Are my windows really the problem, and what are the alternatives to replacing them?
Old windows are often blamed for cold rooms when the real issue is the failed seals around them or the cold air pooling on their internal surface. Sash and casement windows that look beyond repair are often very repairable, and secondary glazing can deliver thermal performance comparable to double glazing while preserving the original window. Replacement is sometimes the right answer but not always.
What it usually looks like
These are the symptoms readers describe most often. None of them alone is diagnostic, but together they build a picture.
- Cold air falling onto the sill in winter
- Whistle or rattle in strong wind
- Curtains move on still days
- Single-glazed sash visibly loose in the frame
Most common in: Victorian terrace · Edwardian semi-detached · Interwar semi (1920s–1930s)
Before you buy anything
Watch the house respond as you scroll.
These checks are listed in the order we would work through them. The illustration on the left changes with each one, so you can see what each check is actually addressing before deciding whether it is worth doing.
Heat leaves through every uninsulated surface. The room cools faster than the boiler can refill it.
Try draught proofing the existing windows first
A specialist sash refurbisher can transform a Victorian window for a fraction of the cost of replacement, and it preserves the character of the house.
Measure the surface temperature of the glass
Cold glass triggers a falling air current that feels like a draught even when there is no leak. Insulating curtains, blinds or secondary glazing addresses this differently from replacement.
Look at the frame seals on existing double glazing
Many sealed units fail at the seal long before the glass clouds. The frame seal is replaceable on most modern windows for a small amount.
Consider secondary glazing for listed or characterful properties
Secondary glazing improves U-values and acoustic performance dramatically while leaving the original window in place. It is also reversible.
If replacing, model the payback against insulation
Windows are usually the most expensive fabric upgrade per square metre of heat loss saved. Loft and walls typically pay back faster.
Products that may help
Only consider these once the checks above have been ruled out. A product fitted into the wrong cause is rarely satisfying.
The cheapest answer to old windows feel draughty is usually the one that addresses the cause rather than the symptom. The list above is in the order we would work through it, because the checks at the top tend to rule out the most expensive mistakes further down.
Run the Home Comfort Score for this room
A two-minute reading gives you a number to compare against after each improvement, so you know what is actually working.