Cost of New Windows
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Cost of New Windows
Understand what you’ll pay for new windows before getting quotes.
New windows in the UK typically cost £800–£2,500 per window installed, depending on size, material, and glazing type. uPVC double-glazed units are the most affordable. Timber and aluminium frames cost significantly more. Most homeowners use a registered installer rather than fitting windows themselves.
What Affects the Cost
The frame material is the biggest cost driver. uPVC is the cheapest and most common choice for UK homes. Timber frames cost considerably more — typically two to three times the price of uPVC — and require ongoing maintenance. Aluminium sits between the two in cost but offers slim sightlines and longevity. If you have a timber frame that needs attention rather than full replacement, see our guide on how to repair a wooden window frame.
The glazing specification affects both price and energy performance. Standard A-rated double glazing is the baseline. Triple glazing adds 15–30% to unit costs and suits colder or noisier locations. Specialist glass — such as obscured, laminated, or acoustic — carries an additional premium.
The number and size of windows directly scales the total. A full house re-glaze of six to ten windows reduces the per-unit cost versus ordering a single replacement. Bay windows, shaped openings, and large picture windows all cost more than standard casement units.
The type of window matters. Casement windows are the cheapest to manufacture and fit. Sash windows — whether sliding or mock-sash — cost more due to their mechanical complexity. If you have an existing sash that needs freeing up rather than replacing, our guide on how to fix a jammed sash window may be all you need.
Whether you are in a conservation area or listed building affects both material choice and cost. Permitted development rights may be restricted, requiring planning consent. Timber or slim-profile aluminium is usually required, ruling out standard uPVC — which adds cost. Check with your local planning authority before ordering.
The condition of the existing opening can push up trade costs unexpectedly. Rotten lintels, damaged reveals, or blown plasterwork around the frame all require additional labour. Getting this assessed during the survey stage helps avoid surprises.
UK Average Cost Breakdown
| Task | DIY Cost | Trade Cost | Notes |
|---|---|---|---|
| Standard uPVC casement (per window) | £350–£600 | £800–£1,200 | Includes supply and fit; DIY requires Building Regs self-certification |
| uPVC bay window (3-panel) | £900–£1,400 | £1,800–£2,800 | Bay poles, ceilings, and rooflets add cost |
| Timber casement (per window) | £700–£1,200 | £1,400–£2,500 | Higher material cost; requires periodic painting |
| Aluminium casement (per window) | £600–£1,000 | £1,200–£2,200 | Slim sightlines; popular in contemporary homes |
| Sash window — uPVC (per window) | £500–£900 | £1,000–£1,800 | Sliding mechanism adds complexity |
| Triple glazing upgrade (per window) | +£100–£200 | +£150–£300 | Added to base unit cost; improves U-value |
| Scaffold or access equipment (if needed) | £200–£500 | Often included in quote | Required for first-floor or higher windows |
| Building Regulations notification fee (DIY) | £100–£200 | Covered by FENSA/CERTASS registration | Required unless installer is scheme-registered |
DIY vs Tradesman — Is It Worth It?
Window replacement in the UK is a notifiable building work under Part L and Part Q of the Building Regulations. Any replacement window must meet minimum energy efficiency standards and, where applicable, security requirements. A registered installer (FENSA or CERTASS member) can self-certify their work, bypassing the need for a separate Building Control application. If you fit the windows yourself, you must notify your local Building Control office and pay a separate inspection fee — typically £100–£200 per dwelling. You will also need to obtain a compliance certificate before selling the property, so skipping this step causes problems further down the line.
The practical complexity is also high. Removing an existing frame without damaging the surrounding reveal, ensuring the new frame is level and square, applying correct expanding foam and silicone, and achieving a weathertight finish all require experience. Errors can lead to draughts, water ingress, or condensation within the wall cavity. If you are dealing with an existing seal failure rather than a full replacement, our guide on how to replace a window seal is a more suitable starting point.
For most homeowners, using a registered trade installer is the safer and more practical route. The DIY saving of £300–£900 per window is real, but only applies if you have the tools, skills, and are prepared to handle Building Regulations compliance independently. If you are confident in your measuring, see our guide on how to measure for replacement windows before ordering anything.
