Aluminium casements cost £540 to £1,350 fitted per window in 2026, roughly 30 to 40% more than an equivalent uPVC window. In return you get a slimmer frame, more glass, and a lifespan of 30 to 40 years with almost no maintenance. Use the aluminium window calculator to price your exact specification, or read on for the complete picture before you commit.
What are aluminium windows?
An aluminium window uses a hollow aluminium alloy profile for the frame and the opening sash. Modern units use a thermally broken profile: a strip of low-conductivity polyamide is inserted through the middle of the frame to interrupt the path of heat from inside to outside. Without a thermal break, aluminium conducts heat so efficiently that it would form condensation on the interior surface in winter; with one and a good double-glazed unit, an aluminium window can meet Part L, either at 1.4 W/m²K or through a Window Energy Rating of band B.
The key advantage over uPVC is rigidity at narrow section widths. Aluminium is structurally stiffer than uPVC, so a frame that is visually narrower can carry the same pane of glass without bowing or flexing. The result is a slimmer sightline: more glass, less frame. In a casement or a large fixed picture window, the difference in visual weight is immediately apparent, particularly on a contemporary elevation where the glass is a design feature in its own right.
Finish is almost always powder coating rather than paint, which gives a hard, uniform, corrosion-resistant surface available in any RAL colour. Anthracite grey and matt black have become particularly popular on new builds and extensions over the past decade, and powder coating holds both shades without fading in the way a painted timber frame might. Style options span the full range covered in the window guides hub: casements, sliding sashes, fixed picture windows, tilt and turns, and large bifold or sliding door systems where a narrow profile makes the most difference.
Aluminium window costs in 2026
The table below shows fully fitted aluminium window costs by style, including supply, removal of the existing window, installation, sealing, making good around the frame, and the FENSA registration certificate. Picture (fixed) windows carry the lowest price because there is no opening mechanism to fit or adjust; sash and bay units carry a premium for their more complex mechanisms or larger frame assemblies. Published figures sit either side of ours. Checkatrade (June 2026) gives £350 to £600 for an aluminium window and installation, averaging £475, while Door and Window Experts (September 2026) gives £989 to £3,585 per standard window, supplied and fitted with VAT. Prices by window size and for a whole house are in our aluminium windows cost guide.
| Window style | Aluminium fitted |
|---|---|
| Casement | £540–£1,350 |
| Sash | £950–£2,030 |
| Tilt and turn | £680–£1,620 |
| Bay (per bay) | £1,690–£4,050 |
| Picture (fixed) | £410–£1,030 |
Source: DGCC 2026 dataset (aluminium fitted ranges). Checkatrade (June 2026) gives £350 to £600 per window fitted and Door and Window Experts (September 2026) £989 to £3,585; both are separate sources, not the basis of these rows.
The casement is marked as best buy because it delivers the core benefit of aluminium, slim sightlines and a long lifespan, at the lowest entry cost in the range. If you are directly weighing aluminium against uPVC on price, our uPVC vs aluminium comparison sets out the cost differential by style and lists the circumstances where each material makes sense.
A word on the ranges: the lower end of each band typically reflects a standard-size window in a straightforward opening on an accessible ground floor. The upper end covers larger pane sizes, non-standard shapes, premium ironmongery, or installation on upper floors where scaffolding or specialist access equipment is required. Always get three quotes and confirm that each price includes VAT and the FENSA certificate before comparing.
Which homes suit aluminium windows?
Aluminium performs best where the slim frame profile is a genuine advantage. Contemporary and architect-designed homes, new builds with large glazed elevations, and any property where floor-to-ceiling glass or wide picture windows form part of the design brief all suit aluminium well. Strong, thin frames can span wider openings than uPVC without visible structural reinforcement, which makes aluminium the practical choice as well as the aesthetic one when individual panes are large.
