Secondary Glazing Cost

2026 UK pricing: DIY kits vs professional installation, materials, and whole-house costs.

Cost per Window (2026 UK Prices)

What Affects the Price

Quotes vary between suppliers for reasons beyond the basic type. The main factors:

• Window size. Large windows and bay windows need more glass or acrylic and often a bespoke frame, pushing the price towards the top of each range or beyond it.
• Opening mechanism. Fixed panels are cheapest since there's no track or hinge hardware. Sliding and hinged versions cost more but let you open a window for ventilation without removing the secondary pane entirely.
• Glass vs acrylic. Glass looks closer to a normal window and lasts longer, but weighs more and costs more than acrylic of the same size.
• Access and fitting complexity. Upper-floor windows, awkward reveals, or unusual shapes (arched or angled tops) add labour time.
• Acoustic specification. Standard glass and laminated acoustic glass aren't priced the same, and acoustic-grade units cost noticeably more per window.

Whole-House Cost

3-bedroom semi (12 windows), DIY

£360–£1,200

3-bedroom semi, professional

£1,800–£4,800

Replacement double glazing (same house)

£4,800–£7,200

Savings vs double glazing

£3,000–£5,400 (professional) or £3,600–£6,840 (DIY)

Most households don't need to do every window in one go. A common approach is to start with the rooms that matter most, a street-facing living room for noise, or a draughty bedroom for warmth, and add more windows over time as budget allows. Because secondary glazing doesn't require touching the original window, there's no disruption penalty for doing it in stages the way there would be with a full double glazing replacement.

DIY vs Professional: What You Get

DIY kits (£30–£100 per window):

• Thin acrylic panels, usually 3–4mm
• Magnetic or clip-in attachment, which means it's removable without damaging the frame
• You measure the opening, order the kit to size, trim it if needed, and fit it yourself, usually in under an hour per window
• Lifespan of roughly 5–10 years, since acrylic scratches over time and the seals around magnetic strips degrade
• U-value improves from around 5.0 down to roughly 3.5–4.0 W/m²K, a smaller gain than professional units because the seal is less airtight
• Good for rental properties, a trial run before committing to professional units, or genuinely tight budgets

Professional installation (£150–£400 per window):

• 4–6mm glass, which looks and feels much closer to an ordinary window
• Slim aluminium or uPVC frames, colour-matched on request
• Screwed to the window reveal or original frame as a semi-permanent fixture
• Brush seals or compression gaskets that give a genuinely airtight fit
• Choice of fixed, sliding, or hinged opening depending on how you need to use the window
• Lifespan of 15–20 years with minimal maintenance
• U-value improves from around 5.0 down to roughly 2.5–3.0 W/m²K
• Best suited to long-term use, listed buildings, and situations where noise reduction is a priority

Additional Costs to Budget For

Surveyor visit. £50–£100, though many suppliers waive this if you go ahead with an order.

Acoustic-grade glass. An extra £50–£100 per window for laminated glass, worth it if noise is the main reason you're installing secondary glazing at all.

Colour matching. An extra £20–£50 per window for a RAL colour match on the frame, so the secondary glazing blends in with the existing window frames rather than standing out in white or silver.

Ventilation fittings. If the room needs trickle vents or the secondary glazing seals the window too tightly for adequate ventilation, adding vents costs a further £20–£40 per window.

Payback Time

Secondary glazing improves single-glazed windows from a U-value of around 5.0 W/m²K down to 2.5–3.0 W/m²K with a professional installation, or 3.5–4.0 W/m²K with a DIY kit. For a 3-bedroom house, that translates to an estimated £150–£250 a year saving on heating bills compared with staying on single glazing.

DIY payback

2–5 years

Professional payback

8–15 years

Double glazing payback (vs single, for comparison)

12–20 years

DIY kits pay back fastest simply because the upfront cost is so low, even though the thermal performance is weaker than a professional installation. Professional secondary glazing sits between DIY and full double glazing on both cost and payback, which is exactly why it appeals to households who want a proper long-term fix without a full window replacement bill.

When DIY Is Enough

• You're renting, and removable kits don't need landlord permission the way a permanent fixture might
• You want to trial secondary glazing in one room before committing to professional units throughout
• Budget is genuinely tight, and £360–£1,200 for the whole house is far more manageable than £1,800 upwards
• You only need winter insulation and are happy to remove panels in summer

When Professional Is Worth It

• You own the property long-term, ideally 15 years or more, so the higher upfront cost has time to pay back
• You need the best available thermal performance from secondary glazing, at 2.5–3.0 W/m²K
• Noise reduction is a priority, since professional glass and airtight seals outperform DIY acrylic kits noticeably
• The property is listed, where a proper finish matters for both appearance and long-term durability

Related Guides

• Secondary Glazing: Full Guide
• Triple Glazing
• Triple Glazing Cost

Sources

1. Energy Saving Trust, "Secondary Glazing" guidance (cost ranges and payback data, 2026).
2. Historic England, "Energy Efficiency and Historic Buildings: Secondary Glazing" (listed building guidance, 2024).
3. Which?, "Secondary Glazing: Is It Worth It?" (DIY vs professional cost comparison, 2025).
4. BFRC (British Fenestration Rating Council), "Secondary Glazing Performance" (U-value testing, 2025).
5. Selectaglaze (manufacturer), "Secondary Glazing for Listed Buildings" (case studies and pricing context, 2024).

Last reviewed: 2026-06-27