Restoring timber window frames without replacing them

Perth's pre-war housing carries jarrah window joinery that is denser, more stable and more durable than almost anything you could buy to replace it. Owners are frequently told it needs replacing when what it needs is repair.

What is usually salvageable

Old-growth jarrah is remarkable timber. Frames that look terrible under sixty years of failing paint are very often structurally fine underneath.

**Salvageable:** flaking paint, surface checking, small areas of rot at the sill, loose or missing putty, sashes that stick, cords that have broken.

**Marginal:** rot extending into the joints, sills soft across their full depth, frames that have racked out of square.

**Genuinely gone:** structural members soft through their section, or joints that have failed completely.

The test is a screwdriver. Push it into the suspect area with moderate pressure. Firm resistance means sound timber under bad paint. If it sinks in, that section needs cutting out.

Where windows rot, and why

Always the same places, always for the same reason: water sitting where it cannot drain.

• **The sill**, particularly at the ends where it meets the frame
• **The bottom rail of the sash**, sitting on the sill
• **The bottom of the frame legs**, where they meet the sill
• **Behind failed putty**, where water runs down the glass and in

Every one of those is a horizontal or end-grain surface with a drainage problem. That is why the repair has to restore drainage, not just fill the hole.

The restoration sequence

**1. Assess and record.** Photograph, note which sections need cutting out.

**2. Strip the failing paint.** On pre-1970 joinery, assume lead and use wet scraping or chemical stripping with containment. Never dry sand, never heat gun above the temperature at which lead fumes — infrared strippers designed for lead work exist for this reason.

**3. Cut out and splice.** Rotten sections are cut back to sound timber and a new piece spliced in — traditionally in matching timber, epoxied and pinned. On smaller defects, a two-part epoxy wood filler designed for structural repair is appropriate. Ordinary exterior filler is not.

**4. Treat the timber.** A borate or similar preservative into end grain and repaired areas.

**5. Re-putty where needed.** Old linseed putty goes hard and falls out. Rake out the failed sections, prime the rebate, and re-putty. Putty needs to skin for a week or two before it can be painted.

**6. Prime everything.** All bare timber. End grain twice.

**7. Restore drainage.** Check that the drip groove under the sill is clear — that small channel is what stops water tracking back under the sill, and it gets filled with paint over the decades. Rake it out.

**8. Two finish coats**, and paint the putty with the coating carried a millimetre or two onto the glass to seal the junction.

Sashes that stick

Usually paint build-up in the rebates rather than swelling. Stripping the rebates back and not repainting them heavily is the fix. Do not plane a sash to fit until you have removed the paint — it will be loose and rattling in a dry summer.

For double-hung windows, a restoration is the moment to replace perished cords and check the weights. It is much cheaper with the sash already out.

Why this is worth doing

Replacement joinery in an equivalent timber is expensive, and the common alternative — aluminium — changes the character of a period house substantially and is very difficult to reverse. On a character home in Mount Lawley, Subiaco or Fremantle, original joinery is part of what the house is worth.

Restoration is more labour and less material. It is slower and it is usually the better decision.