Window Fitting Business Profit Margins in the UK
The short answer
Window firms rarely lose money on the fitting. They lose it on survey errors and remakes, making good, access and the weeks between deposit and fit. Price each one as a line and measure every job against the quote.
- Supply-and-fit and fit-only are two businesses. Supply-and-fit carries frame margin and remake risk; fit-only is pure labour. Give each its own margin floor.
- Price = direct cost ÷ (1 − margin floor). In our 8-window example, £2,915 of cost at a 30% floor is a £4,164 price, about £520 a window.
- A wrong survey is the most expensive mistake. One remade frame can wipe out the profit on a small job, so one trained person signs off every survey.
- Compliance, making good, access and waste are lines on the quote. Replacement windows in England need a U-value of 1.4 W/m²K or better, certified through FENSA, Certass or building control.
Most window and door firms are busy. Plenty of them are busy and broke. The fitting day usually goes to plan. The money leaks before it (survey, order, deposit) and after it (making good, callbacks, remakes).
This guide is for UK window fitting business owners. It shows how to price so each job carries its own costs, and how to find which jobs actually pay. To check your own margins with us, book a free strategy call.
Where a window business makes and loses money
A window job has more moving parts than it looks. You buy a product made to your measurements, wait weeks for it, then fit it in a day or two in someone's home.
Margin goes in these gaps:
- Survey errors that turn into a remade frame and a second fitting day
- Making good reveals, plaster and decoration that were never on the quote
- Access for upper floors, bays and doors: towers, scaffold, a third pair of hands
- Waste from old frames and glass, priced as "we'll take it away"
- Scheme fees and paperwork for certifying every installation
- Lead platform fees never counted against the jobs they bring: see whether Checkatrade is worth it
Split supply-and-fit from fit-only
Treat them as two businesses with two margin floors.
| Line | Where the money is | The risk |
|---|---|---|
| Supply-and-fit (homeowners) | Frame margin + labour | Remakes, deposits, cancellations |
| Fit-only (for other firms) | Labour only | Rate pressure, waiting time |
| Commercial / new build | Volume | Retentions, CIS, programme delays |
Take last year's jobs, put each one in a line, and write down turnover, direct cost and gross margin. Most owners find one line paying for the others.
Then set your margin floor: overheads as a % of turnover (van, insurance, scheme membership, software, showroom, your salary) plus the net profit you want. Overheads 18% + target net 12% = a 30% floor. No quote leaves below it.
Build the price from cost, not from the competitor's leaflet
Market ranges are useful as a sanity check. One 2026 trade guide puts a supply-and-fit uPVC casement at £300–£600 per window and fit-only work at £75–£150 per window. Your price still has to come from your own costs.
Worked example: 8 uPVC casements, two-storey semi, supply and fit (example figures)
| Line | Basis | £ |
|---|---|---|
| Frames from the fabricator | 8 units | 1,700 |
| Labour | 2 fitters × 2 days = 4 man-days × £220 | 880 |
| Consumables | foam, silicone, fixings, trims, cills | 160 |
| Old frames and glass disposal | skip share / tip fees | 150 |
| Scheme registration | per installation | 25 |
| Direct cost | 2,915 | |
| Price at a 30% floor (÷ 0.70) | 4,164 |
That is about £520 a window: inside the market range, and every cost is paid for. Leave out the disposal, consumables and registration and you quote around £3,686. On every job like this, about £478 of price is missing.
Price access and making good as their own lines. If the client takes them out, you have a conversation about scope, not a discount on your labour.
Want your window and door rates built from your own numbers?
Book a free strategy call.
Make the survey the most controlled step in the business
One wrongly measured frame costs you the frame, a second fitting day and the client's patience. On a small job that is the whole profit.
Put a written survey sheet in place and have one trained person sign it off:
- structural opening sizes, squareness and brickwork condition
- reveals, cills, internal finishes and what will need making good
- escape windows: the replacement must open at least as wide as the old one
- ventilation: existing trickle vents, and what the new frames need
- access, parking, scaffold or tower need, and safety glazing positions
Then check the order against the survey before it goes to the fabricator. Track every remake as a cost line on the job, with the reason. After three months you will know whether the problem is a person, a product or a process.
Ordering frames the day the client signs at their kitchen table without dealing with cancellation. If the contract was made in the client's home, the 14-day cancellation rules apply. For supply-and-fit, the period can run from when the goods arrive. Read client cancelled within 14 days before you spend money on made-to-measure frames.
Put compliance on the quote, not in your overheads
Replacement windows are building work. In England:
- Energy A whole-window U-value of 1.4 W/m²K or better for replacement windows in existing homes
- Fire escape The new window must not give less escape opening than the one it replaces
- Ventilation Replacing windows must not make ventilation worse, which is why trickle vents matter
- Safety glazing in critical locations, such as low glazing and glazing near doors
A firm registered with a competent person scheme such as FENSA or Certass self-certifies the work. Anyone else has to go through building control. Either way it costs time and a fee per installation, so it is a line on the quote. Your survey sheet proves you checked it.
The Builder's Pricing Playbook
The package-by-package estimate sheet and the before-you-send quote checklist, so every window quote covers the whole job.
Get the free guideJob-cost every installation
Compare what you quoted with what happened, by line:
| Job | Type | Price | Quoted GP | Actual GP |
|---|---|---|---|---|
| Example A | 8 casements, supply & fit | £4,164 | 30% | 14% |
| Example B | Composite door, supply & fit | £1,650 | 32% | 35% |
Example A lost 16 points. In window firms that is almost always a remake, an extra fitting day or unpriced making good. Example B beat its target. That tells you what to sell more of and what to fix.
For a score of your whole business (pricing, cash, sales, systems) in four minutes, take the free Construction Business Scorecard.
Grow the business without growing the chaos
The firms that grow from one fitting team to four do three things in this order:
- Fix the price so each job pays for itself (the steps above).
- Sell on value, not on the cheapest quote. Present the quote face to face, explain the survey, the product and the certification, and follow up every open quote weekly. Ghennadi, a decorator in our mentorship, went from about £2K to £13.5K a month profit in 60 days. He did it largely by pricing properly and presenting quotes live. Individual results, not typical or guaranteed.
- Systemise the survey-to-fit chain so it does not depend on you: survey sheet, order check, fitting pack, sign-off photos.
This is the work we do one to one. Sviat Jay runs a working construction company (Craftex) and mentors owners himself, so the advice comes from someone who prices and runs jobs every week. Every business is different: one owner is strong at sales, another at running teams.
Working one to one, he finds those strengths and builds on them, aiming for results in about four months rather than a one-to-three-year program. Book a free strategy call to see where your window jobs leak.
If you would rather have someone build your rates and quote templates for you, see our construction estimating services.
Want to know which of your window and door jobs actually make money?
Book a free strategy call.
Before you send your next window quote
Regulatory points are general information for England as of October 2026. Check details with your scheme provider and building control.
Before you go
- The survey sheet is complete and signed off by one trained person
- Frames, labour, consumables, access, making good and disposal are separate lines
- Scheme registration and certification are on the quote
- The price is direct cost ÷ (1 − your margin floor)
- Cancellation rights are given in writing before frames are ordered
