How Much Double Glazed Windows Cost in 2026?

27, Aug, 2026

If you are comparing prices to get your windows repaired, there are many factors to consider. One homeowner might receive a £5,000 quote for repairing their windows, whilst another gets £10,000 for what seems like similar work. 

The difference is the window size, frame material, style, glass, and installation. This guide explains how much double glazed windows cost in 2026 and what you should check before accepting a quote.

What Are the Official Figures for Casement Windows?

The Federation of Master Builders' August 2026 figures give these prices for casement windows:

These figures are useful guides rather than fixed quotes. FMB notes that prices vary with the company, window style, size and specification.

For a standard uPVC casement, budgeting around £500 to £900 per installed window gives you a useful starting point. Larger, bespoke and period-style windows can cost much more.

How Much Would Double Glazing Cost for Your House?

The number of windows quickly changes the total.

For example, if you have 10 standard uPVC windows at around £600 each, the window cost alone would be about £6,000.

Your actual project cost will also depend on:

• Removing the old windows

• Disposal of old frames and glass

• Installation

• Making good around the openings

• Access requirements

• Window style

• Glass specification

• VAT and other project costs

So, when asking how much double glazed windows cost, count your windows first. Then look at the specification of each one.

Why Is One Double Glazing Quote Twice the Price?

Two quotes might look similar but include very different work. Check whether both quotes include the same:

• Number and size of windows

• Frame material

• Glass specification

• Opening style

• Handles and hardware

• Removal and disposal

• Installation

• Making good

• Scaffolding or special access

• Certification

• Warranty

• VAT

For example, a quote for 10 basic uPVC casements should not be compared directly with 10 timber sash windows.

The cheaper quote might also exclude removal, finishing work or a higher-performing glass specification.

Ask each installer for a detailed written quote. This makes the comparison much easier.

Why Do Victorian and Period Homes Cost More?

Period properties often need more care than modern homes.

A Victorian or Edwardian property might have sash windows, bay windows, timber frames or unusual opening sizes. Replacing these with standard windows might change the appearance of the property.

Timber and sash windows also tend to cost more. FMB's 2026 figures show a large difference between standard uPVC, aluminium and timber windows.

Can You Keep Your Existing Window Frames?

You do not always need to replace the complete window. Depending on the condition of the existing frame, options might include:

• Replacing the sealed glass unit

• Repairing the existing frame

• Improving draught sealing

• Replacing the complete window

This matters in older homes where the original frames contribute to the property's appearance.

Is Double Glazing Worth the Cost?

For a home with old single glazing, replacing the windows can improve comfort as well as energy efficiency.

Double glazing can also help reduce:

• Draughts

• Cold spots

• Condensation

• Outside noise

• Heat loss

The result depends on your existing windows, property and heating use. So, treat energy savings as an estimate rather than a guaranteed return.

Triple glazing has three panes instead of two. It generally offers better insulation, but it costs more.

Energy Saving Trust currently estimates triple glazing at around 20% more than double glazing. It can make sense for homes where insulation, noise or comfort is a major concern.

What Should Be Included in Your Window Quote?

Before accepting a quote, check every item.

Your quotation should make clear:

• Which windows will be replaced

• The frame material

• Glass type and energy rating

• Window style

• Installation method

• Removal of existing windows

• Waste disposal

• Making good

• Access costs

• Certification

• Warranty

• Total price

You should also check whether the installer will provide the required compliance documentation. Replacement glazing must meet Building Regulations. Planning Portal confirms that replacement glazing is covered by these requirements.

Should You Replace Windows During a Home Renovation?

If you are already renovating your property, window replacement might form part of the wider project.

This is especially relevant if you are:

• Changing the layout

• Building an extension

• Altering window openings

• Improving insulation

• Refurbishing a period property

• Redesigning a kitchen or living space

Planning these works together helps avoid finishing one part of the property and then having to reopen it for another job.

Denham Crescent manages wider renovation and extension projects across South West London. Its service covers feasibility, permits, design, construction and project management.

Upgrade Your Windows as Part of Your Renovation

Denham Crescent helps homeowners coordinate renovation work from the early planning stage through construction and finishing. The team works on house renovations and extensions, with experience across period properties and modern homes in South West London. Clients also highlight the team's communication, workmanship and ability to manage projects from start to finish.

If new windows form part of a larger project, explore Denham Crescent's House Renovations or House Extensions services.

FAQs

How much does it cost to replace 10 double glazed windows?

Ten standard uPVC windows at around £600 each would give a starting window cost of about £6,000. Installation and other work add to the total.

Can I replace double glazing without replacing the frames?

Sometimes. If the existing frames are suitable, replacing the sealed glass units might be an option. Their condition needs checking first.

How long does double glazing last?

Energy Saving Trust says good-quality double glazed windows can last around 20 to 35 years with proper installation and maintenance.

Do replacement windows need planning permission?

Often, like-for-like replacement windows do not need planning permission. Different rules apply to flats, listed buildings and some designated areas, so check before starting work.