How Much Does It Cost to Replace a Skylight?

Rooflight replacement cost begins with what you are replacing. A pitched roof window in a slate or tiled slope is a factory-made unit that comes with its own flashing kit. On a flat roof the rooflight stands on a kerb, and it is frequently made to order. A roof lantern has bars, a frame and a lot of glass, and it is built to suit one opening. A sun tunnel consists of a roof dome, a light tube and a diffuser in the ceiling. Each has a different spread of materials and a different amount of labour.

Size sits within that. A larger unit uses more glass, more frame, more flashing and more lifting, and the cost does not rise in a straight line.

The make and range matter as well. A branded roof window such as a VELUX comes at one level, an equivalent from another maker at another, and a bespoke aluminium rooflight at another again. Our quote is for the unit we recommend on your roof, with the reason given, which lets you compare like with like against any other quote.

Replacing like for like keeps the work simple. The new unit goes into the opening the old one left, with no new timber to cut and no new hole in the ceiling. That is almost always the cheaper route.

A larger opening adds labour and materials that never appear in the unit price. A rafter or joist is cut and trimmed, the roof covering is opened up wider, and the lining inside is bigger. On a flat roof, a longer span may need heavier timber, and a new kerb is built to match. In England this kind of structural change is also dealt with under the Building Regulations, which we cover in rooflights and Building Regulations.

• Same opening: the simplest and usually lowest-cost route
• Larger opening: structural work and more making good
• Smaller or moved: the old hole has to be filled in
• Different make: sizes may not line up with the old frame

Glazing is where a good deal of the variation sits. A standard double-glazed unit with a laminated inner pane is the baseline. Triple glazing, solar control coatings, self-cleaning outer glass and acoustic panes all raise the price of the unit. Whether the extra is worth it on your roof is the subject of double or triple glazed rooflights.

Opening gear is the next step up. A fixed rooflight is the simplest. A manual opening one adds hinges and a handle. An electric or solar-powered one adds a motor, a rain sensor, a controller and, for mains versions, a cable run and a switch. So turning a fixed rooflight into one that opens involves wiring as well as the unit, and the swap from fixed to opening is covered in its own answer.

Finish and extras follow. A frame colour other than white, a bespoke bar pattern on a lantern, a blind built into the frame, or an external awning each carry their own cost. None of them is essential, but they are easy to add at the order stage and awkward to add later.

Access is a cost that people forget until they see it on a quote. On a single-storey rear extension, a ladder or low platform is often enough to reach the roof. A three-storey Victorian terrace, or a roof set well back from where a van can park, needs scaffold or a tower. A heavy lantern may need a lifting plan. Scaffold takes time to put up and take down, and it is charged accordingly.

The roof around the opening comes next. If the old frame has been leaking, the timber beneath may be soft and need replacing, and the slates, tiles or membrane around it may need work before the new flashing will sit properly. A new kerb or upstand, with fresh insulation and a dressed waterproof membrane, is a bigger item than a unit on its own. We cannot know that until the old frame is lifted, which is why the survey looks at the signs, and why we tell you at once if the opening shows something unexpected.

Inside, the lining, plaster and any redecoration add to the work. A like-for-like swap often leaves the lining untouched. A larger opening means new plasterboard, skim and a clean join with the ceiling. If you want the splay reshaped to throw more light into the room, that is extra but worth doing at this stage.

Then there are the Building Control notification and, where the work is structural, any engineer's detail. Where the work is notifiable, we make the notification ourselves and the fixed written quote says so. Replacing a rooflight, step by step shows where each of these falls in the job.

The process is short. We visit, look at the unit and the roof, measure the opening, and talk through the choices. A fixed written quote follows, naming the unit, its size, the glazing, the access arrangements and the finish. If something changes after you accept, such as a different glazing choice, the change is agreed in writing before the work goes ahead. The workmanship guarantee runs to ten years and goes on paper as well.

How we price work across all ten services is on the costs page. Booking the survey on your own roof takes a free quote request or a WhatsApp message.