Old wood windows: repair, restore or replace?

If your old wood windows have sound frames and sashes, repairing them usually costs a few hundred dollars per window, and full restoration often $500 to $1,200, which is close to the price of a good new wood window. If the frames are rotted, the sashes are falling apart or the house is not historic, replacement is usually the better value. The honest answer depends on the window, not on a general rule, so this guide explains how to tell.

Lower Merion TwpDec 2025

The numbers

These ranges come from 2026 cost guides and restoration surveys, which vary a lot.

Restoration labor commonly runs $60 to $180 per hour nationally, and lead-safe work adds cost on pre-1978 windows.

Questions to ask about each window

Walk every window and answer these:

1. Is the frame sound? Push a screwdriver into the sill, the bottom of the jambs and the outside sill. Small soft spots can be repaired. Large rot means replacement.
2. Is the sash sound? Check the bottom rail of each sash, where water sits. Loose joints can be reglued. Rotted rails can be patched or replaced.
3. Does it move? Paint-stuck sashes are common and fixable. Broken sash cords and missing weights are cheap to fix.
4. Is the glass old and wavy? Old glass is part of what makes historic windows worth keeping.
5. Is it drafty? Most drafts come from worn weatherstripping and gaps, which can be fixed without replacing the window.
6. Does the house's character depend on it? On a stone farmhouse or a historic district house, original windows matter more than on a 1960s ranch.

When repair or restoration makes sense

• The frames and most sashes are sound.
• The house is historic or in a historic district, where original windows have value and replacements may need review.
• You like the look of old glass and true divided lites.
• A good storm window can solve the energy problem.

A restored wood window with a good storm window can perform close to a new double-pane window and last decades more.

When replacement makes sense

• The frames or sills are rotted through.
• Most sashes are failing, not just one or two.
• The windows were replaced once already with poor units.
• The house is not historic and you want low maintenance.
• The windows do not meet egress for a bedroom.

On the Lower Merion stone house, new Andersen windows were set into the old fieldstone walls on new wood sills, as part of a full renovation where the walls and trim were being rebuilt anyway.

What restoration involves

1. Remove the sashes and label them.
2. Strip loose paint, using lead-safe methods on pre-1978 windows.
3. Repair rot with epoxy or wood dutchmen, and reglue loose joints.
4. Reglaze with new putty, replacing broken glass.
5. Prime and paint, including the glazing.
6. Replace sash cords and balance the weights, or install new balances.
7. Repair and paint the frame and sill.
8. Add weatherstripping at the meeting rail and the sides.
9. Rehang the sashes so they slide and lock.

It is slow, careful work, which is why it costs what it does.

Storm windows

A storm window adds a second layer of glass and stops drafts. It protects the old window from weather and can make an old window nearly as efficient as a new double-pane one.

• Exterior storms protect the wood and are the traditional choice. Low-profile models look much better than the old aluminum triple-tracks.
• Interior storms are invisible from outside, which suits historic houses, and are easy to remove in summer.

Replacement options that respect older houses

If you replace, choose windows that suit the house:

• Wood or wood-clad windows with simulated divided lites, matching the original grille pattern.
• Full-frame replacement where the original frame is rotted, so the new window fills the opening and does not shrink the glass.
• Matching interior casing and stools, or reusing the originals where possible.
• Narrow sightlines, so the window does not look heavier than the original.

Marvin and Andersen both make lines suited to older houses. Our Marvin versus Andersen guide compares them. We have installed both on jobs in Lower Merion.

Lower Merion TwpApr 2026

Lead paint

Almost every old wood window has lead paint. Scraping, sanding or removing old windows disturbs it. EPA rules require a certified lead-safe firm for renovation and window work on pre-1978 houses, with containment, dust control and cleanup. Whether you repair or replace, ask about it.

Mixing approaches

You do not have to choose one answer for the whole house. A common plan:

• Restore the street-facing windows that give the house its character.
• Replace the worst windows, often on the weather side or in a kitchen or bathroom.
• Add storms to the restored windows.

That keeps the look where it matters and solves the problem windows.

Energy, honestly

Single-pane old windows lose more heat than new double-pane windows. But a lot of a window's heat loss is air leakage, which weatherstripping and storms fix. Replacement windows take many years to pay back in energy alone. Comfort, condition and maintenance are better reasons to decide.

Contracts and permits in Pennsylvania

Repairing or restoring windows does not need a building permit. Replacing windows in the same openings usually does not either. Historic districts may require review before you replace windows on street-facing walls. Contracts over $500 must be in writing in Pennsylvania, with three business days to cancel.

Signs a window is worth saving

Some old windows are worth more effort than others. Good candidates for restoration usually have:

• Old-growth wood, dense and heavy, which is much more rot-resistant than most modern wood.
• Original wavy glass that you want to keep.
• True divided lites, with individual panes held by wood muntins.
• Sash weights and pulleys in working or fixable order.
• Frames and sills that are mostly sound, with only small patches of rot.

Windows that are poor candidates usually have rotted frames, sashes with broken joints in several places, many replacement panes of modern glass already, or a history of being painted shut on the outside.

Working with a historic commission

If your house is in a historic district, such as parts of Lancaster city or West Chester borough, exterior window changes on visible walls often need approval. Commissions usually prefer repair, then replacement in kind with wood windows that match the original profile and lite pattern. A clear written description of the window condition, with photos, helps the application. We can provide that from our inspection.

Upkeep that keeps old windows working

A restored window needs a little care to stay that way:

• Repaint the exterior every five to eight years, and touch up glazing putty when it cracks.
• Keep the sills painted, including the end grain at the corners.
• Check sash cords and replace any that fray before they break.
• Clean and lightly wax the sash channels so the windows slide.
• Keep storm windows on in winter, and open their weep holes so water can drain.
• Look at the bottom rails of the sashes each spring, where water sits.

With that care, a restored window can outlast several generations of replacement windows.

A note on cost comparisons

When you compare a restoration quote to a replacement quote, compare the whole job. Replacement prices often leave out new interior trim, exterior trim, lead-safe work and disposal, while restoration prices usually include paint. Ask both for the same scope.

Questions people ask about old wood windows

Are old wood windows worth saving? Often, yes, if the frames and sashes are sound and the house is older or historic. They can last another 50 years with care.

How long does restoring a window take? A single window can take a carpenter most of a day or more, spread over several days for drying and paint.

Can old windows be made energy efficient? Weatherstripping and a good storm window make a big difference, and many owners are surprised how comfortable restored windows are.

Can you repair just the sash? Yes. Sashes are removable and can be repaired or replaced on their own while the frame stays.

Is the estimate free? Yes. We check each window and tell you which ones are worth repairing and which need replacement.

See our window replacement service, the Andersen windows in the Lower Merion stone house and our rotted window sill guide.

Ask us to look at your windows