How Much Does Secondary Glazing Cost in 2026? A Complete Price Guide

"How much does secondary glazing cost?" is a fair question with an honest answer: it depends on your windows, the glass you choose, and how many you treat. This guide gives you real 2026 figures so you can budget with confidence—no vague sales talk.

Quick Answer: Cost Per Window

As a rough guide for 2026, expect:

• Standard specification: £300–£800 per window
• Acoustic specification (10.8mm laminate): £600–£1,200 per window
• Heritage / grid-matched units: £1,000–£2,200 per window

For a typical London flat (4–6 windows) you might budget £2,500–£6,000. For a full period townhouse (10–15 windows), £12,000–£30,000 is realistic, rising for premium acoustic specifications.

What Actually Drives the Price

1. Window Size

Larger windows use more glass and bigger frames. Tall sash windows and wide picture windows cost more than small casements.

2. Glass Specification

This is the biggest variable. Standard 4mm glass is the most affordable. Step up to 10.8mm acoustic laminate glass and the price rises—but so does noise reduction, dramatically.

3. Frame Style and Operation

The way your secondary glazing opens affects cost. From most affordable to premium:

• Fixed panels — cheapest, for windows you rarely open
• Lift-out units — affordable, removable
• Hinged casements — mid-range
• Vertical sliders — for sash windows, premium

4. Bespoke and Heritage Requirements

Listed buildings, bay windows, and curved or arched openings need bespoke fabrication, which adds cost but ensures a perfect fit.

Is It Cheaper Than Replacement Windows?

Usually, yes—and especially for period homes. Replacing original sash windows can cost £2,000–£4,000 per window, may require consent, and destroys heritage value. Secondary glazing delivers comparable thermal performance and superior acoustic performance for less. We explain why in secondary glazing vs replacing sash windows.

Can I Reduce the Cost?

• Prioritise rooms: Treat bedrooms and living rooms first, then add others later
• Mix specifications: Use acoustic glass on street-facing windows, standard glass on quiet sides
• Consider DIY for simple windows: Though professional installation performs far better—see our DIY vs professional comparison

Are There Grants Available?

Some energy-efficiency schemes can help offset costs. We keep a running list in our 2026 window grants and schemes guide.

Get an Exact Quote

These figures are guidance—your real price depends on your specific windows. A free survey gives you a precise, itemised quote with no obligation. Request your free survey or call 020 7060 1572.