Window installation cost

Window installation cost, the fitting part of a replacement job, is usually about 25% to 35% of the total, according to MyJobQuote. For a simple casement window, fitters typically charge £100 to £150 per window to take out the old one and fit the new one. Bays, upper floors and tricky openings cost more, and so do the extras around the fitting: scaffolding, a skip and making good.

The figures on this page come from three published price guides, MyJobQuote, ExpertSure and BestBuilders, read on the date shown in each job’s sources. Where a source does not say whether its price includes VAT, we treat it as including it, as we do everywhere on this site.

What window installation cost covers

A fitted price normally covers more than the physical fitting. MyJobQuote says fitted pricing covers the windows, the professional installation, removal of the old windows, disposal of the waste and the certification. That is a fuller list than many quotes show, so check yours. A quote that only says “supply and fit” may leave out removal, disposal or the certificate.

Window installation cost per window

For a simple casement window, MyJobQuote and ExpertSure both put fitting at about £100 to £150 per window. BestBuilders gives a wider range of £150 to £400, and describes it as typically a fifth to two fifths of the total. The sources do not agree exactly, so use the range as a guide and not a price.

Some windows cost more to fit. MyJobQuote gives £200 to £400 per window for a bay, or for a sliding window that needs structural work. Fitters may also price by the day instead. MyJobQuote puts a fitter’s day rate at £200 to £350, and says a two-person team usually takes 2 to 3 days to fit ten casement windows.

Extras that add to the installation cost

The fitting figure does not include everything on site. Four extras show up most often:

• Scaffolding. Upper windows that cannot be reached from the inside or a ladder need scaffold, charged at £300 to £800 per side of the house.
• A skip. Taking away the old frames and glass costs £200 to £350 for a whole house, if it is not already included.
• Making good. Replastering and repainting the reveal after the old frame comes out is £50 to £100 per window. Some fitters include it, and some leave it to you.
• Structural repairs. If the opening has rotted or is out of square, MyJobQuote puts the repair at £200 to £500 per window, and ExpertSure puts structural work for a bay at £500 to £1,500.

These extras are why two quotes with the same fitting figure can end up far apart.

Fitted or supply only

Supply only means the windows are delivered and someone else fits them. MyJobQuote puts it at £150 to £400 per window, which leaves out installation, disposal and certification. It looks cheaper, but the saving disappears if you have to pay a fitter, and the work still has to meet the building regulations.

If the fitter is not registered with FENSA or CERTASS, building control has to inspect the job. MyJobQuote and ExpertSure put that cost at £200 to £400. FENSA says you are responsible for registering the work if your fitter does not, and that you should make sure the fitter agrees in the quote to put right anything the inspector finds. Our guide to the replacement window regulations explains who certifies what.

What to ask before you accept a quote

• Does the price cover removal, disposal and the certificate?
• Is scaffolding included, and on how many sides of the house?
• Who makes good the plaster, and is it priced per window?
• What happens if the opening needs repair once the old window is out?
• Is the fitter registered with a competent person scheme?

Put the answers next to the whole-job price for your home, such as replacement windows for a 3-bed semi, and check each quote with the quote checker. How we price explains the method behind the totals. When you are ready, get free quotes.