How to Choose Replacement Windows for Your UK Home in 2026

Replacement windows are one of the larger home-improvement decisions you'll make: typically £8,000 – £20,000 for a full house, with a 25-40 year commitment to whatever you specify. Get it right and you have A-rated windows that outlast your mortgage; get it wrong and you spend the next decade looking at plastic that yellowed or aluminium that faded.

This guide walks through every decision in order — material, brand, specification, colour, glazing, installer — and gives you the 12 questions that separate good installers from the ones who'll cost you more than they save.

Step 1: Decide the Material

Three options for UK residential windows in 2026:

uPVC (polyvinyl chloride)

• Price: £300 – £600 per window installed at premium spec (Rehau TOTAL70)
• Lifespan: 25-30 years
• Thermal: A+ energy ratings achievable, U-values from 0.8 W/m²K
• Maintenance: zero for first 15 years, gasket replacement in years 15-20
• Colour options: standard white plus 20+ foil-wrapped colours and woodgrain effects
• Best for: budget-conscious projects, mid-market homes, straightforward specifications

Aluminium

• Price: £600 – £1,200 per window installed at premium spec (Cortizo COR-60, Schuco AWS 75)
• Lifespan: 40-50 years
• Thermal: achieves U-values from 0.9 W/m²K with current thermally broken systems
• Maintenance: zero, 25-year powder-coat guarantee
• Colour options: any RAL colour powder-coat, dual-colour options available
• Best for: premium properties, contemporary architecture, extensions, large spans

Hardwood timber

• Price: £800 – £1,800 per window installed
• Lifespan: 40-60 years with maintenance
• Thermal: U-values from 1.2 W/m²K (timber is naturally insulating)
• Maintenance: repainting every 6-10 years, re-sealing periodically
• Colour options: any paint finish, but needs repainting
• Best for: listed buildings, conservation areas requiring timber, premium period properties

For full comparison see our Aluminium vs uPVC Windows 2026 guide.

Step 2: Decide the Brand

Within each material, brand matters significantly. A premium-brand uPVC can outperform a budget aluminium; a budget-brand aluminium will underperform a premium uPVC.

uPVC brands worth considering

• Rehau (German) — the industry benchmark. TOTAL70 is the standard premium uPVC system. A+ energy rated, good sightlines, 30+ year track record, widely supported in the UK installer network. Rio is their flush sash heritage range.
• VEKA (German) — similar positioning to Rehau, strong thermal performance, slightly less commonly specified but equivalent quality
• Eurocell (UK) — lower-tier premium, better than budget but not a match for Rehau/VEKA on thermal longevity
• Liniar (UK) — mid-market; reasonable quality at a lower price point

Budget and mid-market uPVC brands are widely available; quality varies significantly. "uPVC casement window" at £200 installed is not the same product as Rehau TOTAL70 at £500 installed.

Aluminium brands worth considering

• Cortizo (Spanish) — premium benchmark. COR-60 casement, COR-Vision Plus sliders, hi-finity minimal systems. Qualicoat Class 2 powder coating, 40-year finish guarantee
• Schuco (German) — equivalent to Cortizo on quality, slightly older UK presence; AWS 75.SI+ is the premium casement system, AWS 90.SI+ is Passive House certified
• Smart Architectural Aluminium (UK) — mid-premium; Visofold bifolds, Alitherm casements. Good value for quality-focused projects that don't need the top tier
• AluK (Italian) — mid-market premium
• Origin (UK) — popular for bifold doors specifically, thinner sightlines at a mid-premium price

Hardwood brands worth considering

• Mumford & Wood — premium hardwood, conservation-area friendly
• George Barnsdale — established traditional manufacturer
• Westbury — premium hardwood with stronger factory QA
• JB Kind — mid-market hardwood

For any quote, the brand name should be specified in writing. "uPVC casement window" without a brand is a red flag.

Step 3: Choose the Specification

Four specification elements matter:

Frame U-value

Building Regulations require a minimum of 1.4 W/m²K for replacement windows in England. Target 1.2 W/m²K or lower for any specification that will still be competitive in 10 years. Premium systems routinely achieve 0.9-1.1 W/m²K.

Glass U-value

Separate from the frame. Look for: - Sealed double glazed units with argon gas fill - Warm-edge spacer bar (thermally broken spacer) - Low-E coating on one of the inner surfaces - Toughened inner pane (mandatory at low level for doors per Approved Document K) - Laminated outer pane for security at low level

Security rating

PAS 24:2022 is the minimum mandatory security standard under Building Regulations Approved Document Q (for new buildings and many replacements). Ask for it in writing. Secured by Design is an optional upgrade with specific hardware requirements.

Energy rating

A+ is the best available Window Energy Rating (WER) in the UK scheme. Target A or A+ on all replacements. B-rated is acceptable; C or below is outdated specification and should not be specified in 2026.

Step 4: Choose the Colour

The current premium colour preferences in UK glazing (based on 2024-26 order data):

For aluminium: 1. Anthracite grey (RAL 7016) — 42% of orders 2. Matt black (RAL 9005) — 18% 3. Dark grey (RAL 7021) — 9% 4. White (RAL 9016) — 9% 5. Heritage / traditional greens and browns — 7% 6. Other RAL — 15%

For uPVC: 1. White — 51% 2. Anthracite grey foil — 22% 3. Rosewood or oak woodgrain — 11% 4. Irish oak — 6% 5. Black — 5% 6. Other — 5%

Anthracite grey is the safest premium choice across both materials. It reads as contemporary, matches most property styles, and has consistently held its value in resale markets.

