How much does window sill replacement cost?
How much does window sill replacement cost?
$250 – $800 average cost per sill (3 to 8 linear feet)
Average window sill replacement cost
Interior or exterior window sill replacement costs $250 to $800 per sill for an average-sized window sill between 3 to 8 feet long. Replacing the sills protects your windows and prevents water damage. The total cost of replacing window sills depends on the sill material, window size, labor rates, and location.
| Sill length (linear feet) | Average replacement cost |
|---|---|
| 2 | $200 – $250 |
| 3 | $250 – $300 |
| 4 | $300 – $400 |
| 5 | $400 – $500 |
| 6 | $500 – $600 |
| 8 | $600 – $800 |
| 10 | $800 – $1,000 |
Cost of replacing window sills by material
The cost of window sill materials varies based on the durability, aesthetics, and installation complexity. Non-porous materials like aluminum, composite, and tile are durable and low maintenance. Stone, tile, and hardwood sills are often the costliest options.
| Window sill material | Average cost per linear foot (materials only)* |
|---|---|
| Aluminum | $8 – $20 |
| Composite | $10 – $25 |
| Fiberglass | $8 – $20 |
| Stone | $20 – $80 |
| Tile | $10 – $45 |
| Vinyl | $5 – $20 |
| Wood | $7 – $40 |
*Cost does not include installation labor.
Aluminum
Aluminum window sills cost $8 to $20 per linear foot for materials alone. They resist weather brilliantly, preventing moisture damage with corrosion-resistant material. Aluminum offers a sleek, modern look and adapts to various architectural styles with many color options. They provide lightweight, long-lasting protection and energy efficiency for buildings.
Composite
Composite window sill materials cost $10 to $25 per linear foot. These sills combine durability and low maintenance by blending wood fibers and plastic polymers. Their resistance to rot, decay, and moisture makes them ideal for weather-exposed areas. Composites also come in a variety of finishes that mimic wood grain without the upkeep of traditional wood.
Fiberglass
Fiberglass window sills cost $8 to $20 per linear foot. Fiberglass offers exceptional strength and durability, resisting warping, cracking, and moisture damage over time. It is lightweight, easy to install, and requires minimal maintenance. These sills perform well in harsh weather, providing a long-lasting, stable surface that withstands the elements.
Stone
Stone window sills cost $20 to $80 per linear foot. Stone offers natural durability and a timeless aesthetic, resisting wear from weather and sunlight. Popular stone types include granite and marble, which provide strong, elegant, and low-maintenance surfaces.
Tile
Tile window sills cost $10 to $45 per linear foot. Tile offers a decorative, customizable look with many colors and patterns. It is resistant to water and easy to clean, but grout may need occasional resealing. Tile sills can complement both interior and exterior designs, combining aesthetics with moisture protection.
Vinyl
Vinyl window sills cost $5 to $20 per linear foot, making them an affordable option. Vinyl resists moisture, rotting, and insect damage. Its lightweight, low-maintenance properties simplify installation and upkeep. Vinyl sills come in limited colors and may not offer the same durability or aesthetic appeal as premium materials but provide good value for budget-conscious projects.
Wood
Wood window sills range from $7 to $40 per linear foot. Wood offers a classic, warm aesthetic and can be finished in various stains or paints. While attractive, wood requires regular maintenance to prevent moisture damage, warping, or decay. Different species offer varying durability levels, and proper sealing extends lifespan but involves more upkeep than synthetic options.
Window sill installation cost factors
Various factors influence the total cost of window sill replacement.
Number of windows: Replacing multiple sills during the same project can lower the cost per window, thanks to split-trip fees and bulk discounts.
Window size: Replacing a wider or deeper sill drives up both material and labor expenses since it requires more cutting, finishing, and support.
Labor rates and complexity: Professional labor often makes up 80% to 90% of replacement costs, especially for large or intricate projects with tight spaces.
Location of window: Upper-story or hard-to-access windows require safety equipment and more labor, increasing the price.
Type of window: Specialty windows, such as bay, bow, or picture windows, require more material and custom fitting, increasing overall cost.
