For most UK homes, uPVC is the sensible choice: lowest cost, low upkeep, and thermal performance that matches the more expensive materials. Aluminium earns its premium on contemporary properties and large glazed openings where slim frames matter. Timber is for Victorian, Edwardian and Georgian houses, and is often a requirement in conservation areas and on listed buildings.
Here is how the three compare, and how to pick for your house.
Points to take away
- uPVC costs the least and performs well. It suits homes built roughly 1960 to 2000 and most renovations.
- Aluminium costs more and looks sharper, with slimmer frames and bigger panes. Best for modern and heavily glazed designs.
- Timber costs the most and needs recoating on a cycle, but is right for period homes and often mandatory in conservation areas.
- On insulation, a good A-rated uPVC window matches standard aluminium.
- Check your local planning rules before choosing, especially in a conservation area.
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Quick comparison
| uPVC | Aluminium | Timber | |
|---|---|---|---|
| Cost per casement, fitted | £350 to £600 | £600 to £850 | £950 to £1,400 |
| Upkeep | Occasional clean | Occasional clean | Recoat every 8 to 10 years |
| Frame lifespan | 20 to 30 years | 30 to 45 years | 30 years plus, if maintained |
| Thermal performance | Very good (A-rated) | Good (thermal break needed) | Very good |
| Frame width / sightlines | Chunkier | Slimmest | Medium, traditional |
| Colours | Foils, woodgrain effect | Full RAL range | Any paint or stain |
| Best for | 1960 to 2000 homes, budget renovations | Modern homes, large openings | Period and conservation-area homes |
uPVC: the default
uPVC is what most people mean by “double glazing”. It is the cheapest to buy and fit, needs nothing more than a wipe down, and modern profiles with A-rated glass insulate as well as anything on this list. The trade-offs are aesthetic: the frames are thicker than aluminium or slim timber, and colour options are foils bonded to white, which can look less convincing at close range than paint on wood.
For a semi or detached house built in the last 60 years, uPVC does the job for the lowest outlay. See our double glazing cost guide for the full price breakdown.
Aluminium: slim frames, modern look
Aluminium frames are strong, so they can be thin while still holding large panes of glass. That gives more glass and less frame, which is why architects specify it for contemporary extensions, big sliding doors and picture windows. It takes any RAL colour with a durable powder coat, and it will not warp or rot.
Older aluminium windows were cold, because metal conducts heat. Modern frames have a thermal break, an insulating strip through the middle of the frame, which fixes most of that. Performance is good, but a like-for-like A-rated uPVC window still edges it on pure heat loss. You pay the aluminium premium for looks and span, not for a warmer house.
Timber: for period and conservation-area homes
On a Victorian or Georgian elevation, the proportions of a timber sash or casement are part of what makes the house look right. uPVC copies of those styles rarely match the slim glazing bars and deep reveals. Modern timber windows are engineered, built from laminated sections that are more stable than solid wood, and factory-finished with a coating that lasts 8 to 10 years before it needs redoing.
The cost is the highest of the three, and the maintenance is real: skip the recoating cycle and water gets into the joints. Done properly, a timber window outlasts a uPVC one.
Conservation areas and listed buildings
This is the constraint that overrides preference. In a conservation area, your local planning authority can restrict what replacement windows are allowed, and many require timber in a matching style. On a listed building, changing the windows usually needs listed building consent, and uPVC is almost never permitted.
Check with the planning department before you order. Homeowners who fit uPVC in breach of the rules can be served an enforcement notice and made to remove them at their own cost.
Which to choose for your house
- 1960s to 2000s semi or detached, sensible budget: uPVC casement or tilt and turn.
- Modern house or a contemporary extension with big glass: aluminium.
- Victorian, Edwardian or Georgian, not in a conservation area: timber for the front elevation at least, uPVC “heritage” styles elsewhere if budget is tight.
- Conservation area or listed: timber, in the style the planners require. Confirm first.
- Rental or a quick sale: uPVC. Lowest cost, no maintenance to explain to a tenant or buyer.
Whether new windows pay back on energy bills is a separate calculation. Our guide on whether double glazing is worth it works through it.
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