Restoring old wooden windows: when it's worth it

Is the frame worth repairing or is it time to replace it

Start with a screwdriver, not a quote. Press the tip into the sill, the bottom rail, and the corners where water tends to sit. If it sinks in soft and crumbly, that section has rot; if it meets firm resistance, the wood is sound even if the paint looks dreadful. Box windows were built from slow-grown pine that holds up far better than most people expect once you scrape past the surface.

Localised rot at a sill or a corner joint is usually repairable: a joiner can cut out the bad section and splice in new timber, or you can do it yourself with epoxy wood filler for small pockets. Rot that has spread through the whole bottom rail, a frame that has racked out of square, or glass beading that has pulled away from swollen wood are signs the frame is past sensible repair.

Heritage-protected buildings add another factor: many façades in Kalamaja and parts of Nõmme fall under conservation rules that restrict changing window appearance or material, sometimes even the glazing pattern. Before you order replacements, check with the city or the building register whether your building is listed and what that means for the windows specifically.

What you can do yourself without special skills

A weekend with the right tools covers a surprising amount. Strip loose and flaking paint back to bare wood with a heat gun and a scraper, working in short passes so you do not scorch the timber. Sand with 120 then 180 grit, always along the grain, and wipe down with a cloth dampened in white spirit before anything else touches the wood.

Old putty that has cracked or fallen out should come away completely with a putty knife and, if needed, a bit more heat. Once the rebate is clean and primed, bed new glazing putty, tool it to a neat 45-degree angle, and let it skin over for at least a week before painting. Linseed oil putty is the traditional choice and matches how these windows were originally built.

Finish with an oil-based exterior primer and two coats of a breathable exterior paint, not a fully sealed acrylic that traps moisture in the wood. This is straightforward work with an inexpensive tool list: heat gun, scraper, putty knife, sandpaper, a glazing tool, and decent brushes.

• Heat gun and scraper for stripping old paint
• 80–180 grit sandpaper and a sanding block
• Linseed oil putty and a putty knife
• Oil-based primer and breathable exterior paint
• White spirit and clean rags for degreasing bare wood

Stopping draughts and damp without damaging the original

Draughts in box windows almost always come from the gap between the two sashes and around the opening edges, not from the glass itself. A self-adhesive silicone or brush-pile weatherstrip pressed into the rebate closes this gap without altering the frame, and it is fully reversible if it needs replacing in a few years.

Resist the urge to seal the gap between the inner and outer sash permanently with expanding foam or a fixed sealant. That gap is there by design, to let a small amount of air move and keep moisture from condensing and rotting the wood between the panes. Sealing it shut is the fastest way to turn a healthy window into a damp one.

If cold air is coming through the wall around the frame rather than the sash itself, a bead of flexible acrylic sealant at the external joint between frame and plaster is appropriate. Leave the drainage weep points at the bottom of the outer frame open; they let any moisture that does get in run back out.

When to call a painter or a window specialist

Reglazing a cracked pane, replacing rot in a joint, or getting a sash that has swollen shut moving freely again are jobs where a specialist earns their fee quickly, particularly if the house has several windows in similar condition. Our window fitting and servicing work starts from 90 € per job, priced once we have seen photos or the windows themselves.

If the wood is sound but the paint job has been neglected for years, stripping and repainting a full house of windows is exactly the kind of methodical, time-consuming task worth handing over. Our painting and decorating service starts from 12 € per job for smaller pieces of work, with larger jobs quoted as a fixed price.

For a single stuck sash, a missing piece of beading, or an odd repair that does not fit neatly into either category, our general odd jobs rate of 39 € per hour, minimum one hour, usually covers it without needing a separate quote.

The most common mistake owners make

The mistake we see most often is painting over old, cracked putty instead of removing it first. A skin of fresh paint hides the cracks for a season, but water still gets underneath, sits against the glass rebate, and starts rot exactly where you cannot see it until the pane is loose or the wood underneath is soft.

The second version of the same mistake is sealing every gap in sight in the name of stopping draughts, including the ventilation space between sashes. Within a couple of winters that shows up as condensation and black mould on the inner glass, and eventually as rot that a simple weatherstrip would have avoided entirely.

Both mistakes come from treating the window as a single sealed unit rather than a system with a few deliberate gaps. Knowing which gaps to close and which to leave is most of what separates a lasting repair from one that fails within a few years.