Window sill repair cost
Window sill repair costs $150 to $350 on average to fill in scratches or remove damaged parts and partially replace the sill. Repairing cosmetic sill damage can be less expensive than a full replacement, especially when the structural integrity remains sound.
If your window sill has evidence of wood rot, water damage, or pests, call a professional. Some types of damage may get worse or spread to your siding if you try to fill or paint over it.
Related window projects
If your windows are damaged or need a repair or replacement, you may be able to save money by bundling projects. The table below shows the cost of common window repair jobs:
| Project | Average cost per window |
|---|---|
| Window frame repair cost | $150 – $600 |
| Window repair cost | $175 – $600 |
| Window screen replacement cost | $100 – $350 |
| Window replacement cost | $450 – $1,500 |
When to replace a window sill
Your window sill plays a vital role in protecting your home from water damage and supporting your window. Over time, exposure to the elements can weaken or damage the sill, reducing its effectiveness and potentially leading to costly repairs.
Look out for these signs that your window sill may need replacing:
Soft or spongy wood: Press the surface with your finger or a screwdriver. If it feels soft or gives way, rot has compromised the sill’s integrity.
Visible rot or discoloration: Dark stains, black spots, or greenish mold indicate moisture damage and fungal growth.
Peeling paint or bubbling finish: These are signs that moisture is trapped beneath the surface, leading to deterioration.
Cracks or holes: Pros can sometimes repair small surface cracks, but deep cracks or holes usually mean replacement is necessary.
Mold or mildew smells near the window: This odor often suggests moisture intrusion behind the sill or wall.
Window sits unevenly or doesn’t close properly: A deteriorating sill can cause the window frame to shift or sag, affecting operation.
Water pooling or damage near the sill: Moisture accumulation or water stains indicate poor drainage or sealing.
Acting promptly to replace a damaged window sill prevents larger problems like water intrusion, mold growth, and structural damage, preserving your home’s value and comfort.
Window sill installation FAQs
What is a window sill?
A window sill is the horizontal piece forming the base of a window opening, supporting the window frame, and keeping water away from the wall to prevent moisture intrusion. It also provides a decorative element or a space for plants and other items.
Do new windows come with new window sills?
Most new replacement windows do not include a sill. The existing window sill remains, so homeowners should consider replacing or repairing the sill when installing new windows for best protection and appearance.
Who replaces window sills?
Window installation specialists, general contractors, or skilled carpenters can replace or repair window sills. Homeowners should hire a professional for this project due to the specialized cutting, sealing, and water management required.
How long does it take to replace a window sill?
A professional can replace a standard window sill in 1 to 2 hours. Larger or more complex installations, such as for bay or bow windows, may require four to five hours due to intricate finishing work.
Can you sit on a window sill?
Standard window sills are not meant to support full body weight, and you may damage or compromise their structural integrity if you sit on them. Deeply built or custom sills may offer additional strength, but sitting on them is still not recommended.
Getting estimates from window repair companies
Follow these tips to get accurate, reliable estimates from window repair companies near you:
Contact several reputable contractors to compare labor and material pricing.
Insist on detailed, written quotes showing labor, materials, and any additional fees.
Research local companies with positive reviews on HomeGuide and Google.
Clarify the sill type, material, and location to receive realistic, apples-to-apples bids.
Ask for and verify recent client references to gauge quality and reliability.
Questions to ask a window technician
Before committing to a specific contractor, ask the right questions to avoid costly surprises:
What is included in your quote?
Does the price cover labor, materials, clean-up, and any disposal fees?
Who will do the actual work on my windows?
Do you use trained, insured, and background-checked professionals?
Can you match the material and color of the existing window sill?
Will you have to order any parts? If so, how long will that take?
How will you address water management?
Which installation methods protect against leaks and future rot?
What is the expected timeline?
Do you offer warranties?
What support can you offer for any future repairs?
Using our proprietary cost database, in-depth research, and collaboration with industry experts, we deliver accurate, up-to-date pricing and insights you can trust, every time.