Regional Price Variations
Window installation costs in London and the South East typically run 20–35% higher than the UK average, reflecting higher trade labour rates and increased overheads. A standard uPVC casement that costs £900 installed in the Midlands or North of England may cost £1,100–£1,300 in London. Scotland, Wales, and Northern Ireland generally track closer to Midlands pricing, though rural areas may attract a call-out premium if specialist installers are scarce. Getting three quotes from local firms remains the most reliable way to establish a fair regional price.
How to Get the Best Price
- Get at least three written quotes from FENSA or CERTASS-registered installers — this ensures compliance is included in the price and makes comparison straightforward.
- Order multiple windows at once. Installers price a full-house job more competitively per unit than a single replacement, as mobilisation costs are shared.
- Avoid the busiest spring and summer period if you can. Installers may offer better pricing for winter bookings when demand is lower.
- Specify clearly what you want in writing before requesting quotes — frame material, glazing type, opening style, and colour — so you are comparing like for like.
- Check whether any windows qualify for government energy efficiency schemes. The Great British Insulation Scheme and ECO4 may fund or contribute towards glazing upgrades for eligible households. Check current eligibility at gov.uk.
What a Good Quote Should Include
- A clear itemised breakdown of supply and installation costs per window, including frame material, glazing specification, and any colour or finish upgrades.
- Confirmation that the installer is registered with FENSA or CERTASS and that a compliance certificate will be issued on completion.
- Details of what happens to the old frames — removal and disposal should be included, not charged separately.
- Any access requirements noted explicitly, including whether scaffolding or a cherry picker is needed and whether this is included in the quoted price.
- A written guarantee covering both the frames and the glass units — 10 years on the sealed units and frame is standard from reputable installers.
Hidden Costs to Watch For
- Remedial plastering after fitting. Removing old frames often damages the internal plasterwork around the reveal. Re-plastering and making good is rarely included in a window quote and can add £100–£300 per window if significant damage occurs.
- Lintel replacement. If a surveyor identifies a failing or undersized lintel above the window opening, this must be replaced before the new frame is fitted. Lintel work can add £400–£800 per opening and requires structural assessment.
- Decorating costs. New window boards, internal trims, and repainted reveals are not part of a standard installation. Budget separately for internal finishing if you want a complete result.
- Planning fees for restricted properties. Homes in conservation areas or Article 4 direction zones may require a planning application before windows can be changed. Local authority fees and any required heritage report add to the overall project cost.
Frequently Asked Questions
Do I need planning permission to replace windows in the UK?
In most cases, replacing like-for-like windows is permitted development and does not require planning permission. However, if your home is in a conservation area, a World Heritage Site, or is a listed building, you will likely need consent. Always check with your local planning authority before ordering.
How long does it take to have new windows fitted?
A single window replacement typically takes two to four hours for an experienced installer. A full house of six to ten windows can usually be completed in one to two days, depending on access and the complexity of the openings.
What is FENSA and do I need a FENSA certificate?
FENSA is a government-authorised scheme that allows registered window installers to self-certify compliance with Building Regulations. A FENSA certificate proves your windows were installed to the required standards and is required documentation when selling your home.
Is triple glazing worth the extra cost in the UK?
Triple glazing offers a better U-value than double glazing and reduces heat loss and noise, but the payback period through energy savings alone is long in the UK’s relatively mild climate. It is most cost-effective in exposed or particularly cold locations, or where noise reduction is a priority.
Can condensation between the glass panes be repaired without replacing the whole window?
Condensation between the glass panes means the sealed unit has failed and is allowing moisture in. In most cases, the sealed glass unit can be replaced without changing the entire frame, which is considerably cheaper than a full window replacement.
When replacing multiple windows, ask your installer to survey all openings before manufacturing begins — frames made to incorrect measurements cannot be returned and cause significant delays. A good installer will measure twice and confirm in writing before placing the order.
Sources
- Which? — New Windows: Costs and What to Look For — which.co.uk
- FENSA — Building Regulations and Window Replacement — fensa.org.uk
- GOV.UK — Windows: Permitted Development Rules — gov.uk
This guide is for general information only. Always work safely and follow manufacturer instructions. DIYnut accepts no liability for injury or damage arising from DIY work.
