Double Glazing Guides
Plain-English advice on what double glazing costs, how the styles differ and how to get a fair price in 2026.
These guides are written to answer one question at a time and to tell you what to do, not to sell you windows. Start with the money questions if budget is your worry, the style questions if you are not sure what suits your home, or the technical questions if you want to understand the spec on a quote, or take the short route through Double Glazing Questions Answered if a one-paragraph reply is all you need. When you are ready to put numbers to it, the calculators turn your choices into a price range, and the costs hub holds the full 2026 price tables.
Cost Per Window
What a single window costs fitted, plus supply-only versus fully fitted.
Is Double Glazing Worth It?
When the savings and comfort justify the spend, and when to wait.
Casement Windows Explained
The most common UK style: how it works, what it costs and who it suits.
Sash Windows Explained
Vertical sliding windows for period homes, in uPVC or timber.
Tilt and Turn Windows Explained
Dual-opening windows that tilt or swing inward, ideal for flats.
Bay Windows Explained
Projecting three-pane windows priced per bay, with a recess inside.
Bow Windows Explained
Curved multi-pane windows priced per bow by section count.
French Windows Explained
Postless double-opening pairs for a clear, full-width view.
Flush Casement Windows Explained
Sashes that close flush with the frame for a period look.
Picture Windows Explained
Fixed non-opening panes for light and a view, the cheapest style.
uPVC Windows: Complete Guide
The value frame material: cost, lifespan and when to choose it.
Aluminium Windows: Complete Guide
Slim, strong frames for big openings and a modern look.
Timber Windows: Complete Guide
Authentic wood for period and conservation homes, with upkeep.
U-Values Explained
What the U-value means and the 1.4 W/m²K limit under the building regulations.
Building Regs Part L
What the regulations require of replacement windows, and who signs the work off.
Double Glazing for Landlords
What the proposed EPC C standard by 2030 means for rented homes and their windows.
FENSA Certificate
Get one, replace a lost copy for £30, or sell without one: regularisation, indemnity and the 10-year limit.
FENSA Explained
Why the FENSA certificate matters and what it proves about your install.
Double Glazing Finance
Why your installer is a credit broker, what 0% APR really costs, and the protection you only get if you borrow.
How to Avoid Being Overcharged
The sales tactics to watch for and how to read a quote like an installer.
How Long Does It Last?
Realistic lifespans for frames and sealed units, and when misting starts.
Single vs Double vs Triple
How the three glazing types compare on heat loss, cost and savings.
Window Energy Ratings
What the A++ to G band means and why A-rated is the modern standard.
Low-E Glass Explained
The invisible coating that reflects heat indoors and cuts the U-value ~40%.
Warm-Edge Spacers
How the spacer bar at the edge of the unit cuts heat loss and condensation.
Condensation on or Between Double Glazing
Inside, outside or between the panes: what each kind tells you, and how to remove it in winter.
Window Glass Replacement Cost
Cracked, smashed or blown: sealed unit prices by size and glass type, emergency glazing and insurance.
Blown Double Glazing
Why a misted unit cannot be dried out, what a new sealed unit costs, and how the job goes.
Replace a Window Handle
The three measurements that must match, and when a handle is not the fault.
Adjust Window Hinges
Most uPVC friction stays do not adjust. What actually fixes a dropped sash.
Window Will Not Close or Lock
Four causes, two of them free to fix. Check the locking points first.
Draughty Windows
Five sources, two of them free to fix. The candle test, the winter cam setting, and gasket prices.
Remove a Double Glazed Window
Frame and all. Glass out first, every fixing found, one cut to collapse the frame.
Fit a Double Glazed Window
Smallest of three, minus 10 mm on white uPVC, sill first, pack every fixing, and who certifies it.
Measure Windows for Replacement
Brick to brick, smallest of three, total deduction, check reveals, and who pays if it is wrong.
Fire Escape Windows
0.33 m², 450 mm high and wide, 1,100 mm max. What a replacement must match.
Cat Flap in Double Glazing
The unit is remade with the hole, never cut. Hole sizes by flap, the safety glass rule and prices.
Paint uPVC Windows
Paint, spray or replace, costed side by side. Where paint makers disagree, and the dark-colour risk.
Slimline Double Glazing
Heritage units for period sashes: measured U-values, Part L, consent and the thin price evidence.
Vacuum Glazing
Glass-only U-values against the whole window, named products, one-fitter prices, listed-building rules.
Stained Glass Double Glazing
Encapsulation, stick-on lead or secondary glazing: what each does to the panel, consent and costs.
Retrofit Double Glazing
Keep your frames: reglaze, new sashes, secondary glazing or film, each priced on dated sources.
Parts of a Sash Window
A labelled diagram, English and Scots names, and how the weights, cords and pulleys balance.
Acoustic Double Glazing
Standard double glazing is 29 dB; an acoustic laminated unit 40 dB. Why triple barely helps.
Adjust a uPVC Door
Height, then sideways, then compression. And why the keeps come before the hinges.
Front Door Cost
uPVC, composite, timber, aluminium, steel and flat fire doors, the extras, and Part L for doors.
Change a uPVC Door Lock
Measure the barrel, turn the key 5 to 20 degrees, buy 3-star. And when it is the gearbox instead.
Fit a uPVC Door
Fixings 50 mm into masonry, the threshold rule, and when a DIY door needs a building notice.
Trickle Vents Explained
Why most replacement windows now need them under Building Regs Part F.
Conservation Area Rules
Permitted development, Article 4 directions and what planners will accept.
Cheapest Double Glazing
The honest ways to cut the cost without ending up with a worse window.
Getting Three Quotes
How to compare quotes like-for-like and spot the red flags before you sign.
Glazing or Insulation First?
Which measure gives the better return on a tight budget, and why.
The Installation Process
Survey to sign-off: what happens at each stage and how long it takes.
Installation Day
How to prepare your home, what the fitters do, and how long it takes.
Window Removal and Disposal
What happens to your old windows, and why uPVC need not go to landfill.
Aftercare and Maintenance
Cleaning, hinges, drainage and what your guarantee and IBG actually protect.
Before you buy
Two related topics sit just outside this hub. If you are weighing one frame or spec against another, the Double Glazing Comparisons put the options side by side, including double versus triple glazing. And if you are on a low income, check whether you qualify for help before you pay: our double glazing grants guide explains the 2026 schemes, though only around 15% of households are eligible. And if the windows you are replacing are already double glazed, double glazed window replacement covers what the job involves and what the regulations require.