The same logic applies to bifold and sliding systems. Aluminium's narrow frame section minimises the interruption between panels, which is difficult to achieve with the wider profiles that uPVC requires for equivalent structural strength. If you are planning a bifold or a run of sliding doors onto a garden, aluminium is typically what installers recommend, and for good reason.
On older and period properties the picture changes. A Victorian terrace, a Georgian townhouse, or a pre-war home with original-style proportions rarely suits a modern slim aluminium frame. In a conservation area with an Article 4 direction, councils commonly refuse obvious uPVC and modern glazing on principal or front elevations and expect a match for the originals: timber, heritage aluminium built to a slim sightline, or slimline glazing, as our conservation area rules guide sets out. Most of those homes call for a timber window or a well-specified flush uPVC casement that follows the original proportions. Our timber windows guide covers the period-appropriate alternative in full, including the relevant planning considerations.
Slimline aluminium windows
Slimline aluminium windows are aluminium frames with a narrow sightline, the visible width of frame and opening vent, and most are sold as steel-look replacements for old steel windows. No standard defines "slimline"; it is the makers' word. Reynaers says its SlimLine 38 "has been developed to mimic the slender look of steel windows", and Smart Systems designed its Alitherm Heritage "as a direct replacement for steel windows". So compare slim windows by the sightline in millimetres, which makers and trade reviewers publish.
| System | Sightline, frame plus vent | Source |
|---|---|---|
| Smart Alitherm Heritage | 59 mm (typical) | Smart Systems, maker |
| Sheerline Classic | 59 mm | KJM Group, installer (May 2026) |
| Schüco AWS 70 SC, slim frame | 63.5 mm; its deeper frames 83 to 93 mm | Door and Window Experts (May 2023) |
| Reynaers SlimLine 38 | 67 mm minimum, open-in | Reynaers UK, maker |
| Aluco steel-look aluminium | 58 mm (fixed light 33 mm) | Aluco, maker (February 2023) |
| Steel window, for contrast | 53 mm (fixed light 36 mm) | Aluco, maker (February 2023), brand not named |
Maker and trade figures, each as that source defines its sightline. Research in lib/research/sections-batch-b-2026.md.
Even the slimmest aluminium is a little wider than the steel it copies. Aluco, which makes steel-look aluminium, explains why: original metal windows are solid, single glazed and have no thermal break, so aluminium gives "similar styling but frames that will always be a little thicker". Inside one system the saving is clear: Schüco's slim AWS 70 SC frame is 63.5 mm against 83 to 93 mm for its deeper versions.
A slim frame may pass Part L by a different route. A replacement window must reach 1.4 W/m²K or a Window Energy Rating of band B. Smart Systems lists its Alitherm Heritage window at 1.6 W/m²K with a 1.0 glass unit and WER band B, and says it complies: it passes through band B, not the U-value. Door and Window Experts puts Alitherm Heritage and Schüco AWS 70 SC at around 1.5, depending on the glass. Ask for the whole-window U-value or WER on the quote, not a frame figure; our Part L guide explains both routes.
Door and Window Experts (September 2026) prices steel-look aluminium windows at £860 to £3,965 each, supplied and fitted with VAT, in grey or matt black with standard transoms rather than glazing bars. Applied glazing bars add 15 to 20% or more, the only published premium for the style. At house level the dated sources show no clear premium: KJM Group puts a standard three-bed semi in heritage aluminium (Smart or Sheerline) at £15,000 to £20,000, which sits inside Door and Window Experts' £16,000 to £22,000 for nine standard aluminium windows on the same kind of house. No source gives a percentage premium for slimline aluminium as such. Genuine steel is the dear option: KJM puts the same house at £30,000 to £35,000 or more.
| Steel-look system | Small, 600 x 900 mm | Medium, 1,200 x 1,200 mm | Large, 1,800 x 1,500 mm |
|---|---|---|---|
| Decalu 110 | £860 | £1,130 | £1,966 |
| Smart Alitherm Heritage 400 | £890 | £980 | £2,150 |
| Reynaers SlimLine 38 | £1,150 | £1,940 | £2,880 |
| Origin OW-70 Soho | £1,880 | £3,400 | £3,965 |
Source: Door and Window Experts, steel-look window prices (updated 14 September 2026). Grey or matt black, 30 to 40 mm standard transoms rather than glazing bars. One reviewer's figures, not this site's dataset.
