A stiff or loose window can cost you up to £300 a year in wasted heating, but most fixes cost under £50.
A window that is hard to open or rattles in its frame is not just an annoyance. It can be a significant source of heat loss. Energy Saving Trust data shows that a single draughty sash window can lose as much heat as a 1m² hole in the wall (Energy Saving Trust, 2026). This can add roughly £150 to £300 to your annual heating bill, depending on your home’s size and fuel type.
A stiff or loose window can cost up to £300 a year in wasted heating, but most fixes cost under £50. For uPVC, an Allen key hinge adjustment is free. For timber, sanding and wax costs £5 to £10. Professional repair averages £40 to £80.
- A stiff uPVC window usually needs an Allen key hinge adjustment (free).
- A loose window can waste £150 to £300 annually in heating costs.
- DIY draught strips cost £10 to £30 and seal gaps up to 3mm.
- Professional window repair averages £40 to £80 per window (Checkatrade 2026).
- Replace a window only if frame rot or severe damage is present.
- A stiff or loose window can cost you up to £300 a year in wasted heating, but most fixes cost under £50.
- Quick numbers – repair cost vs. replacement cost for a single window
- The most common cause of a window that feels stiff to open
- How to identify if your window is "loose" and what that means for security and draughts
- The direct, plain-English answer to "window stiff loose" – the single fix that covers most cases
- How to verify a window installer or repair tradesperson is certified for the job
- When a stiff or loose window means the whole frame needs replacing – the £800–£2,000 decision
The direct answer is that most causes of a stiff or loose window can be fixed for under £50. Checkatrade data for 2026 shows that the average cost for a professional window repair, such as hinge adjustment or lock replacement, is between £40 and £80 (Checkatrade, 2026). A DIY fix using an Allen key or a £10 pack of draught-proofing strips is often all that is needed.
Quick numbers – repair cost vs. replacement cost for a single window
The table below compares typical costs for common window issues. Repairing a window is almost always cheaper than replacing it, but there are limits to what can be fixed.
| Issue | DIY fix cost | Professional fix cost | New window cost (fitted) |
|---|---|---|---|
| Stiff hinge (uPVC) | £0 (Allen key adjustment) | £40 – £80 | £800 – £1,200 |
| Loose handle or lock | £5 – £15 (new handle) | £50 – £100 | £800 – £1,200 |
| Sticking timber frame | £5 – £10 (sandpaper and wax) | £60 – £120 | £1,500 – £2,000 |
| Draughty gap (1–3mm) | £10 – £30 (draught strips) | £50 – £100 | £800 – £2,000 |
Replacement costs are based on FENSA and Glass and Glazing Federation data for a standard 1m x 1.2m window (FENSA, 2026).
The most common cause of a window that feels stiff to open
Stiffness in a window is almost always a hinge alignment problem (for uPVC) or a painted-shut or swollen frame (for timber). It is rarely a sign that the window itself is broken.
For uPVC windows, the friction hinge, also called a “stay” or “side-hinge”, often needs a simple adjustment. The Glass and Glazing Federation technical note on hinge adjustment explains that a 4mm or 5mm Allen key screw on the hinge block can be turned to change the compression (Glass and Glazing Federation, 2026). Turning the screw clockwise usually reduces the compression, making the window easier to open.
For timber windows, the typical fix is to sand down the painted-over contact point by 1–2mm, then apply a wax lubricant. The Wood Window Alliance maintenance guide states that this prevents the paint from binding the sash to the frame (Wood Window Alliance, 2026).
How to identify if your window is “loose” and what that means for security and draughts
A loose window is one that rattles or has a visible gap when closed. This is primarily a security and energy-efficiency concern. Secured by Design standards for 2026 state that a loose window can be forced open more easily, as the locking mechanism may not engage fully (Secured by Design, 2026).
