A homeowner with a 1950s house and original wood windows usually asks me the same thing: "They are drafty and the paint is peeling - do I fix them, or throw them out?" The right answer depends on one thing most quotes skip, and that is what the wood looks like when you press a screwdriver into it.
Old wood windows can usually be repaired when the frame and sill are sound and only the paint, glazing putty or weatherstripping have failed; they should be replaced when rot has reached the frame, the sill or the joints, or when you want a sealed double or triple glazed unit instead of the original glass. For a house you plan to keep, a full-frame replacement with new laminated wood windows gives you the same material with a modern sealed glass unit.
The wood systems themselves are on the European wood windows page. This post is about the decision on the old ones.
Should I repair or replace my old wood windows?
Start with the wood, not the glass. Take a screwdriver and press it into the bottom of the sash, the sill and the lower corners of the frame - the places where water sits. Sound wood resists. Rotten wood gives like a damp sponge.
| What you find | What it usually means | Sensible route |
|---|---|---|
| Peeling paint, dry putty, worn weatherstripping, wood firm everywhere | Surface and seal failure only | Repair and repaint; add a storm window if the glass is the issue |
| Soft wood on the sill or lower sash rail only | Local rot | Repair or replace the sash; keep the frame if it is sound |
| Soft wood in the frame, joints opening up, sill that has sunk | Structural decay | Full-frame replacement |
| Windows work but you want better insulation and a quiet room | Original glazing limit | Storm window, or full-frame replacement with sealed glass |
| Windows are sound but the opening is being enlarged or re-planned | New layout | New windows, sized to the new opening |
Old glazing is the reason many people look at replacement at all. The new wood systems I quote are always double or triple glazed, with published U-factors of about 0.14 to 0.15 in their reference configurations (more on those numbers in what a good U-factor looks like). Repairing the wood does not change what the old glass does. Only a new insulating glass unit does.
What are my options for replacing old wood windows?
There are four, and they are not interchangeable:
- Repair what you have. Best for sound wood on a house with real character. Cheapest in materials, slowest in labor, and the glazing stays as it is.
- Add storm windows. Keeps the original sash and trim, adds a second layer of glass. A good answer on a historic facade.
- Pocket insert. A new unit sized to sit inside the old frame, which stays in the wall. Fast and tidy, but the new glass area is smaller than the old opening by the width of the old frame on every side.
- Full-frame replacement. The old window and frame come out to the rough opening and the new unit is installed as in new construction. This is the route for European windows, for the reasons in retrofitting European windows into an existing home.
If the old frame is rotten, an insert just sits a new window in a bad frame. Full-frame is the only option that fixes the cause.
Can I replace old wood windows with new wood windows?
Yes, and for many houses it is the more natural choice than switching material. New European wood windows are built differently from the originals: a laminated scantling made from three or four glued layers of kiln-dried, finger-jointed timber, factory-finished, with a sealed insulating glass unit and gaskets (I go through the build in wood window frames explained). The 68 mm (2 11/16 in) system is the usual match for a traditional house; the 92 mm (3 5/8 in) one is for a deep, substantial look and a third sealing line.
Two honest limits. First, European wood windows are casement, tilt-and-turn and fixed units, not double-hung. If your elevation depends on a double-hung rhythm of upper and lower sashes, a casement will read differently from the street, and I would show you that on a drawing before you commit. Second, if the house sits in a historic district, the commission may have rules about materials, profile and divided lights - check before ordering, not after.
Pine is the usual species for a renovation because it takes paint and stain well and is the most affordable of the five; the others are compared in pine, meranti, oak or larch. Where the exterior exposure is the original reason the old windows failed - a south or west wall with no overhang - an aluminum shell on the outside removes much of that refinishing work, and the aluminum-clad wood windows keep the same wood inside. Cladding reduces exterior upkeep, it does not remove it; the lifespan question is covered in how long do wood windows last.
How do I measure old wood windows for replacement?
