Sash Window Repair — Questions & Answers

Costs vary significantly depending on the condition of the timber, the number of windows, the level of work required and access. A straightforward draught-proofing job on one or two windows will cost considerably less than a full restoration involving timber repairs, re-cording, glazing work and draught-proofing.

We do not believe in giving fixed prices without seeing the windows first — no two old sash windows are the same, and a price given without a proper look is rarely accurate. A free survey is the starting point. After that you will receive a clear written estimate based on what we actually find, with no surprises when the work begins.

In the majority of cases, repair is the right answer. Original Victorian and Edwardian sash windows were made from slow-grown, dense timber that has already proven it can last — a window that has been in a house for 120 years is not a failing product. With the right repairs and draught-proofing, most of them will be good for another 50 years at least.

Replacement is often significantly more expensive than a proper restoration, particularly if you want to replace like-for-like in timber. Replacement also permanently alters the character of the building and can cause planning complications in listed and conservation area properties. We always recommend restoration where the timber allows.

Draughts in sash windows usually come from gaps between the sash and the frame — at the sides, top, bottom and meeting rail — that have opened up over time as timber moves, paint fails or the original draught strip wears out. In many older properties no draught strip was ever fitted at all.

The gaps are often small but very effective at letting cold air in, because they run the full height or width of the window. A window that feels fine in summer can be very draughty in winter when wind pressure is higher. Properly fitted AQ21 draught-proofing closes all of these gaps without affecting how the window works — and the results are immediate.

AQ21 is a purpose-made seal system for sliding sash windows, fitted alongside quality weather strip. The seals are routed into the frame and sash components to close the gaps where draughts enter — at the sides, meeting rail and top — without affecting the window's movement or appearance.

It is significantly more effective and durable than brush pile draught-proofing. The seals compress to form a proper closure when the window is shut and release cleanly when opened. It is suitable for both standard and listed building properties, and is generally the most cost-effective single improvement you can make to the thermal performance of an old house.

Yes — in many cases what looks like severe rot is localised to the area where water has been able to sit or penetrate. Where the decay is confined, splice repairs or Dutchman repairs can remove the failed timber and replace it with new matching material, leaving the bulk of the original window intact. Where a bottom rail or sill section is more extensively decayed, a full section replacement may be needed.

These repairs, done properly with appropriate timber, will outlast the original material in many cases. The key is not to leave rot to spread — early repair is always cheaper than late repair, and a rotten sill that is addressed promptly may save the whole window.

Sash cords fail through a combination of wear, UV exposure and gradual fraying at the point where they pass over the pulley or attach to the sash. In many properties the original cords have simply never been replaced and have eventually given out — which often means both cords on a sash go within a short time of each other.

Cheap replacement cord fails relatively quickly. Good quality waxed sash cord, correctly fitted and properly weighted, should last 20–30 years without problems. When we replace cords we also check the pulleys and re-balance the weights, so the sash runs smoothly and doesn't put undue strain on the new cord.

The time depends on the number of windows and the extent of the work. A single straightforward sash — re-corded, draught-proofed and with minor repairs — can typically be completed in a day. A window requiring significant timber repairs, re-glazing and full draught-proofing will take longer.

For a whole house with multiple windows in need of restoration, the work is usually planned and phased over a number of days. We will give you a realistic timescale in the written estimate so you know what to expect before anything starts. We don't rush the work — it's done properly, in the right order.

Yes — restoration is generally the preferred approach for listed buildings, and in most cases does not require listed building consent because you are repairing rather than altering the fabric of the building. Replacing windows in a listed building, by contrast, will usually require consent from your local planning authority.

We have experience working on listed properties across Powys and the Shropshire borders and understand the standards and materials these buildings require. If you are unsure about consent requirements for your specific property, your local authority conservation officer is the right person to ask — they are generally helpful and it is always worth checking before any significant work.

Draught-proofing in particular makes a noticeable difference — the improvement in warmth is usually felt immediately, especially in older houses where draughts have been tolerated for years. The energy saving from closing draughts at sash windows is well documented and typically offers good value compared to other insulation improvements.

Re-cording and restoration work also ensures the windows close properly and sit flush in their frames, which eliminates secondary sources of heat loss. The overall effect on heating bills will depend on how draughty the windows were to begin with, but the improvement is genuine and most customers notice it straightaway.

Restoration means repairing and refurbishing the existing window — replacing what has failed (cords, putty, sections of rotten timber), draught-proofing the frame, and returning the window to proper working order while keeping all original material that is still sound. Replacement means removing the original window entirely and fitting a new one.

Restoration is almost always cheaper than like-for-like timber replacement, preserves the character of the building, is appropriate for listed and conservation area properties, and avoids discarding a window that is largely still sound. Replacement may be the right answer where timber is very extensively decayed, but it should be a considered decision rather than a default one.

Yes — a significant proportion of our work is in conservation areas across Powys and the Shropshire borders. Restoration work in a conservation area typically does not require any special permission because you are maintaining existing windows rather than altering them. Changes that affect the external appearance of the building are more tightly controlled, and it is worth checking with the local planning authority if you are in any doubt.

We always work with materials and methods appropriate to the age and character of the building — the right timber, correct joinery details, sympathetic putty profiles — and we can advise on what is and is not likely to require consent for your particular property and area.

The simplest way is to call Bern on 07427 315 372, or send an email to bernztrewin@gmail.com describing what you have and what the problem is. If you can attach a few photos of the window and the surrounding frame that is helpful, and for straightforward jobs a written estimate can often be given from photos alone.

For more complex restoration or timber repair work, a free visit to look at the windows properly is the right starting point — this is at no charge and with no obligation to proceed. We cover Welshpool, Powys, Montgomeryshire, the Shropshire borders and the wider Mid Wales area. Use the contact form here if that is easier.