How Much to Charge for a Window Fitting Job in 2026

What a window fitting quote needs to include

"8 windows fitted — £9,000" doesn't tell a customer what they're getting, and it says nothing at all about who's signing the paperwork. Cover these ten things and there's a clear answer ready for every question — including the one that comes up at the estate agent's, three years from now:

1. 1Window count, broken down by type and room — casement, sash, tilt-and-turn, bay, bow, French doors — since price and fitting time differ sharply between them.
2. 2Frame material (uPVC, timber, aluminium, composite) and glazing spec, including obscure glass for bathrooms and any acoustic or security upgrades.
3. 3Whether you're registered with a Competent Person Scheme (FENSA or CERTASS) and will self-certify the job, or whether it will instead be notified to local authority Building Control before work starts.
4. 4The whole-window U-value the new windows will achieve — replacement windows must not exceed 1.4 W/m²K under Part L, and stating the figure shows the job was specified properly, not just 'double glazed'.
5. 5Trickle vents or another agreed form of background ventilation, required under Part F unless the customer's ventilation is otherwise adequate.
6. 6Whether the property is listed or in a conservation area, since that can restrict frame style and materials regardless of energy performance.
7. 7Removal and disposal of the existing frames.
8. 8Making good — external render repair, internal plaster patching, mastic sealant and any redecoration prep — priced separately from the windows themselves.
9. 9Access requirements: scaffold or tower hire for upper-floor or bay windows on taller properties.
10. 10The guarantee period, including whether it's insurance-backed (a FENSA or CERTASS Deposit & Warranty scheme typically covers 10 years even if the installer later stops trading), and your payment and deposit terms.

Not every window job is priced — or signed off — the same way

Window type sets the headline price. But it's the Building Regulations paperwork most customers have never heard of that decides whether this job comes back to bite them — or you — later.

Two routes to compliance — and there's no such thing as "the FENSA certificate"

Replacing windows and doors needs Building Regulations sign-off, and there are exactly two ways to get it. The route almost every homeowner has heard of is a fitter registered with a Competent Person Scheme — FENSA and CERTASS are the two names you'll see most — self-certifying the work themselves and notifying the scheme, which then issues a Building Regulations Compliance Certificate (BRCC) within 30 days. "FENSA certificate" has become the generic term for this document, but it isn't brand-specific: Certass and every other government-authorised scheme issue the identical legal certificate, just under a different name. The second route, for a fitter who isn't registered with any scheme, is notifying the local authority Building Control department directly before work starts — which means a fee and a site inspection instead of self-certification. Either route is legitimate. Skipping both isn't, and the work stays technically unauthorised even if it's fitted perfectly.

The U-value and ventilation rule hiding inside every quote

Part L of the Building Regulations sets a maximum whole-window U-value of 1.4 W/m²K for replacement windows — the lower the number, the better the window retains heat, and anything specified above that figure simply doesn't comply, regardless of how good it looks. Part F adds a linked requirement: replacement windows should include trickle ventilators (background ventilation) unless it can be shown the property is adequately ventilated another way, such as an existing mechanical ventilation system. Neither of these is a niche detail — they're the two figures a Building Control inspector, or a FENSA-registered installer's own self-certification paperwork, actually checks. Stating the U-value on the quote, rather than a vague "energy efficient double glazing," is what separates a fitter who's specified the job properly from one hoping nobody asks.

The comeback that shows up two or three years later, at completion

Nobody notices a missing compliance certificate on the day the windows go in. It surfaces when the homeowner comes to sell, and their conveyancing solicitor's standard enquiries ask for it as a matter of routine. A simply misplaced certificate is a quick fix — FENSA will reissue one for about £25, taking 2–4 weeks. Work that was genuinely never certified is a much bigger problem: the seller either applies to the local authority for a "regularisation certificate" for unauthorised work, which typically costs £300–£400 and can require fixing any defects found before it's granted, or the buyer takes out indemnity insurance at £180–£500 — an option that only exists if the installation is over a year old and the council was never separately notified about it. Either way, it can hold up completion, and mortgage lenders routinely won't proceed until it's sorted. None of that risk exists for a customer whose fitter self-certified through FENSA or CERTASS the day the job finished — which is exactly the kind of reassurance worth stating plainly on the original quote, long before anyone's thinking about selling.

