A manual rooflight is glass, a frame and a handle. An electric one adds a motor, a way to feed it, a control and often a sensor, and every one of those parts has to be bought, wired, tested and made good afterwards. That is why two electric units of the same glass size can come to quite different totals on a written quote.
For what the products are and how they work, start at our electric opening rooflights page. For the other products we fit, the costs page shows how each quote is built.
What the motor adds to a manual unit
Strip an electric rooflight down and you find the same glass as a manual one. The extra is a short list of parts. An actuator pushes the sash or lid open and draws it shut. A controller tells the actuator what to do. A power source feeds both. A sensor, if you want one, shuts the glass when rain lands on it.
Each part brings labour as well as a price. The actuator has to be fitted into the frame, so the frame is often specified as an electric model from the start. The controller needs a home near the opening. The power feed needs a route. The sensor is fixed outside, where it gets wet, and has to be sealed.
A manual unit with a pole
The comparison to make is with a manual window on the same roof. The glass, the frame and the flashings are priced the same way for both. What the electric version adds is the group of lines in the table, and the more of them you choose, the more the quote moves.
| Part | What it does | What moves its price |
|---|---|---|
| Actuator | Pushes the sash or lid open and closes it | Weight and size of the sash, and the number of units |
| Controller or driver | Takes the signal and drives the motor | Whether one unit or several share a keypad |
| Power supply | Feeds the motor at the right voltage | Mains, low-voltage transformer or a solar panel |
| Rain sensor | Closes the glass when it gets wet | Fitted to the unit or added to a window already in the roof |
| Wall switch or remote | Lets you operate the glass from the room | Switch, handheld remote or keypad |
Mains, low voltage or solar: how the feed shapes the figure
Three ways of powering the motor lead to three different sets of costs. A mains unit needs a fused connection and cable from the house wiring. A low-voltage unit runs from a transformer, which sits in the loft, a cupboard or the void above the ceiling, with a thinner cable running from it to the motor. A solar unit carries a small panel and a battery on the glass, so no cable crosses the ceiling at all.
Solar sounds like the cheaper route, and in a spot with no easy cable path it often removes the biggest line on the quote. It relies on light reaching the panel, so the aspect and shading of the roof come into the decision. A north-facing slope under a tall tree is a poor home for it. Our guide to solar powered skylights explains where it works.
Why the transformer needs a place
A low-voltage system needs room for its transformer, and the room has to be reachable for servicing. A loft with a hatch makes that easy. A flat roof with a shallow build-up above a kitchen ceiling is harder, and the quote may include a recessed box in the wall or a joiner's detail in the ceiling.
The long version of the options sits in the guide to powering an electric rooflight.
Ask which feed is priced
Mains, low voltage and solar are three different quotes for the same glass. Two figures can only be compared once both name the feed.
The cable route, and who installs it
On a bungalow with a plastered hall ceiling, the roof window may sit above a boarded ceiling with insulation laid over it, and the switch belongs by the front door. The cable has to get from one to the other without scarring the finish. In a loft study where the slope is open behind a lining, it runs along a rafter and drops behind the plasterboard.
The route becomes a separate line for that reason. A short run through an accessible void is a small item. A path behind finished plaster, round a chimney breast or through a flat roof build-up can take longer than fitting the glass. Where the room is still being built, the electrician can lay the conduit before the ceiling closes, and that saves the most.
The electrician is a line of its own
Fixed wiring in a home is regulated separately from the roof opening, and has to be installed by someone able to do that work to the standard. We agree who carries it out before the quote is fixed, and it appears as its own line so you can see what it costs. Our short answer on hiring an electrician for an electric rooflight covers the split of work.
Switch position is a cost choice too. A switch beside the bed, the door or the island dictates the cable length. Moving it after the plaster is dry costs far more than choosing it first, so we mark the spot with you at the survey.
What the cable route changes
- Length of runFrom the motor to the supply and to the switch.
- Finished or open surfacesA void behind the lining is cheaper to cross than plaster.
- Sealing through the roofA flat roof build-up needs the cable to pass through watertight.
- Who does the electricsA named installer and a written scope.
Roof form, glass and the energy limit
The roof sets the unit before the motor is chosen. A pitched slope takes a roof window, which sits in the plane of the roof, and for an existing home a new or replacement roof window must meet 1.4 W/m²K, or Window Energy Rating band B at least. A flat roof takes a rooflight on a kerb or a lantern with vents, and that must meet 2.2 W/m²K. A glazed unit that opens has a sealed joint between sash and frame, so its specification matters for the room's comfort as much as for the paperwork.
Beyond the limit, glass choices add to the quote the same way they do for fixed units. Laminated inner panes suit a bedroom or a bathroom. Solar control coatings help under a south-facing slope. Obscured glass suits an en suite. Each is one line, and none is compulsory.
Standard ranges and made-to-measure lids
Where an opening matches a manufacturer's size, the unit comes from the range with a short wait. A flat-roof opening that does not match is made to measure, and the motor is specified with it. A bigger lid is heavier, so the actuator that lifts it is larger too. Both sit on the quote against the lid.
Words on an electric rooflight quote
- Actuator
- The small motor that pushes the sash or lid open and pulls it closed.
- Rain sensor
- A detector on the outside of the unit that sends the close signal when it gets wet.
- Window Energy Rating
- A rating band for the whole window; band B is the minimum alternative to the 1.4 W/m²K limit for a new or replacement roof window.
- Kerb
- The upstand a rooflight sits on over a flat roof.
A heavier lid needs a bigger actuator, and the quote names both
Motorising a window already in the roof
If the opening exists, the job is usually a swap. The old unit comes out, an electric one goes into the same space, and the lining is refitted with the cable behind it. Our guide on swapping an old VELUX window shows how that works for a pitched roof.
A new opening costs more again. It adds structure around the hole, the flashing, the lining and, on a house, the planning question. For a roof window on a house, the conditions include keeping the frame within 150 mm of the plane of the original roof slope and the rule for side slopes; see skylight planning permission for the rest. A lantern on a flat roof normally stands more than 150 mm proud, so a flat-roof lantern with vents normally needs planning permission unless the council confirms otherwise.
Fitting a vent to a lantern
Some owners want opening vents in a lantern instead of a separate rooflight. A lantern with vents still lights the middle of the room, and the vents can be motorised. The extra for each vent is the motor, the controls and the cable, added to the lantern itself, whose own cost drivers are in our guide to roof lantern cost.
Paperwork, and what a clear quote names
Cutting a fresh opening through the roof structure counts as building work, which puts a Building Control fee on the quote. We handle the Building Control notification where the work is notifiable, and the council or a registered building control approver inspects it. Electrical work has its own paperwork alongside: the person who connects the supply provides the electrical certificate for their part, and the roof opening has its own paperwork.
When you compare two quotes for an electric unit, line them up against the steps below. A figure that leaves out the electrics or the controls can look cheaper until the missing lines are added back.
Our survey is free, and the quote that follows names every line. The work carries a 10-year workmanship guarantee in writing. To start, WhatsApp 07880 284133 with a photo of the ceiling and the slope above it, or book a free survey. For the fuller picture of the rules, skylights and Building Regulations goes through each step.
Lines to match across two quotes
- The unit Size, roof form, frame and glass, with the motor model named.
- Power Mains, low voltage or solar, and where the supply or transformer sits.
- Controls and sensor Switch, remote or keypad, and the rain sensor if one is wanted.
- Cable and electrician The route, and who carries out the fixed wiring.
- Roof, finishing and paperwork Flashing, lining, plaster, and the Building Control fee.
