The short answer
Compared with an ordinary roof window of identical opening size, a conservation rooflight costs more, because the frame is slimmer, the glass unit is made to a heritage specification and the unit is usually made to order. Size, frame material, glazing bar, glass and the roof covering around it move the price, and your quote prices each one.
Why a heritage rooflight costs more than a standard one
A standard roof window is made in volume, in a set range of sizes, with a deep frame that stands above the roof covering. A conservation rooflight sits almost flush with the tiles or slate and has a thin frame, often with a central glazing bar, so the maker builds it to a tighter finish and often to your measurements. Fewer are made, and each one takes more handling, which is where much of the extra cost comes from.
The skylight you choose for a period roof also tends to be the one that stays, so the price is spread over a long life. The sections below take the parts of a quote one at a time, so you can see what each one adds.
Size and the frame material
Size has the plainest effect: a larger opening needs more glass, a stronger frame and more roof work, so it costs more. A made-to-measure unit costs more than one of the maker's stock sizes, though on an older roof with irregular rafter spacing the stock size may not fit without extra carpentry, and that carpentry is a cost too.
Frame material matters next. A steel frame gives the slimmest sightlines and the closest look to a Victorian factory or cottage rooflight, and it usually costs most. An aluminium frame costs less, comes in more colours and can be slim enough for most heritage roofs. A painted timber frame suits some period interiors and sits somewhere between them, depending on the maker. Our conservation rooflight guide sets the frame types side by side.
| Item | Usually lower | Usually higher |
|---|---|---|
| Frame | Aluminium | Steel, hand finished |
| Size | Maker's stock size | Made to measure |
| Glazing bar | Applied bar on the glass | Bar built into the frame |
| Glass | Standard double glazing | Low iron or laminated glass |
| Opening | Fixed | Hand or electric opening |
The glazing bar and the glass
A central bar is part of the heritage look. A bar built into the frame costs more than a bar applied to the face of the glass, and the difference in how each looks from below is covered by our answer on why conservation rooflights have a glazing bar.
Double glazing is the usual starting point and our answer on double glazed conservation rooflights covers how it fits a slim frame. Extra features add to the figure: laminated glass, a solar control coating, or a self-cleaning outer pane. Low iron glass, which looks clearer at the edge, can cost more again.
Opening versions cost more than fixed ones. A rooflight that opens lets fresh air into a loft room in summer, so for some rooms the opening version earns its price in use.
Roof covering, access and consents
On a tiled or slate roof the covering is lifted around the opening and relaid up to the new unit. Reclaimed slate and handmade clay tiles take longer to lift and are easier to break than modern tiles, so the work around them costs more. Steep pitches, high eaves and restricted access add scaffold and labour, and a rooflight wider than the gap between rafters needs trimming.
Consents come before the build. A listed property needs listed building consent in addition, and our answer on consent for a rooflight on a listed building explains what the council looks at. Sitting in a conservation area does not by itself remove permitted development, although permitted development can be withdrawn through an Article 4 direction or by a planning condition, so the address is examined by us and the council decides. Our conservation area guide and rooflight planning guide set out the conditions. The council fee, and drawings or a heritage statement if the council asks for them, are separate from the cost of the unit.
Where the whole rooflight comes out, frame and glass together, the Building Regulations make it notifiable. Cutting into the roof for a new opening is building work as well. Building Control is notified by us on any notifiable job, and the quote lists that as a line of its own.
What a quote should show
Two conservation rooflights of the same size can sit a long way apart in price once frame, bar, glass and roof work are counted. A number offered before anyone has looked at the roof would be a guess, hence the free survey, followed by a written quote that itemises each part.
- Unit, glass and bar priced as separate lines
- Roof covering and carpentry shown on their own
- Maker's typical lead time stated for each option
Each quote puts several suitable options next to one another, using different makers when the roof lets us, so a steel frame can be read against an aluminium one on identical rows. To see real numbers for your slope, book a free survey and we will price the rooflights that suit your roof.
Related questions
Is a steel conservation rooflight worth the extra over aluminium?
Steel gives the thinnest frame and the most traditional look, which matters on a listed or very visible roof. Aluminium is a sound choice wherever a slightly wider frame will pass unnoticed, and both materials get priced if each suits the opening.
Does the quote include the council fee for consent?
The council charges its own fee, so it is shown apart from our price. We examine the permission position for your address, then tell you which details the council tends to raise on a roof like yours.
Can I save money by choosing a stock size?
A stock size usually costs less than a made-to-measure unit, and it often arrives sooner. It only helps if the opening can be cut to suit the rafters, so we measure on site before we advise.
Why does a rooflight on a slate roof cost more than on a modern tile roof?
Slate is thinner and more brittle to lift, and old slate is often reused, so the roofer works slowly and keeps spares. That extra labour is itemised on its own line in the quote.