For a full-frame replacement you measure the opening, not the window. The old frame comes out, so the number that matters is the rough opening behind it. Here is what I record on every opening:
| Measurement | How | Why it matters |
|---|---|---|
| Width | Three readings: top, middle, bottom | Old openings are rarely parallel; the smallest reading governs |
| Height | Three readings: left, middle, right | Same reason; a sagging sill shows up here |
| Diagonals | Corner to corner, both ways | Equal diagonals mean square; a difference tells me the opening needs shimming or a custom allowance |
| Wall depth | Interior face of the wall to the exterior face | Decides whether a 68 mm (2 11/16 in) or 92 mm (3 5/8 in) frame fits and how the trim returns |
| Sill and head condition | Probe with a screwdriver | Rot here changes the scope before the order, not after |
I do not give a single "standard" tolerance, because it depends on the system and the mounting method; the shop drawing sets it per opening. The sizing logic is in the rough opening sizing guide. Photograph every opening from inside and outside with a tape in the frame, and send them with your measurements. Measuring an old wood window the way the hardware store does it - from glass edge to glass edge - will give you a number that is too small for a full-frame unit.
Do I need to worry about lead paint on old windows?
In a house built before 1978, assume the paint on old wood windows may contain lead until a test says otherwise. In the US the EPA's renovation rule requires certified renovators and lead-safe work practices when paint is disturbed in pre-1978 homes, which includes removing and sanding old windows. That is the contractor's responsibility, but ask for their certification before the demo day, and ask whether the cost is in the quote. It is one more reason the old frames are better removed whole than sanded in place.
Replacement wooden window frames: new frame, sash only or whole unit?
People search for "replacement wooden window frames" when they want only the rotten part replaced. It is sometimes possible with an old US window, because parts are standardized. With a European laminated wood window the frame and sash are made together as one engineered unit, with gaskets, hardware and drainage slots matched, so I treat it as a whole-unit replacement. That is usually a fair trade on a house with several failed windows: you stop chasing individual repairs.
What I would specify
For a mid-century or older house with rot in the frames and a plan to stay ten years or more, I would take the old windows out entirely, survey every opening, and specify the 68 mm wood system in pine with double or triple glazing depending on climate. Where the walls are thick enough, the 92 mm frame is worth it on the cold elevations. On the one or two walls that take the full weather, I would put aluminum on the outside and keep the wood inside. If the windows are sound, only dry and drafty, I would honestly tell you to repair them and add storms - a window I do not have to sell is a better recommendation than one I do.
FAQ
Should I replace or repair old wood windows? Repair them if the frame and sill are sound and the problem is paint, putty or weatherstripping. Replace them if a screwdriver sinks into the frame or sill, or if the joints have opened. Rot in the frame means a full-frame replacement, not another coat of paint.
Can you replace old wood windows with new wood windows? Yes. New European wood windows are laminated, factory-finished and fitted with sealed glass, and they install as full-frame units. They are casement, tilt-and-turn or fixed rather than double-hung, so the look from the street changes slightly. I show that on a drawing first.
How do you measure old wood windows for replacement? For a full-frame unit, measure the rough opening: width at three heights, height at three widths, both diagonals and the wall depth, then probe the sill and head for rot. Smallest reading governs, and the shop drawing sets the final size. Do not measure glass edge to glass edge.
Are old wood windows with original glass worth keeping? Sometimes. If the wood is sound and the house has historic value, repair plus a storm window is a strong answer. If you want quiet rooms, fewer drafts and a sealed double or triple glazed unit, original glazing cannot deliver that, and replacement is the better route.
Are old wood windows worth replacing for energy savings alone? Rarely on energy alone. The case is strongest when the frames are failing as well as the glass, or when the house is being renovated and the windows are being touched anyway. Compare the actual condition of the wood first, then the glass.
Next step
Send me photos and measurements of two or three openings through request a quote and I will tell you for each one whether I would repair, add a storm, or replace - and which wood system fits the wall. If you want to see the profiles and finishes first, the Studio is a good place to start.