Windows wear out slowly, so nobody notices the day it happens. The draught becomes normal, the handle needs a shove, one pane mists every January. Then the gas bill arrives. Walk round the house with this checklist and sort what you find into repairs and replacements.
The quick sort
What each sign usually means
| What you see | Usually means | Likely route |
|---|---|---|
| Mist or film between the panes | Failed sealed unit | New units, if the frame is sound |
| Cold air round a closed window | Worn seals, dropped hinges or a warped frame | Adjust or re-seal first, replace if the frame has moved |
| Soft timber with a screwdriver | Rot | Repair small areas, replace if widespread |
| Yellowed or chalky uPVC | Age and sun damage | Cosmetic if sound, replace if brittle or split |
| Casement drops on its hinges | Worn hinges or a heavy sash | Re-hang or replace |
| Hardware you cannot get parts for | Discontinued system | Replace |
| Single glazing | Poor insulation | Replace or reglaze |
If glass is the only problem, our double glazing replacement service covers new units in existing frames. If the frame is the problem, a new uPVC casement window is the usual answer for a modern house, and a sliding sash for a period one.
Hampshire patterns
- Salt on the glass and corrosion on the hinges, near the Solent shore, in places like Southsea, Hayling Island and Lee-on-the-Solent.
- Condensation on the inside of the glass every morning in the long damp winters, which can point to poor ventilation as much as poor windows.
- First-generation uPVC from the 1980s and 1990s on larger estates, where seals and hinges are now at the end of their life.
- Rotten bottom rails and sills on timber windows in exposed positions, particularly on west-facing walls.
- Single glazing or secondary glazing left in older terraces and cottages.
A fifteen-minute walk round
Do this on a cold, bright morning when condensation and draughts are easiest to spot. Take a torch, a screwdriver and a notebook, and photograph anything you find.
- Close every window and run the back of your hand round the edges. Note any cold air.
- Look for mist or a milky film between the panes. Write down which windows.
- Press a screwdriver tip into timber sills and bottom rails. Soft wood is rot.
- Open and close each sash. Does it stick, drop or need lifting?
- Check the seals. Are they hard, cracked or missing in places?
- Look at the corners of uPVC frames for splits or gaps at the welds.
- Check locks and handles. If a key or handle is loose, note it.
If most of the notes are about the glass, repair is likely. If they are about the frames, you are heading towards replacement. Our guide to misted, draughty or failed double glazing goes through each fault in detail.
A sound frame with a failed unit is cheaper to fix than to replace. A reputable installer will say so. If every window gets the same recommendation, ask for a second opinion.
When replacement is probably right
- The same fault appears in most windows, not just one
- Frames are warped, rotten or split
- You are paying to heat the outdoors and the house is still cold
- The cost of repairs is approaching the cost of new windows
When you reach that point, the cost guide for double glazing replacement shows what to expect, and the cost calculator lets you try your own numbers.
How to check your windows
- Test for draughts
Close every window and run the back of your hand round the edges on a cold day, noting any cold air.
- Look for misting
Check each pane for moisture or a milky film between the two layers of glass.
- Probe the timber
Press a screwdriver tip into sills and bottom rails. Soft wood means rot.
- Operate every sash
Open and close each window. Note any that stick, drop or need lifting.
- Inspect seals and corners
Look for hard or missing seals and for splits at the corners of uPVC frames.
- Check the hardware
Test locks, handles and stays. Note anything loose or worn.
Frequently asked questions
How do I know if my windows need replacing?
Common signs are misted glass, draughts round closed windows, soft or rotten timber, warped frames and hardware that no longer works. If the same fault shows in most windows, replacement is likely.
Can I replace just the glass?
Yes, if the frame is sound. A failed sealed unit can be swapped without touching the frame, which costs far less than a new window.
How long do double glazed windows last?
Many last 20 to 25 years, though seals and hardware often fail sooner. Quality, exposure and fitting make a large difference.
Will new windows cut my heating bills?
They can, particularly if the existing glass is single, failed or very old, but savings depend on the rest of the house. Walls, roof and ventilation matter too.
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