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Open 7 days · 8am–8pm | Fully insured
Call or text(224) 209-0862
★★★★★ 4.9· 145+ reviews· 20-yr glass warranty
Frames, jambs & mullions · 40+ nearby towns

Window Frame & Jamb Repair. Rotted, Warped or Out of Square.

Rotted jambs and frame corners, rotted mullions between windows, frames that warped or shifted — we rebuild and re-square the frame so the window works again, without replacing it.

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  • All window types & brands
  • Fully insured
  • Price match
Can it be fixed?Usually — rot rebuilt, frame re-squared
Typical price$50 – $500per window · confirmed before work starts
How longUsually one visit
Peace of mind3-year wood repair warranty
The Problem

Rotted, Warped or Shifted: What Happens to Window Frames

The frame is the backbone of your window. When it warps, cracks, or racks out of square, everything that depends on it fails too — the sash sticks, the seal gaps, and the lock stops lining up.

A window frame holds the sash in a precise, square opening. Over years, that squareness gets lost.

House settling shifts the rough opening and twists the frame; moisture makes wood swell, cup, and warp; a poor original installation that was never shimmed level surfaces as sticking and gaps down the line; and decades of paint buildup, hardware stress, and thermal movement all add up.

The frame ends up out of square — even when the glass and sash themselves are fine.

The good news is that a frame problem is a geometry-and-structure problem, and geometry can be restored. Rather than tearing out a whole window because it sticks or leaks, we bring the frame back to square, reinforce and repair the damaged areas, and re-establish the seal and lock alignment.

Frame repair vs. rotted wood

Frame repair addresses structure and geometry — warping, racking, cracks, and loose joints. That's different from rotted wood repair, which addresses decay — wood gone soft from moisture. The two often appear together, and we handle both; during assessment we identify which is driving your window's problem so the repair fixes the true cause.

Most frame repairs start with rot: the bottom of the side jambs, the lower frame corners, and the mullions between joined windows are where water collects.

The rest are frames that warped, cracked or were pulled out of square as the house settled. Either way the symptoms look alike — the window sticks, won't lock or lets in drafts — and the fix is to rebuild or re-square the frame, not replace the window.

Not sure this is your problem? Use our window triage guide — pick the symptom and see the likely cause and cost. Related reading: Rotted wood repair · Basement window repair

Soft wood at the jamb bottoms

Rot where the side jambs meet the sill.

Gaps or cracks at the corners

Frame joints opening up and letting water in.

Rotted mullion between windows

The post joining two windows going soft.

Sticks or binds in one corner

A warped or out-of-square frame.

Drafts or daylight at the edges

The frame no longer seals against the sash.

Rotted window frame and sash wood on an upper-floor window
Recognize this? It's a common, repairable problem.
Is your window frame out of square?
Square frameOut of squareA = BA ≠ B12345
  1. Measure corner to corner — with a tape measure, across both diagonals of the frame opening.
  2. Equal diagonals — the frame is square.
  3. Different diagonals — a difference of more than about 1/4 inch usually means the frame has shifted.
  4. Binding corner — where the sash rubs or sticks.
  5. Opposite corner — often the gap where drafts and water get in.

An out-of-square frame explains most sticking, drafty windows — and it can usually be corrected.

The Fix

How We Repair a Window Frame

Diagnose the Cause

We check the frame for square, identify what moved it — settling, moisture, or install — and confirm whether rot is also involved.

Re-Square & Shim

The frame is brought back to level and plumb and properly shimmed, so the opening is square and the sash has room to move.

Repair & Reinforce

Cracked jambs, split corners, and weakened joints are repaired and reinforced so the frame holds its shape for the long term.

Reseal & Test

We re-establish the weatherseal and lock alignment, then test that the window opens, closes, seals, and locks smoothly.

BeforeRotted arched window frame and trim before repair
AfterArched window frame rebuilt and painted after repair
Rot in Frames

Rotted Jambs, Frame Corners & Mullions

Frames rot from the bottom up. Water runs down the window, sits where the frame meets the sill, and soaks into the end grain.