Dual-colour specifications (different colour inside vs outside) are increasingly popular — white interior for natural light, anthracite exterior for contemporary look. Typically adds £50-£120 per window.

Step 5: Choose the Glazing Bar Style

If your property has patterned windows (Georgian 4-pane, Victorian 3-pane, Edwardian 6-pane, Crittall steel style), decide how to preserve the pattern:

• Astragal bars — applied to the face of the glass (most common, budget-friendly, looks good)
• Between-the-glass bars — set inside the sealed unit (modern look, no visible frame)
• Full structural bars — proper divided-light window (period-accurate, significantly more expensive)

For conservation areas and listed buildings, specify full structural bars. For non-regulated properties, astragal bars are usually sufficient.

Step 6: Choose Operation Type

• Casement — hinged at the side, opens outward. Most common UK window type.
• Tilt-and-turn — opens inward (for cleaning or emergency) and tilts from the top (for ventilation). Common in apartments and modern properties.
• Sash — traditional vertical-sliding windows. Best for period properties.
• Bay / bow — projected window arrangement, requires structural planning
• Fixed — no opening, typically used as fillers alongside opening panels

Mix-and-match is standard; most UK homes have 3-5 different window types across the property.

Step 7: Pick the Installer

Critical. The installer matters more than the brand — a poor fit of a Cortizo will underperform a good fit of a budget brand.

Minimum installer requirements

• FENSA registered or Certass registered (statutory requirement for self-certifying Building Regulations)
• Insurance-backed guarantee via CPA, GGFi or QANW
• Companies House registered limited company (not a trading name)
• Public liability insurance — £5m minimum, ask for a copy
• References you can call — ideally 3 projects completed in the last 12 months within your postcode

Red flags

• Pressure to sign at survey
• Large deposit requirements (over 25% is worth questioning)
• Extreme discount claims ("£5,000 off today only")
• No written quote — verbal only
• No FENSA number provided
• Unable to name the specific window system they'll install
• Poor Google reviews or fewer than 10 reviews over 3+ years

Step 8: The 12 Questions to Ask

Before signing any quote for replacement windows:

1. Which brand and system are you installing? (Cortizo COR-60? Rehau TOTAL70? Schuco AWS 75?) 2. What U-value does the installed window achieve? (target 1.2 W/m²K or lower) 3. Is the installation PAS 24:2022 certified? (yes, every replacement should be) 4. Are you FENSA registered? What's the membership number? (verify at fensa.org.uk) 5. What insurance-backed guarantee do you offer? (CPA, GGFi or QANW are the main providers) 6. What's included in the price? (supply, manufacture, install, FENSA certificate, waste removal, trims, VAT) 7. What's NOT included? (plastering/making-good, electrical works, structural steels) 8. Who fits the windows — your own team or subcontracted? (either can be fine, but know who's turning up) 9. What's the lead time? (realistic is 6-10 weeks for bespoke orders) 10. What are your payment terms? (small deposit + balance on completion is standard; avoid large upfront requests) 11. How long is your workmanship guarantee? (expect 10 years) 12. Can I see three recent projects like mine? (ideally one within my postcode)

A competent installer will answer all 12 in writing without hesitation. An installer who hedges or won't commit is an installer who's going to be harder to deal with when something goes wrong.

Step 9: Get Three Quotes

Standard advice for any home-improvement spend. Three quotes from reputable local installers at like-for-like specifications lets you:

• Validate the market price
• Compare approaches to specification
• Identify any installer cutting corners
• Negotiate with confidence

At like-for-like spec, premium-brand aluminium from three different installers should fall within a ~15% range. Beyond that, someone is either under-specifying or over-pricing.

Step 10: Plan the Project

Realistic project timeline for a full-house replacement:

• Week 0: quotes received, installer chosen
• Week 1-2: order signed, deposit paid, manufacturing begins
• Week 6-10: installation day(s). Typical 8-10 window property = 2-3 days.
• Week 10-11: making-good (plastering, decoration) if included
• Week 11-12: FENSA certificate issued by post

Plan for the house to be mostly usable through installation — fitters usually do 2-4 windows per day and the property stays secure throughout.

Budget Planning

Realistic 2026 UK budgets for a full-house replacement:

• 3-bed semi (7-9 windows): £4,500 (budget uPVC) to £10,000 (premium aluminium)
• 4-bed detached (10-14 windows): £7,000 (budget uPVC) to £15,000 (premium aluminium)
• 5+ bed detached (15-20 windows): £10,000 (budget uPVC) to £22,000 (premium aluminium)
• Victorian terrace with heritage sash (6-8 windows): £8,000 (premium uPVC sash) to £18,000 (timber sash)

Prices include FENSA registration and 10-year insurance-backed guarantee.

Next Steps

If you are ready to start collecting quotes, request a quote from Vitrum Solutions. We install Cortizo and Schuco aluminium, Rehau uPVC, Palladio composite doors and Korniche roof lanterns across Buckinghamshire, Berkshire, Oxfordshire, Surrey, Hampshire, Hertfordshire and West London. Every quote is written and itemised, FENSA registered with a 10-year CPA insurance-backed guarantee.

For more detailed cost guidance see our aluminium windows cost guide, uPVC windows cost guide and bifold doors cost guide.