The usual job is replacing Crittall-style steel windows. The SPAB says mild steel windows "were produced extensively from the First World War to the 1970s", with Crittall the dominant maker, and warns that many are replaced unnecessarily: even windows that look beyond repair can often be conserved, so it is worth asking before you price replacements. Whether aluminium is accepted depends on the house. Windows of similar appearance to the originals usually need no planning application, says the Planning Portal, unless an Article 4 direction applies. In conservation areas, makers and installers say heritage aluminium is widely approved (Smart Systems, KJM Group). A listed building needs listed building consent, and Aluco, itself an aluminium maker, says the requirement there is often an exact match, "in which case only steel will do".
Slimline aluminium windows are not the same thing as slimline double glazing, and quotes for "slimline windows" can mean either. A slimline aluminium window is a whole new window with a narrow metal frame. Slimline double glazing is a thin sealed glass unit, 10 to 16 mm overall, fitted into existing timber sashes and casements so the old frames stay. Check which one you are being offered.
Aluminium versus uPVC and timber
The three principal frame materials each occupy a distinct cost and performance band. Understanding where each sits helps you decide quickly whether aluminium is the right choice for your project, and our decision tools will shortcut the reading if you would rather answer a few questions about the house than weigh three price bands yourself.
uPVC is the value baseline at £400 to £1,000 fitted per window. It suits the great majority of standard UK homes: semis, terraces, bungalows and post-war housing where cost-effectiveness and low maintenance matter most. The wider frame section is a visual trade-off, but for most homes it is entirely acceptable. Our uPVC windows guide covers the full picture.
Aluminium costs roughly 30 to 40% more than uPVC; Door and Window Experts (September 2026) puts the gap a little wider, at roughly 30 to 50%. You pay that premium for slimmer sightlines, a longer confirmed lifespan of 30 to 40 years, and a more contemporary visual profile. The extra cost is well justified on the right home; less so on a standard property where frame width is not a meaningful issue.
Timber costs roughly 60 to 110% more than uPVC, making it the most expensive of the three. It is the correct choice for period and conservation-area properties where planning requires a timber window, and for homeowners who want the warmth and authenticity of natural wood. The trade-off is maintenance: timber requires repainting every 5 to 8 years to protect the frame from moisture ingress. Our aluminium vs timber comparison explores the cost-over-life calculation if you are deciding between the two premium materials, and the material classifier among our decision tools narrows the three down to one from a handful of questions about your home.
Aluminium or uPVC depends on the house, and the honest answer is rarely the expensive one. On a modern extension or a new build, aluminium looks right and lasts longer than anything else on the market. On a 1930s semi where cost matters more than sightlines, uPVC is perfectly fine. Do not spend the extra just for the sake of it.
Double Glazing Cost Calculator Team
Lifespan, maintenance, and what to expect long term
A correctly installed aluminium window lasts 30 to 40 years. The powder-coated surface resists corrosion, UV degradation and salt air far better than painted timber, and the alloy itself does not rust. There is no seasonal swelling or shrinking with humidity changes, so the seal and draught-stripping remain effective throughout the window's life without the gradual distortion that can affect older uPVC frames over time.
Maintenance is minimal. Wipe the frames down with a damp cloth once or twice a year to remove grime and prevent build-up around the seals. Lubricate the hinges, espagnolette bolts and handles with a light silicone or PTFE spray annually. Check the rubber glazing seals for cracking every few years and replace them if they harden and pull away from the glass. Beyond that, there is very little to do across a 30 to 40 year ownership period. Compare that with timber, which needs a full repaint every 5 to 8 years, and the long-term maintenance saving for aluminium becomes a meaningful part of the value case.
