Rotted Sill & Sash Restoration — 1920s Home, Crystal Lake

The problem

The homeowner noticed peeling paint and a soft spot on the sills of two south-facing windows in the front room. A replacement company had quoted two new windows, plus new interior trim, and said the originals were "too far gone."

What we found

Once we opened the paint up, the rot was limited to the outer half of both sills and the bottom rail of one sash. The rest of the frames and both upper sashes were solid old-growth wood — far better material than most new windows are made from. The cause was simple: the sills had lost their slope over the years, so snowmelt sat on them all winter.

What we did

• Cut the rotted wood back to sound timber on both sills and the lower sash rail.
• Treated the surrounding wood with a consolidant to harden it.
• Milled matching replacement pieces and spliced them in, reshaped to the original profile.
• Restored the sill slope so water drains away from the house.
• Primed, caulked and painted to match the rest of the trim.

The result

Both original windows were kept, with their original glass, hardware and interior trim untouched. The repair took one day on site, and the rebuilt wood is covered by our 3-year warranty.

What this kind of repair costs

Localized sill and sash rot repair typically runs $200–$700 per window, depending on how far the rot has spread. Replacing a wood window of this size typically costs $800–$2,500+ installed. See our rotted wood repair and sill repair pages for details.