Should I Repair or Replace My Timber Windows?

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Start With Condition, Not Age

Age alone isn't a good indicator of whether a window needs replacing. A 100-year-old timber frame made from old-growth hardwood can be in better structural condition than a 20-year-old frame made from lower-quality timber, simply because of how the materials were sourced and milled decades ago. What matters is the actual condition of the timber: whether rot is localised or widespread, whether the joinery is still sound, and whether the frame holds fixings properly.

When Repair Makes Sense

Repair is usually the right call when damage is localised — a rotten sill, a few sections of timber, sticking sashes from old paint and worn cords — rather than spread throughout the frame. It also tends to be the better option when the property sits within a heritage overlay, since street-facing replacement often requires council planning approval, while like-for-like repair generally doesn't change the external appearance and is far less likely to trigger that process. And if keeping the home's original character and street presentation matters to you, repair preserves the proportions, glazing pattern, and joinery detail that replacement windows can't fully replicate.

When Replacement Makes Sense

Replacement becomes the more practical option when timber damage is extensive across multiple structural elements of the frame, or where previous poor-quality repairs have compounded over the years to the point that sound timber is hard to find. It can also make sense if there's no heritage significance to the property and low-maintenance performance is the only priority, with no value placed on retaining original timber.

The Middle Ground: Retrofit

For many homeowners, the real choice isn't strictly repair versus replace — it's repair and retrofit. This means keeping and repairing the original frame, then fitting double-glazed insulated glass units into the existing sash to bring thermal and acoustic performance close to what you'd get from a new double-glazed window, without losing the original joinery or street appearance. It's a middle path that addresses the main reason people consider replacement in the first place — comfort and energy efficiency — without the downsides of full replacement.

Cost Isn't as Clear-Cut as It Looks

On paper, a basic replacement quote can look cheaper than restoration. But that comparison rarely includes removal and disposal of the old frames, making good to surrounding render, weatherboards or plaster, and — in heritage overlay areas — the time and potential cost of a planning permit application. Once those are factored in, repair and retrofit is often cost-comparable, and sometimes cheaper, while avoiding the risk of a permit being refused or delayed.

A Simple Way to Decide

If your windows are structurally sound with only localised damage, repair (with retrofit double glazing if you want better performance) is almost always the better choice. If damage is extensive and structural, or the property has no heritage value and low maintenance is your only goal, replacement may be worth considering. Everything in between comes down to an honest, hands-on assessment of your specific windows.