Flat roof rooflight installation in Suffolk and north Essex typically runs from around £1,150 for a like-for-like dome swap into a sound kerb, to £2,200 to £3,000 for a 1m by 1m flush glass unit in a new opening, up to £6,800 to £10,500 for a walk-on unit to an engineer’s design. The number depends on five things that are worth pricing separately: the unit itself, the kerb works, the membrane interface where the covering meets the upstand, the structural opening, and the internal finishing. Most quotes bundle all five into one figure, which is why three quotes can look wildly different and none can be checked. We publish the ranges and the breakdown so you can see what is in a price and what has been left out.
This page sets out the cost structure and the variables. For a worked example of the most common size, see how much a 1m by 1m rooflight costs fitted, and for several units at once, the cost of replacing several rooflights. The wider job is on flat roof skylight installation.
The published ranges
These are supply and fit for a thermally broken flush glass rooflight with solar control double glazing, a new insulated kerb, all fixings, weathering and internal trims, on a single-storey flat roof with reasonable access in the Ipswich, Suffolk and north Essex area. They assume the roof structure is sound and no upgrade beyond standard trimmers is needed.
| Unit and job type | Typical supply and fit | Days on site |
|---|---|---|
| Dome replacement, like for like, sound kerb, up to 900 x 900mm | £1,150 to £1,650 | 1 |
| Flush glass rooflight, 1.0 x 1.0m, new opening | £2,200 to £3,000 | 1 to 2 |
| Flush glass rooflight, 1.5 x 1.0m, new opening | £2,700 to £3,600 | 2 |
| Flush glass rooflight, 2.0 x 1.0m, new opening | £3,300 to £4,400 | 2 |
| Flush glass rooflight, 2.5 x 1.5m, new opening | £4,500 to £6,100 | 2 to 3 |
| Two units on one roof, 1.2 x 1.2m each | £4,300 to £5,700 | 2 to 3 |
| Electrically opening flush unit, 1.2 x 1.2m | £3,600 to £4,900 | 2 |
| Walk-on rooflight, 1.5 x 1.0m, to engineer’s design | £6,800 to £10,500 | 3 to 4 |
Ranges, not teasers. The survey confirms one fixed figure, and that figure is what you pay. Prices across every service are on our costs page.
The five parts of the price
Break any of those figures apart and it is made of the same five components. Understanding them is how you compare quotes properly.
1. The unit
The rooflight itself. A flush glass unit costs more than a dome, triple glazing more than double, solar control glass more than clear, an opening unit more than a fixed one, and a made-to-measure size more than a stock one. This is the part most quotes are clearest about, because it is a product with a price. It is also the part where a cheap quote saves money you will pay back in heat loss and yellowing, which is the whole argument on glass or polycarbonate.
2. The kerb works
The insulated timber kerb the unit sits on. On new work it is built from scratch. On a replacement, the existing kerb may be sound and reusable, or it may be rotten and need rebuilding, and that is the single biggest unknown on replacement work because it cannot be confirmed until the old unit is off. We quote a kerb rebuild as a provisional item, £350 to £900 depending on size and how much timber has gone, and confirm it with photographs. Every kerb we build is insulated as standard, not as an upgrade, for the reasons on cold bridging and damp around flat rooflights.
3. The membrane interface
Where the roof covering is dressed up the kerb and over the head. On new work into a covering being laid fresh, this is straightforward. On a retrofit into an existing roof, it means cutting the covering back, dressing it in and terminating it in the matching system, and the cost depends on which membrane it is and its condition. Where the covering is at end of life, a local dress-in is not honest and the roof needs recovering, which is priced separately.
4. The structural opening
On a new opening, the joists that are cut have to be trimmed. Up to about 1.2m across, standard doubled trimmers carry it and it is part of the base price. Beyond about 1.5m, or on anything unusual, a structural engineer’s calculation is needed, which is a few hundred pounds, and the trimming or steel it specifies is priced from that design. On a like-for-like replacement into an existing opening there is no structural cost at all, which is why replacements are cheaper than new openings of the same size.
