Rotten Window Frame Repair in Boston

Frame rot is serious. But it's not always game over.

The window frame is the structural box that holds everything together — the jambs (sides), the head (top), and the sill (bottom). When rot reaches the frame, most contractors recommend full window replacement because the frame is what attaches the window to the wall. We disagree. With proper repair techniques, even significantly rotted frames can be saved.

How frame rot starts

Frame rot usually starts at the sill (which collects water) and spreads upward into the side jambs. Water can also enter from above if the head casing or flashing fails. Once rot reaches the frame, structural integrity is compromised — windows may stick, racking, or even pull away from the wall.

Signs of frame rot

• Soft or spongy wood in the jambs or head

• Visible gaps between the frame and the surrounding wall

• Window sash that doesn't sit square in the frame

• Drafts even when the window is closed and locked

• Cracked or peeling paint extending beyond the sill

• Water stains on the interior trim

Our frame repair process

Step 1: Source identification

Before any repair, we identify why the frame is rotting — usually a flashing failure, missing caulk, or a damaged sill. If we don't fix the source, the rot will return.

Step 2: Damage assessment

We probe the frame to map the full extent of rot — visible damage is often only 20–30% of what's actually there. This gives us an accurate scope.

Step 3: Repair methods

Depending on damage, we use a combination of:

• Wood splicing — replacing rotten sections with new solid wood

• Epoxy reinforcement — for areas where structural strength is needed but wood is partially damaged

• Section replacement — replacing entire jambs or head pieces when too far gone

Step 4: Weatherproofing

We address the original cause of the rot — install proper flashing, caulk seams, and seal the frame against future water intrusion.

When frame replacement makes sense

If more than 60% of the frame is severely rotted, or if the rough opening itself has structural damage, full window replacement may be the better option. We'll always tell you honestly when repair isn't the right call — no upselling.

Get a free assessment

Frame rot only gets worse with time — and more expensive to fix. Call (617) 982-1211 for a free on-site evaluation in Boston, Brookline, Newton, and surrounding towns.