The fix is usually replacing the window’s “shoot bolt”, which is the locking mechanism, or adjusting the “striker plate” on the frame where the lock catches. A loose handle can often be tightened by removing a small plastic cover and tightening the screws underneath.
Draught-proofing strips can close a 1–3mm gap at a low cost. Self-adhesive foam strips or brush pile seals cost between £10 and £30 per window (Energy Saving Trust, 2026). These strips are effective for minor gaps but will not fix a window that is structurally loose.
guide to draught-proofing your home
The direct, plain-English answer to “window stiff loose” – the single fix that covers most cases
For a standard uPVC casement window that is either stiff to open or loose when shut, the first fix is to adjust the hinge tension with a 4mm or 5mm Allen key. This single adjustment covers most cases.
If the window is stiff to open, turn the Allen key on the top hinge to reduce the compression. A clockwise turn on the screw usually achieves this. If the window is loose and rattles, turn the same screw anticlockwise to increase the compression, pulling the sash tighter against the frame. The Glass and Glazing Federation confirms this method as the standard adjustment for uPVC casements (Glass and Glazing Federation, 2026).
If the hinge adjustment does not resolve the issue, the problem may be with the locking mechanism or the frame itself. In that case, professional inspection is recommended.
How to verify a window installer or repair tradesperson is certified for the job
Before hiring a tradesperson for window repair or replacement, check their certification. For uPVC and aluminium windows, the installer must be registered with FENSA or CERTASS. This is a legal requirement under Building Regulations for replacement windows (GOV.UK, 2026).
For timber windows, look for Wood Window Alliance membership or a FENSA-registered timber specialist. For any structural repair, such as replacing a complete sash or frame, the tradesperson should be TrustMark registered. TrustMark is the government-endorsed consumer protection scheme for home improvements (TrustMark, 2026).
Always ask for proof of certification before work begins. Without it, you may not have recourse if the work is faulty or non-compliant.
how to find a certified window installer
When a stiff or loose window means the whole frame needs replacing – the £800–£2,000 decision
If the window frame is rotten in a timber window, or the uPVC has warped beyond adjustment, replacement is the only option. A gap over 5mm that cannot be closed by hinge adjustment or draught strips is a clear sign of frame failure. The Glass and Glazing Federation advises that when the frame structure is compromised, repair is not cost-effective (Glass and Glazing Federation, 2026).
Costs vary significantly. A standard 1m x 1.2m uPVC casement window costs between £800 and £1,200 fitted. A timber window of the same size costs between £1,500 and £2,000 fitted (FENSA, 2026). These figures include the frame, glass, and installation but exclude any structural repairs to the surrounding brickwork.
Before deciding on replacement, get at least three quotes from FENSA-registered installers. This ensures you are paying a fair market rate for a certified job.
Frequently Asked Questions
For uPVC windows, stiffness is almost always a hinge alignment problem. For timber frames, the cause is usually a painted-shut sash or wood swollen from moisture. A simple adjustment with an Allen key or sanding the frame often fixes it, as noted by the Energy Saving Trust.
A loose window that rattles is usually caused by worn hinges or a loose handle. Tightening the hinge screws or replacing the handle for £5 to £15 can stop the rattle. If the gap is between the frame and sash, add draught strips for £10 to £30, as recommended by the Energy Saving Trust.
Professional repair for a stiff uPVC window costs between £40 and £80, according to Checkatrade 2026 data. For timber windows, the cost is higher at £60 to £120 if sanding and repainting are needed. This is far cheaper than a new window, which costs £800 to £2,000 fitted.
Yes, a stiff window often means it does not seal properly, allowing draughts. The Energy Saving Trust states that a single draughty sash window can lose as much heat as a 1m² hole in the wall, adding £150 to £300 to your annual heating bill.
Replace a window only if the frame is rotting (timber), severely warped, or the glass is broken beyond repair. If the issue is a stiff hinge, loose handle, or draughty gap, a repair costing under £100 is almost always sufficient. FENSA advises replacement for structural damage only.
