Replacing a rotted window sill typically costs $150-$700 per window, with a national midrange near $400 for a straightforward repair. The final price depends on sill material and size, labor, access, and whether rot has spread into the jamb, framing, or surrounding trim.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Sill replacement | $150 | $400 | $700 | One window, sill only |
| Wood sill material | $20 | $60 | $150 | Per sill; species and size vary |
| Labor | $100 | $275 | $600 | Typically 2-5 hours |
| Rot and framing repair | $100 | $350 | $1,200 | Additional work if damage extends beyond sill |
What a Typical Window Sill Replacement Costs
A contractor may charge $150-$350 to replace a small, accessible sill with standard wood, or $350-$700 for a larger exterior sill, custom cutting, and paint-ready trim. These prices generally cover removing the damaged board, fitting a replacement, fastening and sealing it, and basic cleanup. Painting or staining may be included, but it should be confirmed in the estimate.
For a typical 3- to 5-foot sill, materials often cost $20-$150; labor and setup account for most of the bill. Composite or PVC sills may cost more than basic pine but resist moisture better. Assumptions: one standard residential window, normal access, no major framing damage, and midrange U.S. labor rates. Budget about $300-$500 for a routine sill-only repair.
How Removal, Materials, and Labor Shape the Quote
Quotes differ in what they include. Ask whether the price covers exterior caulk, interior trim, primer or paint, debris removal, and repairs to concealed wood. A low bid may cover only the visible board, while a more complete scope may include sealing and finishing.
| Quote item | Typical price | What changes the charge |
|---|---|---|
| Removal and disposal | $30-$100 | Fasteners, paint layers, and careful trim removal |
| Replacement sill | $20-$150 per sill | Length, depth, wood species, or PVC/composite |
| Labor and fitting | $75-$125 per hour | Cutting, leveling, fastening, and sealing time |
| Paint or stain | $40-$150 | Surface preparation, coats, and color matching |
| Rot repair | $100-$1,200 | Extent of damage to jamb, sheathing, or framing |
Confirm whether labor is billed hourly or included as a fixed job price.
Why Sill Length, Material, and Hidden Rot Matter
Length and profile affect both material use and cutting time. A simple sill under 4 feet is usually cheaper than a wide or unusually shaped sill over 6 feet, especially if matching a historic profile requires custom milling. Hardwood, PVC, and composite options can add roughly $30-$150 per opening over basic pine, depending on dimensions and finish.
Hidden damage is the largest cost risk. If rot is confined to the sill, replacement may stay within the standard range. Damage extending more than 6 inches into a jamb or into the framing can add $200-$800 or more; extensive structural repair may exceed $1,200. Upper-story access, tight work areas, and fragile surrounding trim also raise labor time. Ask the contractor to document concealed damage before approving extra work.
How Many Labor Hours Does One Sill Take
A straightforward replacement generally takes 2-5 hours for one experienced carpenter, including removal, fitting, sealing, and cleanup. Difficult trim removal or custom shaping can extend the visit to 6-8 hours. A carpenter commonly charges $75-$125 per hour, while some contractors set a minimum service charge of $150-$300 for a small repair.
Several sills completed in one visit may reduce the average cost per opening because setup and travel are shared. However, each window still requires inspection, fitting, and sealing. For multiple windows, request both a per-sill price and a combined project price.
Repair Add-Ons That Can Raise the Final Bill
Painting, caulking, and replacing adjacent trim may add $40-$250 per window, depending on preparation and finish. A moisture inspection or small diagnostic visit may cost $75-$200, though some contractors waive it when hired for the repair. Lead-safe work on older painted trim can add $100-$500 or more because containment and cleanup require additional labor.
Exterior water entry should be corrected along with the sill. Failed caulk, damaged flashing, or a leaking gutter can cause new rot and may add $100-$500 for targeted fixes. Replacing a window is not normally needed for sill rot alone, but a damaged frame or sash may change the scope substantially. Get separate line items for the sill, adjacent wood, finish work, and water-control repairs.
Three Window Sill Quotes at Different Scopes
A 3-foot pine sill on the first floor might take 2.5 labor hours at $90 per hour, with $45 in materials and $35 for removal and finishing. The estimated total is about $305. A 5-foot PVC sill with paint-ready trim could take 4 hours at $105 per hour, plus $120 in materials and $90 for disposal and finishing, totaling about $630.
A 4-foot sill with rot extending into the jamb may require 6 labor hours at $110 per hour, $90 in materials, and $350 for framing repair and finish work, for a total near $1,100. These examples show why the extent of hidden damage matters more than the board price.
When Wood Filler Costs Less Than Full Replacement
For a small, shallow area of damage, epoxy or wood filler may cost $100-$300 when handled by a professional. It is a temporary or localized repair option when the remaining sill is solid and the moisture source has been fixed. It is generally unsuitable when rot is soft, widespread, or affecting the sill’s support and seal.
Replacing the sill usually costs more upfront but restores the full damaged piece and allows inspection beneath it. To keep the bill controlled, ask whether a repair is structurally sound, choose a standard-size material where possible, and handle simple nearby cleanup or furniture moving before the crew arrives. Compare at least two written quotes with matching scope, material, finish, and rot-repair allowances. Do not compare a filler patch with a full replacement as if they provide the same repair.
How to Keep the Replacement Price Under Control
Request a written estimate that states sill dimensions, material, removal, sealing, paint or stain, disposal, and the hourly rate or fixed labor charge. Ask the contractor to contact the homeowner before work exceeds a stated allowance for hidden rot. This reduces the chance of an unexpected change order after trim is removed.
Replacing several damaged sills together can reduce repeated setup charges, but sound sills do not need replacement solely to qualify for a bundle. Standard pine is often the lowest-cost choice; PVC or composite may be worth comparing where exposure to moisture is persistent. Fix the source of water intrusion before installing a new sill to avoid paying for the same repair twice.