5. The internal finishing
Forming and splaying the reveals, plasterboard, skim and trims. Whether this is in the price depends on scope: some jobs hand over with the unit fitted and the reveals ready for the customer’s own plasterer, others include finishing to a painted reveal. It is worth checking which, because a quote that excludes finishing is not comparable with one that includes it.
What moves the figure, up or down
- Rebuilding a failed kerb on a replacement: add £350 to £900, provisional, confirmed with photographs once the old unit is off.
- Correcting falls with tapered insulation: quoted separately by area, often less than people fear on a small roof.
- Triple glazing: add roughly 15 to 25 per cent on the unit cost.
- Marine-specification coating and 316L fixings throughout: included as standard within a mile of open sea, a modest addition elsewhere if you want it.
- Electric opener: a specification decision, not a later upgrade, priced into the unit and the wiring from the start.
- Rain sensor and wall controller: add £180 to £350 on an opening unit.
- Structural upgrade beyond standard trimmers: quoted once we have the engineer’s design. The biggest single variable on retrofit work.
- Scaffold on two-storey or restricted access: quoted separately.
- Full roof covering renewal where the membrane is at end of life: quoted separately, and we say honestly whether it is needed now or in five years.
The survey confirms one figure, and that figure is fixed. The ranges above are genuine, not a hook. Once your roof is surveyed you get one written price and that is what you pay, because the discovering happens at survey rather than mid-job. The only provisional item is a kerb rebuild that cannot be confirmed until the old unit is off, and that is stated up front.
Why a replacement is cheaper than a new opening
The same size unit costs less to fit into an existing opening than into a new one, and the reason is the structural component. A new opening means cutting joists, trimming them, and often an engineer’s calculation. A replacement drops into an opening that already exists, so all of that is gone. What a replacement adds instead is the unknown of the kerb condition, which is why a dome swap into a sound kerb is the cheapest job on the table and a replacement into a rotten kerb creeps toward the cost of a new opening. Which one you have is decided when the old unit comes off, and that is covered on when to replace a dome rooflight.
Why we publish this at all
No other installer in Suffolk publishes these figures, and the reason they do not is that a range invites comparison. We publish it because the alternative is three quotes with no common basis and a homeowner guessing which one has quietly left out the kerb rebuild, the falls correction or the finishing. A published range is not a promise that your job lands in the middle of it. It is a starting point that lets you read a quote and ask the right questions.
Common questions about flat roof rooflight costs
Why is there a range rather than a single price?
Because kerb condition, falls, structure, glazing and finishing all vary between roofs. The range covers honest jobs of that type. Your survey turns it into one fixed figure by confirming the specifics: whether the kerb is sound, whether the falls need correcting, whether the opening needs an engineer. Once surveyed, the price is fixed and does not move unless you change the specification.
What is the biggest hidden cost on a replacement?
The kerb. On a 1980s or 1990s dome the timber underneath is often soft, and it cannot be confirmed until the old unit is off. We quote a kerb rebuild as a provisional item, £350 to £900, and confirm it with photographs. A quote that does not mention the kerb at all on a replacement is a quote to watch.
Is a cheaper quote leaving something out?
Often, yes, and the usual omissions are the kerb rebuild, correcting the falls, the internal finishing, or specifying the glass properly. A quote with no stated U-value or g-value has not specified the glass. One that does not mention the kerb on a replacement has not allowed for it. Comparing the five components rather than the bottom line is how you spot it.
Do you charge for the survey?
The survey gives you one written fixed price with the glazing specification and U-value stated on it. Send us the roof size, whether it is new or a replacement, the covering if you know it, and where the property is, and we will arrange it. The price it produces is what you pay, with only a kerb rebuild left provisional until the old unit is off.
Get a fixed price
Send us the roof size, whether it is a new opening or a replacement, the existing covering if you know it, and roughly where the property sits. We will survey it, check the fall on all four faces, confirm the structure and the kerb, and give you one written fixed price with a 10-year workmanship guarantee behind it.
Request a fixed quote for flat roof rooflight installation in Ipswich, Suffolk or north Essex, or browse the published prices across every service first.
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.