Concrete & Stone Window Sill Repair and Replacement
Cracked, crumbling or back-sloped masonry sills send water straight into your walls. We repair and replace concrete, precast, stone and brick window sills on homes across SW Ontario. Wood sills aren’t our trade; masonry ones are.
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Masonry Window Sill Repair & Replacement
A sill has one job: catch the water running off the window and throw it clear of the wall. When it can’t, the brick below pays for it.
Concrete Sill Repair
Cracks sealed, chipped and flaking areas rebuilt and the front edge restored, so a sound sill keeps working without being replaced.
Precast Sill Replacement
Badly cracked or crumbling sills cut out and replaced with new precast concrete, set on a full mortar bed and tied back into the brick.
Stone Sill Repair
Limestone and sandstone sills on older homes repaired, or replaced to match, with the joints repointed in a suitable mortar.
Brick Sills
Rowlock brick sills re-laid and repointed where bricks have loosened, cracked or started to tip.
Slope & Drip Edge
A sill that’s settled flat or tipped toward the window gets reset so water runs off the front and drips clear of the wall.
Joints Around the Sill
The ends and the bed joint under a sill are where water sneaks in. We check and repoint them as part of the job.
Concrete, Precast, Stone or Brick: Which Sill Do You Have?
Search “window sill repair” and you’ll mostly find advice on rotted wood. That’s carpentry. The sill outside a brick or stone house is usually masonry, and it fails differently: it cracks, flakes, tips back or lets go at the joints.
Here’s how to tell what you’ve got:
- Precast concrete: smooth, uniform grey concrete, cast in a mould and set in one piece.
- Poured concrete: formed in place, often rougher, and often patched a few times over the years.
- Natural stone: limestone or sandstone with visible grain or bedding lines, common on century homes.
- Brick: a row of bricks set on edge, called a rowlock, and tipped to shed water.
If your sill is wood and soft under a screwdriver, you want a carpenter or window installer. If it’s any of the above, it’s our work, and it ties into the same masonry repair and repointing we do on the wall around it.
Signs Your Window Sill Needs Repair
Sills fail slowly, and the damage often shows up on the wall below before you notice the sill itself.
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Cracks across the sillA crack straight through lets water into the wall below.
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Flaking or spallingThe surface coming off in chips or layers.
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Sill tipped backWater pools or runs toward the window instead of off the front.
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Open joints at the endsGaps where the sill meets the brick or stone.
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Stains below the windowStreaks or white residue on the wall under the sill.
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Water insideDamp drywall or peeling paint under the window can start at the sill.
How We Repair or Replace a Window Sill
Here’s what a sill job with us looks like, start to finish.
1. Inspect the Sill
We check the sill, its slope, the joints around it and the brick below, and tell you plainly whether it can be saved.
2. Clear Written Quote
Itemized and in writing, so you can weigh a repair against a new sill before deciding.
3. Repair or Replace
We patch and seal a sound sill, or cut out a failed one, set the new sill on a full mortar bed with the right slope and rebuild the brick at its ends.
4. Repoint & Walkthrough
Joints around the sill get repointed, the site gets cleaned up, and you get a written warranty on the work.
What Window Sill Repair & Replacement Cost
Use these southwestern Ontario ranges to budget, not as a quote. Sill length, material, how high the window sits and how much brick has to come out decide the price, and you’ll get a free written quote per window before any work starts.
Sill Repair
About $300–$800 per sill. Crack sealing, rebuilding chipped areas and repointing on a sill that’s still sound.
Precast Replacement
About $800–$2,500 per window. Old sill out, new precast set, and the brick at the ends rebuilt.
Stone & Upper Floors
Top of that range or more. Custom-cut stone costs more to source and fit, and upper windows need scaffolding.
Window Sills Fixed by Masons
A sill is part of the wall, so at On Point Masonry Repair and Waterproofing we treat it that way: matched materials, the right slope, and the brick and joints around it repaired in the same visit.
- Masonry Sills OnlyConcrete, precast, stone and brick are our everyday work.
- Matched to Your HouseStone, brick and mortar chosen to suit the wall.
- Fully InsuredCovered on every job, ladder or scaffold.
- Written WarrantySill repairs and replacements backed in writing.
- Free, No-Pressure QuotesAn honest assessment, with no obligation.
- 4.9 ★ on Google70+ Google reviews from homeowners across SW Ontario.
Window Sill Repair FAQ
Straight answers about concrete, precast, stone and brick sills.
How much does it cost to replace a concrete window sill?
Plan on about $800–$2,500 per window to replace a cracked sill with new precast concrete around southwestern Ontario. Upper floors, long sills and custom stone push it higher. Quotes are free and itemized per window.
How much does it cost to repair a window sill?
About $300–$800 for a masonry sill that’s still sound. That covers sealing cracks, rebuilding chipped or flaking areas and repointing the joints around it. Wood sill repair is a carpenter’s job, so we don’t price it.
Can I replace a window sill without removing the window?
Yes, for a masonry sill, usually. We cut out the old sill and the brick at its ends, then set the new one and rebuild around it with the window left in place. We’ll tell you up front if the window frame itself is too far gone.
How can I repair a broken window sill on my exterior?
Seal small cracks, but have a broken or tipped sill properly repaired or replaced. A hairline crack in a sound concrete or stone sill can be sealed to keep water out. Broken pieces, deep flaking or a sill that slopes toward the window will keep sending water into the wall below.
Do I need a concrete window sill?
You need a sill that sheds water, and on a brick or stone house that’s usually concrete, precast or stone. Without one, rain runs down the face of the wall and soaks the joints under the window. A replacement should match the house as closely as practical.
Do you repair wooden window sills?
No. Wood sills are carpentry or window work, and we stick to masonry: concrete, precast, stone and brick. If your sill is wood and rotting, a carpenter or window installer is the right call.
What Homeowners Say About Our Sill & Brick Work
4.9 ★ on Google from 70+ Google reviews. A few from homeowners who had sills and brick repaired.
Dave and John were very friendly. They did a great and professional job on our brick windowsill replacement, and the reparation of a crack in our foundation wall.
Many thanks to Dave and his team. The job was definitely challenging and hand digging around the foundation was required. Then a sill had to be replaced and some brickwork also was needed. … The job they did could not have been done any better by anyone.
We had some exterior cracks in different spots (chimney area, above doors, window sills, below windows, and some general holes and cracks). They filled and repointed many of these issues. … Good communication, friendly, and would definitely call again for any additional work in the future.
Window Sill Repair Service Areas
Based in Paris, Ontario, we repair and replace masonry window sills across SW Ontario:
Request Your Free Window Sill Quote
Tell us how many windows, which floor they’re on and what the sills are made of if you know, and send a photo of each if you can. We’ll reply with what we think each sill needs. Rather talk it through? Call (519) 802-2138 or email [email protected].
Cracked window sills? Let’s fix them before the wall pays for it.
Concrete, precast, stone and brick sills repaired or replaced across SW Ontario, with a written warranty.
Call (519) 802-2138