. A dented sill or torn side piece can be rebent and swapped on its own, as long as the colour still matches the pieces staying in place.

Repairs stop making sense when several pieces on the same window have failed, when the finish is chalking badly enough that new pieces would stand out, or when the sill has the wrong slope. In those cases, recapping the whole window costs little more and solves the cause.

Capping after new windows go in

New windows almost always need new exterior capping. Removing old windows usually damages the old capping, and the new units rarely line up with the old trim lines exactly.

What window installers leave behind varies. Some leave raw wood brick mould or bare framing with expanding foam showing around the frame. Some bend basic capping themselves. Others leave a temporary finish and expect a separate trade to finish the outside. Ask your window company exactly what “exterior finishing” includes before you sign with them.

Timing it right

• Book capping for soon after installation. Exposed foam degrades in sunlight and bare wood starts absorbing water immediately.
• Let any interior trim and insulation work finish first so the frame is not shifted after capping.
• Confirm the new window’s frame colour before ordering coil. Black and bronze frames vary between manufacturers.
• If siding is also being replaced, coordinate so trim and siding are done together. Our siding replacement service can be scheduled in the same visit.

What we check on a fresh install

We look at how the window is shimmed and foamed, whether the head has a drip cap or flashing, whether there is any sill pan or sloped sub-sill, and how much of the old brick mould remains. If something critical to drainage is missing, we tell you before covering it.

How old window capping comes off and new capping goes on

Replacing capping is a remove, inspect, repair, refit sequence. Skipping the inspection is the most common shortcut, and the most expensive one later.

1. Photograph and measure the existing trim. Before anything comes off, we record the layout so the new pieces respect existing siding laps and reveal lines.
2. Cut old caulk and pull the old capping. Sealant is sliced free and nails drawn so the surrounding brick or siding is not damaged. Old metal is taken away for disposal or recycling.
3. Probe every wood surface. Sills, the bottom of side jambs and the head are tested for soft spots. Anything soft is flagged and shown to you with a price before repair.
4. Repair, dry and prime as needed. Rotted sections are cut out and replaced with sound material. Bare wood is primed so it stops absorbing water.
5. Seal the frame-to-wall gap. Open gaps between window frame and rough opening are filled with low-expansion foam or backer rod so the new capping is not the only air barrier.
6. Bend and fit the sill first. The sill piece goes on before the sides, with outward slope and a drip edge, so side pieces lap over it like shingles.
7. Fit the sides, then the head. Side pieces overlap the sill; the head overlaps the sides. Water running down always passes over a joint, never into one.
8. Caulk the right joints, leave the drainage paths open. Perimeter joints to the wall are sealed; drainage points at the bottom are left clear.
9. Final walk-through. We check reveals, test for loose pieces and look at the sill drip line with you before leaving.

What happens to caulking and drainage when capping is replaced?

All the old caulk comes out, and new sealant goes only where it does a job. Window drainage depends as much on which joints stay open as on which are sealed.

Joints that get sealed

• The vertical joints where side capping meets brick or siding.
• The head joint, unless a separate flashing or drip cap sheds water over it.
• Where capping meets the window frame itself, so water running down the glass stays on the face of the metal.

Joints and openings that stay open

• Weep holes in the window frame. Most modern vinyl windows have small slots at the bottom of the frame to let water out. Caulking or capping over them traps water inside the window.
• The underside of the sill drip. The bent drip edge needs a clear gap below it so water falls off instead of running back toward the wall.
• Brick weeps below the window. In brick walls, small openings in mortar joints let water out of the cavity. They should never be sealed shut.

Why old caulk fails

Most failures we see are caulk applied in a thin smear over a wide gap, or bonded to three sides of a joint so it cannot stretch. A correct joint has a backing and a bead shaped like an hourglass, bonding to the two surfaces it connects. Our aluminum capping guide compares sealant types in more depth.

Sill pans, slope and the head drip: getting water off the window

Every window should shed water outward at three levels: the head, the sill surface and, ideally, a pan below the window. Capping replacement is a good time to check all three.

How to check your sill slope

1. Place a short level across the sill, front to back, on a dry day.
2. The bubble should show a fall toward the outside. Flat or back-sloped sills hold water against the window frame.
3. Pour a cup of water on the sill and watch where it goes. It should run off the front edge, not toward the house or into a corner.
4. Look under the front edge of the sill for a drip line. Without one, water clings to the underside and runs back to the wall.

What a sill pan does

A sill pan is a waterproof tray or membrane under the window, with upturned ends and back, that catches any water getting past the window and directs it outward. Many older GTA windows were installed without one. A pan can only be added properly when the window itself is removed, so it is a conversation to have with your window supplier at replacement time. For recapping existing windows, the capping is detailed to do the best job possible on top of what is there.

