How we price, and how to read a quote

A range by email, then a fixed written figure

Sunspire quotes twice. First a range by email, once the basics are known. Then a fixed written figure after a survey, which is the one that goes on the contract and does not move unless you change what you have asked for.

The reason for two is that the second depends on things nobody can see from a photograph. A range is honest about that uncertainty rather than hiding it: wide enough to contain the likely outcomes, narrow enough to tell you whether the project is the right order of magnitude for what you had in mind.

What the emailed range is built from

Five things get you a useful range. Which town, because access and travel differ across the county. What is on the roof, because clay, concrete, slate and a single ply membrane are four different amounts of labour. Roughly which way the slope faces, because that drives the glass. The approximate size of the room below, which sets a sensible glazing area. And a photograph of the roof from outside plus the ceiling from inside.

Those two photographs do more work than any description. The outside one shows the covering, the pitch, the ridge and whether there is anywhere to stand. The inside one shows the ceiling line and often reveals a truss or a boxed duct that changes the answer entirely.

Size, and the point where the line bends

Size is the biggest single driver and the one most often misunderstood, because people assume a rooflight twice the area costs twice as much. It does not. The line runs fairly gently up to about a metre and a half in either direction, then it bends sharply.

Two things happen at that threshold at once. The glass leaves the range of standard sizes held in stock and becomes a made to order special, priced and lead-timed differently. And the opening gets large enough that timber trimming stops being adequate, so the structure has to be designed rather than assumed. Both are a step rather than a slope, which is why a modest reduction in a stated dimension sometimes produces a disproportionate saving.

On a roof that has not been built yet, landing the opening on a standard glass size is usually free: the trimmers simply go in a little further apart or closer together. On an existing roof it is rarely worth altering structure to chase one, because the cutting costs more than the glass saves.

Access, and when scaffold joins the job

Access is the driver people forget, and on some jobs it moves the figure more than the glass does.

A single storey rear extension reached across a level garden is straightforward: a tower goes up, material goes over, waste comes down. A second or third storey slope, a roof over a narrow side return with a neighbour’s fence against it, or anything where the only route runs through the house changes that. Scaffold carries a hire period as well as an erection cost, and it brings its own lead time. A garden reached only through a kitchen is doing quiet work on the price long before anyone discusses glass.

Structure, and what a steel brings with it

Where an opening is large enough to need a steel, the beam is rarely the expensive part. What comes with it is.

A structural engineer produces a calculation and Building Control wants to see it. The beam has to be got into position, which on a first floor with restricted access can mean craning or splitting the work. Padstones may be needed where it bears. The programme lengthens, and a longer programme carries more days of everything else. This is the single largest fork in a rooflight budget, which is why it is established at survey rather than on the second morning.

Glazing specification, the choice with the widest spread

The specification of the sealed unit itself has a wider spread than any other single line, because it is where a plain double glazed unit and a solar controlled, laminated, asymmetric, triple glazed one sit at opposite ends of the same catalogue.

Each step up buys something specific. Solar control glass holds down summer heat gain on a south or west facing plane and on any flat roof. Laminated outer glass reduces rain noise and improves security where the roof is reachable. A warm edge spacer lifts the temperature at the edge of the glass, which is where condensation starts. None of these can be added later, which is why an unusually low figure is worth reading for what the glass is rather than what it costs.

The internal reveal and the trades that follow

The glass is only half of what the room sees. The other half is the reveal, the lining between the ceiling and the frame, and it wants settling at quotation stage rather than at handover.

A square reveal is quicker to form and throws a hard rectangle of light on the floor. A splayed one, opening outwards towards the room, spreads light across the ceiling and makes the opening read as considerably larger. It costs a little more plastering time and nothing in glass. What matters for the figure in front of you is who is carrying it: whether the quotation includes forming and plastering the reveal, or leaves a plasterer to be found.

Notification, and why it belongs inside the price

Fitting a new rooflight or replacing an existing one is notifiable work under Building Regulations in England. It engages Part L for thermal performance, Part K where there is a risk of falling and Part B where the opening serves as a means of escape. There is a fee, and there is administration.

Sunspire handles the notification as part of the job and it sits inside the quoted figure. That matters more than the amount involved, because unnotified work surfaces years later during a sale, when a solicitor asks for a completion certificate that was never applied for.

What the fixed written price sets out

After the survey the range becomes one figure, in writing, itemised. It names the unit by manufacturer, model, external size, glazing specification with its U-value, and frame finish. It states what structural work is included and what calculation sits behind it. It says who forms the opening and who makes good the plaster. It confirms the notification is included. It puts a figure against access and against waste. And it sets out the programme in days.

That figure holds unless the scope changes. Changing the glass, moving the opening or adding an opener after agreement are changes, and they are re-priced openly rather than recovered somewhere quieter.

What can move a price after it is agreed

Two things, and being straight about both is easier than the alternative.

The first is a change you ask for: a different glass, a bigger unit, an opener added late. That is priced before it is done. The second is what the roof was hiding. Timber gone soft under an old kerb, a truss where a rafter was expected, or a fall that has flattened out over thirty years. A careful survey finds most of that in advance, but a roof is only fully honest once it is open. Where something does appear, it is shown to you, explained and priced before further work happens.

Decisions that cost nothing now and a great deal later

Three choices are free at design stage and expensive afterwards. Landing the opening on a standard glass size. Running a cable for a powered opener while the ceiling is open, since doing it later means lifting a finished ceiling. And ordering blind provision with the unit, because the side channels a rooflight blind runs in are part of the frame rather than an accessory.

For a first range, send the town, the covering, the orientation, the rough room size and the two photographs. If you are earlier than that, read the guides on sizing and specification first, because the decisions taken there set the figure.