Evansville Tuckpointing Cracked or sinking limestone sill: what it costs and what it damages next
A limestone sill that is cracked through, spalling on its top face, tipping back toward the house, or dropping at one end has stopped doing its only job, which is throwing water clear of the wall below the window. Repair or reset runs $300 to $1,200 per sill. It is worth doing early, because everything a failed sill damages next, the brick under the opening and the joints around it, costs more than the sill.
Check this first (ten minutes, a level and a dollar bill)
- Check the slope. Set a small level on the sill. It should fall away from the window. Flat or falling back toward the house means water is running into the wall.
- Look under the front edge. There should be a drip: a groove or a projecting nose that makes water let go instead of curling back to the brick. If someone has caulked or parged the underside flat, the drip is gone.
- Find the crack line. A crack straight across the middle of a sill usually means movement below or a lintel above. A crack along a joint at one end usually means the sill has shifted.
- Feel the top face. Sugary, powdery stone that rubs off on your hand is weathered limestone, and it means water has been sitting on it.
- Look below the window. Spalled or stained brick, missing joints, or efflorescence under the sill confirms the sill has been feeding the wall.
- Look above the window too. If the head of the opening shows step cracks, the lintel may be pushing everything around, sill included.
What is usually wrong
| What you are seeing | Likely cause | Fix and cost |
|---|---|---|
| Tight crack, sill still sloping correctly | Thermal and freeze-thaw stress | Pin and patch, $300 to $1,200 |
| Sill flat or tipping back toward the house | Settled bedding or a badly reset sill | Reset the sill, $300 to $1,200 |
| Drip edge caulked or parged over | A previous repair that removed the drip | Restore drip and repoint, $300 to $1,200 |
| Sugary, eroding top surface | Weathered Salem limestone plus standing water | Consolidate or replace, $15 to $40 per sq ft of stone |
| Sill broken in two with one half dropped | Movement below or a failed lintel above | Reset or replace, plus lintel $400 to $1,500 |
| Spalled brick under the sill | Water running back into the wall for years | Sill work plus units at $20 to $40 each |
| Cracked sill on a chimney or a cap stone | Exposure on all faces | Stone repair, $15 to $40 per sq ft |
Ranges are published on the pricing page, and stone and limestone repair explains how a match is sourced and how a Dutchman repair works.
Why Evansville has so much limestone to fix
Look at any brick house here from the 1880s through the 1950s and the sills, caps, water tables, and door surrounds are Indiana limestone, because the quarries are up the road. Indiana limestone is Salem Limestone, a Mississippian marine deposit quarried between Bloomington and Bedford since the first quarry opened in 1827, and by 1929 Indiana quarries were producing 12,000,000 cubic feet of usable stone a year. It went into the Empire State Building, the Pentagon, and roughly 35 of the 50 state capitols, and it went into a very large share of the sills in Bayard Park, Riverside, Lincolnshire, and the East Side.
It is also calcium carbonate, which acid rain wears relatively quickly, and it is porous enough to hold water going into a freeze. Evansville runs it through roughly 77 freeze-thaw cycles a winter, from 92.6 nights a year at or below 32 degrees against only 15.5 days that never thaw, under 45.31 inches of annual rain. A sill is the most exposed horizontal surface on the wall, so it takes that punishment first. The Indiana limestone and Ohio Valley brick page goes further into what the material is and how it should be treated.
When it is structural, not cosmetic
A cracked sill is not usually holding the building up, but it is a warning light. Treat it as structural when the sill has dropped, when the brick above the window has cracked or sagged at the same time, when the crack keeps opening season to season, or when a lintel below or above the opening is involved. Those cases get the opening addressed as one repair rather than a stone patch, and the lintel and sill replacement page covers that work.
What to expect on the call
Photograph the whole window, the sill from the side so the slope shows, the underside of the front edge, and the brick below. A level laid on the sill in the photo tells a mason more than a paragraph. Expect an honest split between pin and patch and full reset, and expect the water path to be named. If your house is in a preservation area, replacing a visible stone element is more likely to need review than repointing, so read the historic district masonry rules before you schedule anything.
Frequently Asked Questions
What does it cost to fix a limestone sill in Evansville?
Limestone sill repair or reset runs $300 to $1,200 each. Pinning and patching a cracked sill that still sits true is the low end. Cutting out a sill that has lost its slope, dropped, or broken through, sourcing a match, and resetting it with the brick above shored is the high end. Broader stone work is priced at $15 to $40 per square foot.
Why do limestone sills crack in the first place?
Three reasons stack up here. Indiana limestone is calcium carbonate and is worn by acid rain and freeze-thaw. A sill sheds all the water off a window, so it stays wet longer than the wall. And a sill is usually bedded on mortar over an opening, so any movement in the lintel or settlement below shows up as a crack in the stone first.
Can a cracked sill just be caulked?
Caulk over a cracked sill traps water inside the stone and inside the wall below it, which is the opposite of what a sill is for. A tight crack in a sound sill can be pinned and patched with a matched repair mortar so it still sheds water. A sill that has lost its slope or its drip needs to come out.
What happens if I leave a broken sill alone?
Water stops running off the sill and starts running into the wall under the window. Then you get spalled brick below the opening, efflorescence inside, and eventually loose units. A $300 to $1,200 sill left alone for a few winters usually adds brick replacement at $20 to $40 per unit and a repoint of the wall under it.