The head drip

At the top of the window, a drip cap or head flashing sheds water running down the wall above. When recapping, we bend the head piece with a forward kick so water drips clear of the window frame. If a separate head flashing exists, the capping tucks under it, not over it.

End dams on the sill

Where the sill meets side trim, water can run sideways into the corner. Small upturned folds at the sill ends (end dams) stop that. They take a few extra minutes to bend and are worth every one.

Window capping on brick walls vs siding walls

The capping itself is similar; what differs is where it meets the wall. On brick, capping ends at a sealed joint against masonry. On siding, it integrates with the siding’s own trim system.

Brick-specific tips

Brick is rarely flat, so a sealant joint against it has to be wide enough to fill the irregular edge without being smeared. Stone or precast sills below the window are left exposed and are not capped; only the wood above them is.

Siding-specific tips

On siding walls, damaged J-channel is often replaced together with the capping. If your siding is old and the window trim needs work on every window, compare the cost of recapping alone against a full siding job that includes new trim.

Changing colour: white to black and other updates

Recapping is the cheapest way to change the colour of your windows from the outside. Black, charcoal and bronze trim on brick homes is a popular update across the GTA, and it can transform a house built decades ago.

What to decide before switching to dark trim

• Your window frames. If the frames stay white and only the capping goes black, you get a two-tone look: a white frame line inside black trim. Some homeowners like it; many don’t. Look at a photo mock-up first.
• Heat and movement. Dark finishes get hotter in direct sun than white ones, so expansion is greater. Correct fastening matters more with black trim.
• Caulk colour. White caulk on black capping looks unfinished. Colour-matched sealant is available for most popular coil colours.
• Consistency. Doing only the front windows in black leaves white trim on the sides and back. Decide whether visible side elevations will be done too.
• Other trim. Door frames, garage openings and fascia look odd in a different colour than new window trim. Garage openings have their own page on capping garage door frames.

Matching new black windows

Black is not one colour. Window manufacturers’ blacks range from true black to near-charcoal, with different gloss levels. We compare coil samples against the actual frame in daylight before ordering.

Toronto data that matters for window trim

Public data on Toronto’s homes and weather explains why window capping wears out and why drainage detailing matters. Here are the figures we find most relevant.

• Most homes predate modern window details. Going by Toronto City Planning’s 2021 Census housing summary, only about a quarter of occupied dwellings (adding the 2001–2005, 2006–2010, 2011–2015 and 2016–2021 groups: 5%, 6%, 7% and 7%) were built in 2001 or later. The rest are older, with many original or second-generation windows.
• Heavier single-day downpours. The City’s climate report projects that maximum one-day precipitation will rise about 11% by the 2030s and 17% by the 2050s compared with the 1980s, under a very high emissions scenario. More intense rain tests every sill and head joint.
• Big rain days becoming more common. The same report expects days with about 68 mm or more of rain, its 90th-percentile threshold, to become more frequent.
• More hot days. Toronto averaged about 9.7 days above 30°C per year in 1961–1990 and about 14 in 1991–2020, per the report. Hot days mean more heat stress on dark trim and on sealants.
• Permits. The City of Toronto’s permit guidance says replacing windows in a house with one dwelling unit does not need a building permit as long as the opening keeps its size and position and structure is unaffected; enlarging or relocating openings does. Outside Toronto, every municipality sets its own requirements, and your city’s building office has the final word.

Window capping cost per window in the GTA

Window capping in the GTA typically costs $175–$450 per window as a ballpark (2026). Rot repair, if needed, adds $150–$900 per opening. Your written quote after an on-site measure is what counts.

What moves the price per window

• Window size and shape (bays, bows and wide picture windows need more pieces and bends).
• Sill and brick mould complexity.
• Storey height and access (ladder vs scaffold, landscaping, roofs below).
• Removal and disposal of old capping.
• Rot found once old capping is off.
• Coil colour and gauge.
• Season and scheduling.

Budgeting for multiple windows

The range applied to a house is simple arithmetic. Eight windows at $175–$450 each works out to $1,400–$3,600. Fifteen windows works out to $2,625–$6,750. Doing all windows in one visit is usually more efficient than a few at a time, because setup and colour matching happen once.

Example project scenario: recapping after new black windows

Spring and fall checklist for your window capping

• Look at every sill after a rain for standing water or dirt rings.
• Check caulk joints at the brick or siding for gaps or cracking.
• Press lower corners of the trim for softness or bulging.
• Look inside for any new stains below windows.
• Make sure window weep slots are clear of debris and paint.
• Clean eavestroughs above windows so overflow doesn’t pour down onto the head trim; see our eavestrough service if they overflow.
• Wash capping with a sponge and diluted dish soap; skip the pressure washer.
• Note any lifted corners or loose nails and have them refastened before winter.

Compare window recapping quotes with this worksheet

To get your own quote, call (647) 699-3330 or send photos of a few windows through our free estimate form. Our crews work across the GTA, from North York and East York to Brampton and Oakville.