Jamb bottoms — the lower ends of the side jambs — soften first, often behind paint that still looks fine. Frame corners open up where joints stop shedding water.

And where two or more windows are joined, the mullion between them collects water from both sides and rots from the inside out — especially in bay and bow windows. On clad windows, the wood frame can rot under the aluminum or vinyl cladding with little to see from outside.

We cut the rot back to solid wood, treat what's left, splice in matched wood shaped to the frame's profile, and seal it so water sheds again. The window stays in place. For rot in other parts, see sill repair, rotted sash repair, brick mold repair or bay window repair.

Repair vs. Replace

Window Frame Repair Cost

Replacing the window$800 – $2,500+
Repairing itFrom $50

Typical prices

Per window · typical local prices
Alignment & sticking windows$50 – $500
Frame or jamb wood repair (typical)$200 – $700
Sash repair if the frame damaged it$400 – $700
Why the final price can differ: these are typical ranges, not quotes. What moves the price: the size and type of glass (tempered, low-E, triple-pane, decorative), how far rot has spread once the wood is opened up, second-story or ladder access, parts availability on discontinued brands, and how many windows are done in the same visit — multi-window jobs cost less per window. Minimum service visit: $150. We confirm and agree the price with you before starting. Compare all repair prices →

A frame that's out of square is exactly the kind of problem a replacement company uses to justify a whole new window. But re-squaring, reinforcing, and repairing an existing frame costs a fraction of replacement — and keeps a window that, on most older homes, is built better than what would replace it.

Frames on older McHenry County homes were frequently made from dense, old-growth wood that outlasts modern materials, and repairing the frame preserves both that quality and the home's original proportions and character.

Cost depends on how far the frame has moved and whether repair, reinforcement, or partial rebuilding is needed — we give you an estimate after a free assessment so you can weigh the real number before deciding. In the large majority of cases, frame repair is both the cheaper and the better choice.

Why frames shift in McHenry County homes

Clay-heavy soils across the county expand when wet and shrink in dry summers, so houses settle slowly for decades — and window frames follow. Freeze-thaw cycles pry at every joint, and frames on the lake- and river-facing sides of homes in Crystal Lake, Algonquin and Fox River Grove take the most moisture.

DIY or Pro?

Sticking or Drafty Frame: What You Can Check

Safe to do yourself

  • Clean and lightly wax the sash tracks — dirt alone can make a window bind.
  • Check for gaps by closing the window on a strip of paper: if it slides out easily, the seal is not closing.
  • Re-caulk small interior gaps where the trim meets the wall.
  • Note which corner binds or leaks — it tells us which way the frame has moved.

Call a pro

  • Planing or sanding a sticking sash — it hides the real problem and can ruin the fit.
  • Forcing a window that binds — frames and glass crack under pressure.
  • Removing interior trim to re-shim the frame — easy to damage plaster and trim.
  • Large cracks through the frame or visibly bowed jambs — that needs structural repair.
Warranty

Warranty on Frame Repairs

3 yearson wood we rebuild or replace — if it rots, we replace it
20 yearsmanufacturer warranty on insulated glass units
Redoif we install hardware incorrectly, we come back and fix it

Parts we don't make (cranks, balances, locks) carry only their supplier's warranty. Leaks from roofs, flashing or siding aren't window defects. Full warranty terms → · Read our reviews

Got a quote to replace these windows?

Send it to us before you sign. We'll tell you — free — whether a repair would solve it for less.

