How much does a pitched roof rooflight cost?
Nobody can give you a number for a pitched roof rooflight without knowing four things: what the roof is covered in, what is holding it up, how you get to it, and who is finishing the ceiling below. Those four move the total far more than the choice of unit does, which is why two identical windows on two houses in the same street can land a long way apart.
Sunspire quotes in two stages. A range by email once the basics are known, then a fixed written figure after a survey. This page explains what sits inside that range and what moves a job from one end of it to the other, so that when two quotes arrive you can see what is actually different about them.
The two figures, and what separates them
The first figure is a range, and it is honest about being one. It is built from the unit type, the approximate size, the covering and the storey height, which is enough to bracket a job but not to commit to it.
The second figure is fixed, written, and follows a survey where the pitch is measured, the loft is looked into and the access is worked out. Everything between the two is the cost of uncertainty, and the survey is how that uncertainty gets removed rather than priced in. A quote that jumps straight to a fixed figure without anyone looking at the roof has priced the uncertainty into it somewhere.
The flashing kit, standard against recessed
The kit is ordered by covering, and the choice between a standard and a recessed flashing is the one line on a quote most often glossed over. A standard kit sets the frame so the glass stands slightly proud of the tiles. A recessed kit drops the frame lower into the structure so the glass sits close to flush.
Recessed costs more in the kit and more in the labour, because the trimming has to be set deeper and the covering worked tighter to the frame. On a slate or a plain clay tile it earns the difference and reads far better from the garden. On a deep profile tile it earns much less. If two quotes differ and you cannot see why, this is the first line to compare.
Structure, and whether timber trimming will do
An opening that removes one rafter in a cut roof is standard carpentry with no calculation behind it. An opening that removes two or three, or one that has to work around a purlin, is a different day’s work. An opening in a trussed roof that cannot be placed between trusses brings in an engineer.
Each of those steps adds cost, and more importantly each adds time to the programme before anything happens on site. The full picture of what trimming involves sits on does fitting a rooflight weaken the roof, and it is worth reading before comparing two structural allowances.
The covering, and how long it takes to put back
Stripping back around an opening and re-laying is a labour figure, and labour scales with how fussy the covering is.
| Covering | Relative time around an opening | Why |
|---|---|---|
| Concrete interlocking tile | Quickest | Large units, regular gauge, clips |
| Plain machine made clay | Moderate | Small tiles, more of them, broken bond |
| Natural slate | Slower | Cutting, holing, rivets on narrow pieces |
| Handmade clay peg tile | Slowest | Sorting by hand, bedding cut pieces |
Access, the largest swing on a pitched roof
This is the single biggest variable and it has nothing to do with the window. A single storey rear slope reached off a lawn may need a properly footed ladder and roof ladders. A first floor front slope over a pavement in central Chelmsford needs a scaffold, edge protection and a licence from the highway authority, and the scaffold stands for the duration of the works rather than for the day of the fit.
The scaffold is often the largest single line after the unit, and it is entirely dependent on the building. It is also the line worth planning around, because a scaffold already up for other work changes the arithmetic completely. The detail sits on whether you need scaffolding.
Internal finishing, and who is holding the trowel
The reveal is where quotes diverge without looking as though they do. One quote includes forming the lining, boarding, taping, plastering and leaving it ready for decoration. Another leaves a trimmed opening with a frame in it and the word “plastering by others” somewhere in the small print.
Both are legitimate positions and neither is a problem, provided you know which one you are reading. The splayed head and vertical sill described on the roof window installation page are worth specifying explicitly, because a square reveal costs less to form and delivers noticeably less light into the room.
Glazing upgrades, and which ones are worth the difference
Most manufacturers offer a standard double glazed unit, a solar control option, a laminated option and a triple glazed option, and each step adds to the unit cost rather than to the labour.
Solar control earns its place on a south or west facing slope, where a thirty degree plane takes the July afternoon sun almost square on. Laminated glass earns its place over a bed or a stairwell, for rain noise as much as for safety. Triple glazing earns its place less often on a pitched unit than people assume, and the reasoning is set out on energy efficient rooflights. Ordering all three when one would do is the commonest way to spend money without changing how the room feels.
What is included that people forget to ask about
Four items sit outside the obvious ones and each of them is a real cost that has to land somewhere. Waste, including the tiles that break coming off and the bags of old insulation. Protection and cleaning of the room below, which on a fitted kitchen is a genuine exercise. The Building Control notification, which Sunspire handles as part of the job. And making good the decoration where the new plaster meets the old ceiling.
A comparable quote names all four, alongside the manufacturer, the model code, the structural opening size, the glazing specification with its whole window U-value and the flashing kit by code. A single line reading “supply and fit rooflight” against one number is not a quote you can compare with anything. Wider figures across the different unit types are collected on the costs page.
Tell us about your roof
We start with the building, the covering and the slope. Then we tell you what will suit it, and what it will cost, as a fixed written number.
- Surveyed before it is priced
- 10-year workmanship guarantee
- Building Control notification handled
- New installations and replacements