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Transparent secondary glazing prices for 2026: cost per window, what drives the price, and realistic budgets for flats, houses and period properties.
"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.
As a rough guide for 2026, expect:
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.
Larger windows use more glass and bigger frames. Tall sash windows and wide picture windows cost more than small casements.
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.
The way your secondary glazing opens affects cost. From most affordable to premium:
Listed buildings, bay windows, and curved or arched openings need bespoke fabrication, which adds cost but ensures a perfect fit.
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.
For expert secondary glazing advice and free consultations for listed buildings in London, contact Secondary Glazing Specialist on 020 7060 1572.
Eleanor Hartley
Senior Glazing Consultant
"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.
As a rough guide for 2026, expect:
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.
Larger windows use more glass and bigger frames. Tall sash windows and wide picture windows cost more than small casements.
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.
The way your secondary glazing opens affects cost. From most affordable to premium:
Listed buildings, bay windows, and curved or arched openings need bespoke fabrication, which adds cost but ensures a perfect fit.
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.
Some energy-efficiency schemes can help offset costs. We keep a running list in our 2026 window grants and schemes guide.
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.
London's leading secondary glazing specialists for Grade I, Grade II, and Conservation Area properties. Every project begins with a complimentary heritage survey.