How to price the work

UK window prices vary significantly by type, frame material and region, but these are a fair starting point for 2026:

• uPVC casement windows: £500–£1,250 supplied and fitted, averaging around £1,000 each.
• Sash windows: £700–£1,500, averaging around £1,200 each — timber sash replacements in period properties sit at the higher end.
• Sliding and tilt-and-turn windows: £600–£1,400, averaging around £1,100 each.
• Bay windows: £1,100–£4,000, averaging around £2,500; bow windows run £1,500–£5,000+ given the extra frames and structural support involved.
• A full house re-glaze (8–12 windows) on a typical 3-bedroom property commonly runs £8,000–£15,000 all-in.
• Labour-only rates run £25–£35/hour for an experienced fitter, or roughly £600/day for a two-person team — though most jobs are quoted as supply-and-fit, not labour alone.
• Add scaffold or tower hire for upper-floor or bay windows on taller properties, and budget a 10–15% contingency for render repairs once old frames come out.

A worked example

A 3-bed semi replacing seven ageing timber windows with uPVC, priced as separate lines rather than one round number:

£8,675 for six casement windows and a 3-panel lounge bay, all specified to a 1.2 W/m²K U-value with trickle vents fitted — comfortably inside the 1.4 W/m²K Part L maximum. Old timber frames removed and disposed of responsibly, render made good around each opening, and the job self-certified through FENSA, with the customer's Building Regulations Compliance Certificate landing within 30 days of completion — one document they'll never have to think about again, including the day they come to sell.

Five details that get window fitting quotes accepted faster

• Name the certification route on the quote, not just "building regs compliant." "FENSA registered — self-certified, Building Regulations Compliance Certificate issued within 30 days" tells a customer exactly what they're getting and why they'll never need to chase a certificate when they come to sell.
• State the U-value figure, not just "energy efficient." "1.2 W/m²K whole-window U-value (better than the 1.4 Part L maximum)" is a specific, checkable claim — a customer comparing quotes will notice which fitter can actually back up the energy-saving pitch.
• Separate making-good from the window price. External render repair and internal decorating touch-up are real time on top of the fit itself — folding it into the window cost just makes your quote look more expensive than a fitter who itemises it honestly.
• Mention the insurance-backed guarantee explicitly. "10-year FENSA Deposit & Warranty cover — protected even if we ever stop trading" answers the one worry every homeowner has about paying a deposit to a small trader, before they have to ask.
• Flag conservation area or listed status up front. Raising it on the quote, before ordering frames, avoids the conversation nobody wants to have after uPVC has already been fitted somewhere it needed planning consent.

The fastest way to do all of this

One replacement window is easy enough to price on a doorstep visit. A full house of seven or eight, in three different styles, with a U-value figure, a certification route and a making-good allowance that all need to add up correctly — and stay attached to the right window in the right room — is exactly where a rushed verbal quote leaves a gap that surfaces years later at completion.

This is what QuoteRocket is for. Describe the job in plain English — "6 uPVC casement windows, 1 lounge bay window, remove and dispose of old timber frames, make good render and internal sealant, FENSA self-certify" — and it turns that into a branded, itemised PDF quote in under a minute, with every window, disposal cost and certification line kept separate and clearly labelled. Your customer accepts it with one tap on their phone, and an accepted quote becomes an invoice in one click — the fixed total they agreed to before a single frame came out.

Whichever way you produce the quote, the principle holds: state your certification route by name, put a real U-value figure on the page instead of "energy efficient," and separate making-good from the window price. It's the difference between a customer who's thrilled with their new windows today, and one who's still thrilled with them — and with you — the day their solicitor asks for the paperwork.

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