Double glazing windows cost: what the job involves and who is registered to do it, and what a double glazing window cost covers per opening once the frame, the glass unit and the fitting are separated

How double glazing windows cost works

1. Start from the window schedule. Every opening gets a size, a style and a note of whether it opens. Fixed panes are the cheapest part of any run, side hung and top hung openers cost more, and tilt and turn hardware costs more again. A quote built from this schedule can be compared line by line with another one, which is the only comparison worth making.
2. Price the awkward openings separately. Bays, bows, arches, and anything above the ground floor are where the money goes. A bay needs a structural head or a corner post system because the frames above it carry load, and an upper floor needs safe access. Neither is a surcharge on a normal window, they are different jobs with their own materials and time.
3. Settle the glass make up. The sealed unit specification changes the price and the performance: the coating on the inner pane, whether the cavity is filled with argon, the spacer bar between the panes, and whether any pane is toughened or laminated. Ask for the make up in writing rather than a phrase like high performance glass.
4. Add the builder's work. Cavity closers, new internal sills, making good the plaster line, external sealing and disposing of the old frames are real hours. On an older property with timber frames and lime plaster they are a substantial share of the job, and leaving them out is the easiest way to make a quote look competitive.
5. Confirm registration and paperwork. The installer should say which competent person scheme it belongs to and that the certificate is part of the price. That certificate is what a buyer's solicitor asks for later, and its absence is a thing you have to fix at the point you least want to be fixing it.

Insurance and paperwork

Common questions

Is a whole house priced more keenly than a few windows?

Usually, because the fixed costs of a job, the survey, the delivery, the access and the setting up, are spread over more openings. That is a genuine saving rather than a sales device, but it only applies if the windows all need doing.

Does the frame colour change the price?

It can. A woodgrain foil, a colour on both faces or a non standard RAL in aluminium is a factory finish with its own lead time and cost, and white is the cheapest for that reason rather than any other.

Should the survey happen before or after I accept a quote?

A quote given without a measured survey is an estimate, however firmly it is worded. Expect a technical survey after acceptance and expect it to be able to change the figure if it finds something the salesperson did not.

Registered contractors by region

• Registered roofers in the East Midlands postcode area
• Registered roofers in the East of England postcode area
• Registered roofers in the London postcode area
• Registered roofers in the North East postcode area
• Registered roofers in the North West postcode area
• Registered roofers in the Scotland postcode area
• Registered roofers in the South East postcode area
• Registered roofers in the South West postcode area
• Registered roofers in the Wales postcode area
• Registered roofers in the West Midlands postcode area
• Registered roofers in the Yorkshire and The Humber postcode area