Free Second Opinion
FAQ

Window Frame Repair Questions

Window frames go out of square for a few common reasons. House settling is the biggest one — as a home shifts over the years, the rough opening around the window moves and racks the frame out of square. Moisture is another: repeated wetting and drying makes wood swell, cup, and warp. Original installation problems, like a frame that was never shimmed level and plumb, show up years later as sticking and gaps. And on older homes, decades of paint buildup, hardware stress, and thermal movement all add up. The result is a frame that no longer holds the window square, so the sash sticks, the seal fails, and the lock won't line up.
Most frame problems can be repaired without replacing the window. Depending on the cause, that can mean re-squaring and re-shimming the frame, repairing cracked or split jambs, reinforcing weakened corners, and re-establishing a proper seal so the sash operates and locks correctly again. Full replacement is only necessary when the frame is structurally destroyed throughout — which is far less common than replacement companies suggest. We assess the actual condition and give you an honest repair-or-replace recommendation before any work begins.
Often, yes. When a frame racks out of square or a jamb bows inward, it pinches the sash so the window sticks, binds, or won't close flush. Other causes of a sticking window include paint buildup, swollen wood, or worn hardware and balances — so the first step is diagnosing why it's binding. If the frame has moved out of square, re-squaring and repairing it restores smooth operation. If the issue is the sash or its hardware instead, that's a related repair we also handle. Either way we identify the real cause rather than forcing the window or planing it down as a band-aid.
Usually very much so. Frames on older McHenry County homes were frequently built from dense, old-growth wood that's more durable than the materials in modern replacement windows, and repairing the frame preserves both that quality and the home's original character. Re-squaring, reinforcing, and repairing an existing frame costs a fraction of a full replacement and keeps the window matched to the rest of the house. For historic and character homes especially, frame repair is almost always the better choice over swapping in a stock unit.
They overlap but address different problems. Frame repair is about structure and geometry — a frame that has warped, racked out of square, cracked, or pulled loose so the window no longer operates and seals correctly. Rotted wood repair is about decay — wood that has gone soft and crumbly from moisture and needs to be cut out and rebuilt. A frame can be out of square without any rot, and wood can rot without the frame being out of square, but the two often occur together. We handle both, and during assessment we identify exactly which applies to your window so the repair addresses the true cause.
That's the whole goal of the repair. A frame that's out of square doesn't just look off — it leaves gaps that leak air and water, and it throws off the alignment the lock and weatherstripping depend on. Bringing the frame back to square restores that alignment, so the sash meets the frame evenly, the weatherseal contacts all the way around, and the lock lines up and engages the way it should. The result is a window that operates smoothly, seals against drafts, and locks securely — backed by our warranty.
Yes. Local Window Service repairs window frames throughout 40+ towns within about 40 miles — Lake in the Hills, Crystal Lake, Algonquin, Cary, Huntley, Carpentersville, Elgin and more. Call or text (224) 209-0862.
Alignment and sticking-window fixes typically run $50–$500, and frame or jamb wood repair around $200–$700 per window, depending on the damage. A full replacement window typically costs $800–$2,500+ installed. Our minimum service visit is $150.
Common signs: the window sticks or binds in one corner, the lock no longer lines up, you can see daylight or feel air at the edges, the corners have visible gaps or cracks, or the wood feels soft when pressed with a screwdriver.
Often, yes. Minor warping and out-of-square frames can be corrected by re-shimming and re-fastening the frame. Sections that are badly warped or rotted are cut out and rebuilt with new wood.
Re-squaring and adjusting a frame is usually done in one visit. If sections need to be rebuilt, allow extra time for primer and paint to cure before the final finish.
More Repairs

More Frame & Wood Repairs

Rotted Wood RepairRot cut out and rebuilt with matched wood.Learn more →Sash RepairStuck or loose sashes fixed and rebalanced.Learn more →Leaks & DraftsSeal the gaps a shifted frame leaves behind.Learn more →Hardware & LocksLocks and latches that line up again.Learn more →

Frame & Jamb Repair in these towns and more

Lake in the HillsCrystal LakeAlgonquinCaryHuntleyCarpentersvilleWoodstockMcHenryMarengoJohnsburgIsland LakeLakewoodAll service areas →

Based in Lake in the Hills, serving homes within about 40 miles.

Fix the Frame, Keep the Window.

Call, text, or send a photo. You'll know what's wrong and roughly what it costs — before anyone comes out.

(224) 209-0862Free Quote

★★★★★ 4.9 from 145+ reviews · 20-year glass warranty · Price match