A like-for-like roof window replacement in Ipswich runs from around £1,150 for a single unit up to MK06 size, and up to about £2,100 for a larger unit or £2,900 for a pair on the same slope. A new opening cut into an existing pitched roof costs more, from around £1,900 to £3,300 depending on size, because it adds structural work and a second day. Escape-rated and conservation-style installations sit higher again. Every figure here is supply and fit, including the flashing kit matched to your covering, both collars, all fixings and reinstatement of the roof. It assumes reasonable access, sound trimmers and no structural surprises. The survey confirms the exact figure, and that figure is then fixed.
Most installers will not put numbers on a page. We do, because three quotes with no shared basis is not a comparison, it is a guessing game, and the homeowner loses it. What follows is the full picture: the price by size, then a breakdown of every component that makes up that price, then the reason a swap and a new opening are two different jobs.
Cost by job type and size
These are the headline ranges for supply and fit of a modern, thermally efficient roof window with a laminated inner pane, including the flashing kit for your covering, the insulation collar, the underfelt collar, all fixings and reinstatement of the covering. They assume reasonable access, sound trimmers and no structural work beyond what the job type states.
| Job | Typical supply and fit | Days on site |
|---|---|---|
| Like-for-like replacement, single unit up to MK06 | £1,150 to £1,650 | 1 |
| Like-for-like replacement, single unit PK10 or larger | £1,450 to £2,100 | 1 |
| Like-for-like replacement, two units same slope | £2,000 to £2,900 | 1 to 2 |
| New opening in a cut roof, single unit up to MK06 | £1,900 to £2,700 | 2 |
| New opening in a cut roof, PK10 or larger | £2,300 to £3,300 | 2 |
| Escape-rated top hung unit, new opening | £2,400 to £3,500 | 2 |
| Conservation-style recessed installation | £2,600 to £3,900 | 2 |
| New opening in a trussed roof | Quoted individually after engineer’s design | 2 to 4 |
All figures include a 10-year workmanship guarantee. The dearer end of each range reflects harder access, coastal specification, slate reinstatement or a larger or upgraded unit.
Where the money actually goes
The single figure on a quote hides a stack of separate components, and knowing them is how you read a competing quote properly. A price that looks cheap is usually cheap because one of these lines has been left out. This is the breakdown behind a typical like-for-like replacement up to MK06, with indicative ranges for each part. They are not a menu to order from, they are what adds up to the total.
| Component | What it is | Indicative range |
|---|---|---|
| Roof window unit | Supply of a centre-pivot unit, laminated inner pane, up to MK06 size | £280 to £520 |
| Flashing kit | Kit matched to your covering, slate/low-profile or profiled tile | £90 to £200 |
| Insulation collar | Pre-formed insulation jacket closing the perimeter cold bridge | £45 to £80 |
| Underfelt collar | Pre-formed collar draining underlay over the frame head | £35 to £70 |
| Fixings and sundries | Brackets, screws, packers, tapes, sealants to the correct grade | £30 to £70 |
| Labour and install | Two fitters, strip-back, set and square, collars, flashing, re-cover | £450 to £650 |
| Access | Tower with edge protection for a workable rear slope | £120 to £250 |
| Disposal | Removal and disposal of the old unit and broken covering | £40 to £80 |
Indicative only. Coastal work substitutes 316L stainless fixings and upgraded flashing at no separate charge within a mile of open sea. Internal plastering and full scaffold are separate lines, below.
Add those middle-of-range figures and you land near the middle of the £1,150 to £1,650 band, which is the point. There is no margin hidden in a vague line. The two collars together are barely a hundred pounds, and they are the first things a cheap quote drops, because leaving them off saves the fitter a hundred pounds of materials and an hour of labour while making the finished window look identical on the day.
The lines that sit outside the base price
Some costs depend on your specific roof and are quoted separately so you can see them, rather than being buried or assumed.
- Internal plastering and decoration. Where the reveal needs lining, boarding, skimming and painting, allow roughly £150 to £350 per window depending on the reveal size and finish. It is included where it is in scope and stated on the quote either way, never left ambiguous.
- Full scaffold instead of a tower. On a terrace or anything at second-floor level, a tower will not reach and a full scaffold with a working platform at eaves level is needed. That is the biggest single variable on terraced properties, often £350 to £900 depending on height, road position and how long it stands, and it is quoted separately. Our scaffolding for replacement page explains when a tower will not do.
- Slate reinstatement with matching reclaimed slate. Natural slate is slower to work and matching reclaimed slate costs more than the modern equivalent, so a slate roof adds for materials and time over a plain-tile roof.
