Windows & Glazing
What does double glazing mean?
Double glazing means two panes of glass with a gas-filled gap that cuts heat loss by 50%. Save up to £195 a year on bills. Learn how it works.
Windows & Glazing
Expert guides on double glazing, triple glazing, window types, costs, and energy ratings for UK homeowners. Find out which windows save the most energy and money.
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Windows & Glazing
What does double glazing look like?
Double glazing shows a 6–12mm spacer bar at the frame edge and a 24–28mm sealed unit. Here's how to identify it in under a minute.
Windows & Glazing
What does double glazing blown mean?
A blown double glazing seal cuts thermal efficiency by up to 50%. Learn how to spot a failed seal and whether you need a unit replacement or full window.
Windows & Glazing
What causes double glazed windows to blow?
Seal failure causes blown double glazing, not an explosion. In 2026, replacement costs £180–£250 per unit. Find out why seals fail and when to act.
Windows & Glazing
What are windows and doors called?
Windows and doors are collectively called fenestration in UK construction. Learn the official term used in Building Regulations and how it affects your home.
Windows & Glazing
What are thermal windows and doors?
Thermal windows and doors can save a typical semi-detached home up to £235 a year on heating. Learn what U-values mean and which glazing suits your home.
Windows & Glazing
What are the best windows and doors?
Triple glazing with a U-value of 0.8 W/m²K leads on energy efficiency, saving a semi-detached home £195 a year. Find the best windows and doors here.
Windows & Glazing
What are storm windows and doors?
Storm windows are secondary glazing that cut heat loss by up to 40% and save £100–£150 a year on heating. Find out if they suit your home.
Windows & Glazing
What are smart windows and doors?
Smart windows and doors control heat, light and privacy using electrochromic glass. Costs run £500–£1,000 per sq metre installed. Here is what to know before buying.
Windows & Glazing
What are double glazed windows filled with?
Argon gas fills 80% of UK double glazed windows, cutting heat loss by 30% versus air. Find out how the fill affects energy bills and what to ask your installer.
Windows & Glazing
What are composite windows and doors?
Composite windows and doors hit U-values of 1.2–1.4 W/m²K, beating standard uPVC. Find out how they work, what they cost, and whether they suit your home.
Windows & Glazing
Should you close windows and doors in a fire?
Yes, close windows and doors in a fire to contain flames and smoke. The UK Fire Kills campaign says it buys critical escape time. Learn the rules now.
Windows & Glazing
Should windows and doors be the same height?
Matching window and door heights boosts kerb appeal but isn't required by UK building regs. Here's what Part L says and how to decide for your home.
Windows & Glazing
Should double glazing have trickle vents?
Yes, double glazing should have trickle vents to meet UK Building Regulations. Learn when they are mandatory and how they prevent condensation and mould.
Windows & Glazing
Should double glazing have condensation?
No, double glazing should not have condensation on the internal glass. Condensation between panes means seal failure. Learn what to do and when to replace.
Windows & Glazing
Should double glazing get condensation on the outside?
External condensation on double glazing often means your windows are working well. Find out when a U-value below 1.2 W/m²K causes it and when to act.
Windows & Glazing
Should double glazing get condensation on the inside?
No, double glazing should not get condensation on the inside in normal use. Learn what causes it and when it signals a seal failure or ventilation issue.
Windows & Glazing
Should double glazed windows steam up?
No, double glazed windows should not steam up between panes. Learn the difference between failed seals and normal condensation, plus when to replace the unit.
Windows & Glazing
Should double glazed windows have a kite mark?
Double glazed windows should carry a BSI Kitemark to meet UK building regs, including a minimum U-value of 1.6 W/m²K. Here is what to check before buying.
Windows & Glazing
Should double glazed windows get condensation on the inside?
No, double glazed windows should not get condensation inside. Learn whether it signals a broken seal or humidity issue, and what a repair costs (£150–£400).
Windows & Glazing
Should double glazed windows get condensation?
No, double glazed windows should not get condensation between panes. Learn why seal failure causes misting and what to do next to restore your windows.
Windows & Glazing
Should double glazed windows feel hot on the inside?
A hot inner pane on double glazing signals a failed seal or high solar gain. Learn the causes and when to act, per Energy Saving Trust 2026 guidance.
Windows & Glazing
Should double glazed windows feel cold on the inside?
Cold inner panes on double glazing usually mean a failed seal. Learn what U-values to expect and why replacement costs £200–£400 per window.
Windows & Glazing
Do windows and doors need building regs approval?
Windows and doors must meet U-value standards under Approved Document L 2026. Replacements need FENSA certification or full building regs approval.
Windows & Glazing Glossary
Windows & Glazing FAQ
A full house of uPVC double glazed windows typically costs between 4,000 and 8,000 pounds for a three-bedroom semi-detached house. Individual windows range from 300 to 800 pounds depending on size and opening style. Prices include supply, fitting, and building regulations certification.
Triple glazing costs around 20 to 30 percent more than double glazing but delivers a U-value of around 0.8 compared to 1.2 for standard double glazing. The energy savings are modest for most UK homes, making it most worthwhile for north-facing rooms, noisy locations, or new builds where the price premium is smaller.
Most window replacements fall under permitted development and do not need planning permission. However, if your home is a listed building or in a conservation area, you will likely need consent. The installer must be FENSA registered or you will need separate building control sign-off.
Modern double glazed sealed units typically last 20 to 25 years. uPVC frames can last 25 to 35 years with minimal maintenance. Signs that replacement is needed include misting between panes, draughts around seals, difficulty opening or closing, and visible frame deterioration.
No UK scheme funds replacement windows on their own. The Great British Insulation Scheme closed on 31 March 2026 and only ever covered insulation, never glazing. ECO4 runs to 31 December 2026 in Great Britain only and targets insulation and heating for households on qualifying benefits; glazing is included only where it forms part of a wider whole-house retrofit. Glazing is also standard-rated for VAT at 20%, as HMRC lists double and secondary glazing as excluded from the energy-saving materials zero rate.
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Windows & Glazing
Triple glazing vs double glazing UK (2026)
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New windows cost UK (2026)
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Is Secondary Glazing Worth It for a Victorian Terraced House?
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Window security ratings for UK homes
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Windows & Glazing
Double glazed windows misting up inside, causes and fixes
Double glazed windows mist up inside when the hermetic seal around the unit fails, allowing humid air to enter the gap between the panes where it condenses. This is a…