Cleaning access is also worth considering when you choose the style. In an aluminium tilt and turn window, the inner sash tilts inward so you can wipe the outer face of the glass from inside the room. This is a practical advantage on upper floors where ladder access is awkward or expensive, and it is one reason the tilt and turn is a popular choice in aluminium at the mid-range of the price band.
The verdict on aluminium windows
Worth it Aluminium windows are worth the premium on the right home. Contemporary properties, large glazed openings, slim-framed picture windows and bifolds all benefit from what aluminium does best: structural rigidity at a narrow frame section. The best-buy anchor in this category is an aluminium tilt and turn at around £1,000 fitted: slim sightlines, easy internal cleaning, and a 30 to 40 year lifespan in a single specification that is difficult to match at the price. For a standard home where uPVC has served well and cost is the overriding factor, the value argument for aluminium weakens, and the uPVC windows guide is the more useful starting point. When you are ready to price your own project, the aluminium window calculator gives you a 2026 fitted range based on your window count and style in seconds.
The aluminium tilt and turn at around a thousand pounds fitted is the one to look at when someone wants the full package: slim sightlines, cleans from the inside so no ladder required, and it will outlast the decade-old uPVC it is replacing by a margin. If the look matters to you, that is the window to choose.
Double Glazing Cost Calculator Team
Frequently asked questions
A fitted aluminium casement, the entry point for the material, costs £540 to £1,350 in 2026; a bay window unit costs more, running £1,690 to £4,050 per bay. Aluminium typically costs 30 to 40% more than an equivalent uPVC window.
A well-fitted aluminium window lasts 30 to 40 years. The powder-coated finish resists corrosion and does not need repainting, so maintenance is virtually nil beyond an annual wipe and a lubrication of the hinges and handles.
For most homes where sightlines matter (contemporary houses, large glazed openings, bifolds and picture windows), yes. The slim frame profile and 30 to 40 year lifespan justify the premium. For a standard semi where cost is the main concern, uPVC at £400 to £1,000 remains the sensible default.
Neither is universally better. uPVC is the value baseline at £400 to £1,000 fitted. Aluminium costs 30 to 40% more but gives you slimmer frames, a longer lifespan and a more contemporary profile. Choose aluminium where the look matters; choose uPVC where budget is the priority.
Almost none. Powder-coated aluminium does not rust, warp or need repainting. Wipe the frames down occasionally and lubricate the hinges once a year. That is essentially all the maintenance required over a 30 to 40 year lifespan.
Yes. Powder coating can match almost any RAL colour, including anthracite grey, matt black and bespoke shades. This flexibility is one reason aluminium is popular on contemporary and architect-designed homes where the frame colour is part of the overall design.
Aluminium windows with a narrow sightline, the visible width of frame and vent, most sold as steel-look replacements for old Crittall-style steel windows. No standard defines slimline. Maker and trade figures put the sightline at 58 to 67 mm: Aluco 58, Smart Alitherm Heritage and Sheerline 59, Schüco AWS 70 SC slim frame 63.5, Reynaers SlimLine 38 67. Aluco puts a steel window at 53. They are not the same as slimline double glazing, a thin glass unit for existing timber frames.
Door and Window Experts (September 2026) prices steel-look aluminium windows at £860 to £3,965 each, supplied and fitted with VAT, and says applied glazing bars add 15 to 20% or more. For a three-bed semi, KJM Group, an installer, puts heritage aluminium at £15,000 to £20,000, inside Door and Window Experts' £16,000 to £22,000 for standard aluminium, so no clear premium shows at house level. KJM puts the same house in genuine steel at £30,000 to £35,000 or more.
They can, often through the Window Energy Rating rather than the U-value. Part L asks a replacement window for 1.4 W/m²K or a WER of band B. Smart Systems lists its Alitherm Heritage window at 1.6 W/m²K with a 1.0 glass unit and WER band B, so it complies through band B. Ask for the whole-window U-value or WER on the quote, not a frame figure.