- Rotten trimmers found at strip-back. If a trimmer has gone soft under an old leaking flashing, replacing it is priced before we proceed, shown to you, and never added quietly at the end.
- Disposal of an asbestos-cement covering. Some 1960s and 1970s roofs carry asbestos-cement slates, which need controlled removal and licensed disposal. If your covering is one of these, it is flagged at survey and priced properly.
What moves the unit price
The window itself is a small part of the total, but the specification of it does move the figure.
| Change | Effect | When it is worth it |
|---|---|---|
| Top hung instead of centre pivot | Add roughly 15 to 30 per cent on the unit | Low in the slope, with a desk or bed beneath, or as an escape window |
| Triple glazing | Add around 20 to 30 per cent on the unit | North-facing slope in a room you heat hard, less so on a small landing |
| White paint or polyurethane finish | A modest add on the unit | Any bathroom or humid room, where bare pine will not last |
| Coastal specification | Included as standard within a mile of open sea | Not an upsell, it is what the location requires at Felixstowe or Harwich |
The glass versus whole window cost page answers the question people ask most: whether replacing only the glass is cheaper. On a unit old enough to have blown, the glass is rarely still available and the frame timber is fifteen to twenty years old too, so a whole-window replacement is usually the only real option and often the only sensible one.
Why a swap costs less than a new opening
The biggest single driver of price is not the size of the window. It is whether the opening already exists.
Like-for-like replacement
The structural opening stays exactly as it is. The old unit comes out, the new one goes in, the rafters are never touched. Because the opening is trimmed and the ceiling reveal is already formed, this is a half-day to one-day job with no structural work, and Building Control involvement is limited to the Part L thermal element requirement rather than anything structural. That keeps it in the £1,150 to £2,100 range for a single unit. The detail on matching an old unit to a new one is on the roof window replacement page, and the replacement cost page breaks the swap down further.
A new opening
Cutting a new window into an existing roof means removing part of a rafter and transferring its load into doubled trimmers above and below, then into the rafters either side. On a traditional cut roof, one rafter can normally be trimmed for a window up to about 940mm wide without an engineer. That adds a day, adds the trimming and making-good, and makes the work notifiable as a structural alteration, which is why a new opening starts around £1,900 rather than £1,150. On a trussed roof, common on estates built after about 1970, you cannot cut a truss without a designed solution, so those are quoted individually after an engineer’s design. The new fitting cost page covers new openings in full.
The survey confirms the figure, and then it is fixed. The ranges here are real, not a teaser to get us through the door. Once we have surveyed the roof you get one written price, and that is what you pay, because the discovering happens at survey rather than halfway through the job. Every published price across our services is on the costs page.
Common questions about cost
Why is your quote higher than the cheapest one I got?
Usually because a cheaper quote has dropped a line from the breakdown above. The two collars, the correct flashing kit and proper access are the first things to disappear, because none of them shows on the finished window on the day. They show in the third winter, as a mould line or a leak. Ask any cheaper quote to itemise the flashing kit, the insulation collar and the underfelt collar specifically.
Is the price per window cheaper if I do two at once?
Yes, per window. Two units on the same slope share the access, the set-up and one visit, so a pair at £2,000 to £2,900 works out lower each than two separate single jobs. If both windows in a loft are the same age, replacing them together usually makes sense, because the second is likely to blow within a season or two of the first.
Will the price change once you start?
No, not unless the roof hides something the survey could not see, and the main one is a rotten trimmer under an old leaking flashing. If that turns up at strip-back we photograph it, show you and price the repair before we go on. Everything else is fixed at survey. The written figure is the figure you pay.
Does coastal specification cost extra?
No. Within a mile of open sea at Felixstowe, Harwich or Aldeburgh we fit 316L stainless fixings and upgrade the flashing as standard, and it is in the base price for those locations rather than an upsell. Estuarine spots like Woodbridge and Manningtree get upgraded fixings where sensible, not a full marine specification, because they carry moderate salt loading rather than open-sea exposure.
Get your fixed price
Send a photograph of the data plate if you can reach it, one of the window from inside, and one of the roof from the garden showing the covering. That is usually enough to place your job in one of the ranges above before anyone comes out. Then we survey, confirm the opening and the flashing kit for your covering, and give you one written price with the U-value stated on it.
That price is fixed, every installation carries a 10-year workmanship guarantee, and the installers doing the work have 25 years fitting roof windows behind them. Request a fixed quote, see the full published prices, or start from the main roof window installation page.
Thinking about this job? We survey across Ipswich, Suffolk and north Essex and give you a fixed price before any work starts, with a 10-year workmanship guarantee.