Cheap aluminium windows don’t have to mean low quality. In 2025, you can buy thermally broken, A-rated aluminium casement windows for, and install them yourself to save another £100–£150 per opening. Done right, they last 35+ years, cut heating bills by 25–30%, and look slim and modern.
This guide gives you exact suppliers, real prices (checked December 2025), a quality checklist, and a full DIY install steps so you don’t waste money on rubbish or overpriced fitters Cheap Aluminium Windows.
The Real Cost of Getting This Upgrade in 2025
- Average UK semi-detached house (8 windows): £1,900 – £2,800 fully supplied
- Energy saving: £140 – £220 per year (Energy Saving Trust 2025 figures)
- Payback time: 9–14 years, then pure profit for the next 20+ years
Let’s avoid the common mistakes first.
How to Spot Junk Aluminium Windows in Under 2 Minutes
Most “cheap” failures come from three things:
- No thermal break – cold aluminium acts like a radiator in reverse. U-value jumps to 4.0+ instead of 1.4–1.6
- Thin 1.0–1.2 mm profiles that flex and leak air
- Single glazing or cheap non-argon double glazing
Quick checklist before you pay a penny:
- Frame thickness ≥ 1.4 mm (ask for section drawing)
- Polyamide thermal break (not cheap resin)
- U-value certificate ≤ 1.6 W/m²K for the whole window
- PAS 24 or Secured by Design security standard
- 10-year insurance-backed guarantee
If any of these are missing, walk away.
Here’s a real comparison table from quotes I collected last week (Dec 2025):
| Supplier | Price 1200×1200 casement | Thermal Break? | U-value | Guarantee | Delivery UK |
|---|---|---|---|---|---|
| Trade Windows Direct | £182 | Yes | 1.4 | 10 yrs | Free over £1k |
| Eurocell (Polish import) | £228 | Yes | 1.3 | 15 yrs | Free |
| Anglian clearance stock | £295 | Yes | 1.2 | Lifetime | £80 |
| Local fabricator quote | £480 | Yes | 1.4 | 10 yrs | Included in fit |
You can see where the real savings are.
Best Places to Buy Cheap Aluminium Windows in the UK Right Now (December 2025)
These are the suppliers actually delivering quality at low prices today:
- Trade Windows Direct – cheapest custom sizes, starts at £180, online only
- Express Bi-folds & Windows – Polish-made Reynaers copies, £220–£280 range
- Clearance sections of Anglian, Safestyle and Everest – end-of-line colours, up to 55% off
- Facebook Marketplace “trade” groups – ex-display windows often £100 each (check measurements!)
Pro tip: Order in anthracite grey RAL 7016 or black RAL9005 – these colours are always in stock and £20–£40 cheaper than white.
Exact Step-by-Step DIY Installation (Save £800–£1,200 on a Full House)
Tools you need (total cost <£60):
- Cordless drill
- Spirit level + laser (£25 on Amazon)
- Expanding foam gun (£30)
- Silicone + gun
7 steps I use on every job:
- Remove old window and timber subframe completely
- Check opening is square – max 3 mm out or pack with shims
- Apply two beads of low-modulus silicone on the outer brickwork
- Lift new window in, centre it, pack bottom with plastic packers
- Screw through frame into brick (6–8 fixings, 150 mm from corners)
- Foam the gap (70% fill only – it expands)
- Trim and seal internally with decorator’s caulk
Time per window: 45–60 minutes once you’ve done the first one.
Common mistake: Over-tightening screws warps the frame and breaks seals. Hand-tight + ¼ turn is enough.
Maintenance That Keeps Them Perfect for 30+ Years
- Every spring: WD-40 on hinges and locks
- Every autumn: Clean drainage channels with an old toothbrush
- Every 5 years: Replace rubber gaskets (£12 per window)
Do this and you’ll never pay for repairs.
Final Numbers for a Typical 3-Bed Semi
8 windows + 1 back door, all aluminium, thermally broken
- Supply only: £2,150 (Trade Windows Direct current price)
- DIY install: £0 labour
- Total: £2,150
- Professional quote
Start measuring your openings tonight. Order by mid-January and most suppliers deliver in 3–4 weeks. You’ll have warmer rooms and a better-looking house before spring.
