Electric rooflights above a kitchen island

An island sits in the centre of the plan, and the centre of the plan is the part of a room that natural side light reaches last. Windows in the outside walls throw light a few metres in and then give up. In a knocked-through kitchen and dining space, which is most of what gets built onto the back of a house in south Essex, the middle of the floor is often the gloomiest patch in daylight and the most heavily lit by downlights after dark. A rooflight directly over the island answers both. It drops daylight straight down onto the worktop where the actual work happens, and it does it without a wall in the way to cast a shadow.

There is a practical reason the geometry works so well here. Light from a ceiling aperture arrives close to vertical, so it falls onto horizontal surfaces at nearly a right angle. A worktop is a horizontal surface. That means an island under a rooflight gets more usable light per square metre of glass than the same glass would deliver to a vertical wall, where much of the beam skims across the floor instead of landing on it. If you are chopping, reading a recipe or watching a hob, that overhead light is doing more work than a window of the same area ever could.

The island is also, usually, the room’s ventilation problem. Cooking puts heat, steam and cooking smells into the air right in the middle of the space. An extractor handles the worst of it, but an opening rooflight above the hob clears the rest through the highest point in the room, which is exactly where hot, moist air wants to go. Warm air rises and stratifies against the ceiling, so an opening at the top of the room pulls it out far faster than any window at head height on the wall. That is the case for opening glass over an island. The case for making it electric is that you can never reach it.

A manual rooflight opens in one of two ways. Either you turn a winder handle on a spindle, which needs the frame within arm’s reach, or you use a telescopic pole hooked into the sash from the floor. Over a wall-hugging worktop with a normal ceiling, a pole is workable. Over an island, it is not, for reasons that are worth spelling out because people only discover them after the ceiling is closed up.

First, the reach. Kitchen and dining extensions are frequently built with ceilings above the standard 2.4 metres, and a lantern or a deep pitched rooflight puts the opening sash higher still, often 3 metres or more above the floor. A pole that long is unwieldy, and finding the eye of the winder above your head while standing on a hard floor, in socks, is a two-handed fiddle you will do once and then never again.

Second, the position. The island is furniture you cannot move. To reach a rooflight directly above it with a pole you have to stand on the island itself or lean across the hob, and neither is something you will do to let a bit of steam out. So the honest outcome of a manual unit over an island is a rooflight that gets opened in April and closed in October, if that. It becomes a fixed light that happens to have a hinge in it. You have paid for ventilation you will not use.

Third, rain. A manual unit left open when a shower blows in over the estuary is a wet worktop. Southend weather turns quickly, and nobody is going to run for a pole every time the sky darkens. An electric opening rooflight solves all three at once. A wall switch, a handset or a phone opens and closes it on demand, a rain sensor shuts it for you when the first drops land, and the height of the thing stops mattering because your arm is no longer involved.

The moving part is a motorised actuator, a small electric ram that pushes the sash open and pulls it shut. Two designs cover almost everything you will be offered.

A chain actuator uses a rigid chain that is coiled inside the frame and pushed out to lever the sash open. It is compact, quiet and hidden in the frame, and it typically gives an opening of around 200 to 400mm, which is plenty for ventilation. A spindle or rack actuator uses a threaded rod and gives a longer, more powerful stroke, which is what you want on a large or heavy sash, or where the rooflight doubles as a means of smoke ventilation. For a domestic island the chain actuator is the usual and neatest answer. On a big lantern with a heavy glazed opening light, a spindle mechanism earns its place.

Control is where the choice really lies, and it is worth thinking about before the electrician is on site.

• Hard-wired wall switch. A rocker or keypad on the wall, wired back to the actuator. The most reliable option and the one that never needs a battery or a working phone. Site it by the door you use, not behind the island.
• Radio handset. A small remote paired to the unit, so you can open the glass from the sofa or the dining table. Convenient, and easy to lose down the side of a cushion.
• App and home automation. Many electric rooflights now tie into a phone app or a smart-home system, so the glass can open on a schedule, close at a set time, or respond to a temperature or humidity reading. Useful over a kitchen, where humidity climbs every time the kettle and the hob are going.
• Rain sensor. Not really optional over an island. A small sensor on the frame closes the rooflight automatically the moment it gets wet, so an open unit over your worktop is never a gamble against the forecast.

Sensors can go further than rain. Temperature and humidity sensors let a rooflight vent itself when a room gets hot or steamy and close again once it has cleared, which is close to ideal above a hob. If the island rooflight is one of several openings in the room, wiring them to a single controller lets the whole space vent together, pulling cool air in low and pushing hot air out high. That stack effect is the most efficient ventilation a room can have, and an island opening at the apex of it is the natural exhaust point.

Get the size and the placement right and the rooflight looks like it was always meant to be there. Get it wrong and it either lights the floor beside the island or overwhelms the room. A few rules of thumb hold up well.

Centre the rooflight on the island, not on the room. The two are often not the same point, because islands are usually pushed towards the kitchen end rather than sitting dead centre in a long open-plan space. The glass wants to be above the worktop it is lighting, so line it up on the island’s own centreline. If the island runs long and thin, a single square rooflight can look mean above it. Two units in a row, or a rectangular lantern, follow the shape of the furniture and light its whole length.

For area, a common and safe starting point is to make the glazed opening somewhere between the footprint of the island and half as much again. An island of 1.8 by 0.9 metres, roughly 1.6 square metres, sits happily under a rooflight of around 1.2 by 1.2 metres. Go much smaller and the pool of light is narrower than the worktop. Go much larger over a south-facing roof and you are back to the solar-gain problem this business exists to head off, which the next chapter deals with.

Mind the structure above the ceiling. The centre of the room is exactly where roof structure tends to be, so the position that suits the island may cross a rafter, a purlin or a ceiling binder. On a flat roof over an extension there is usually room to frame an opening wherever you want it. On a pitched roof, or where a steel already carries the span, the practical position can be constrained, and that is a survey question, not a showroom one. It is far cheaper to find the beam before the plasterboard goes up than after.

Here is the part most quotes leave off the page. A rooflight over an island is glass in the roof, and if that roof faces south, it is collecting solar energy as well as daylight. Southend faces south across the Thames Estuary, which is unusual for an English seaside settlement, and it means the rear extensions where islands live are frequently under south-facing or shallow south-pitched roofs with an open horizon and reflected light coming up off the water. On a clear afternoon that glass is not just bright, it is warm.

The physics is worth a moment because it decides the specification. A flat rooflight faces straight up, so at midsummer noon the sun strikes it far closer to square-on than it strikes a vertical window, and it collects roughly twice as much solar energy per square metre as a south-facing wall window would. It also sees the whole sky dome, so it picks up diffuse light even under bright cloud. And it is delivering all of that heat in at ceiling height, at the top of the room, where hot air already wants to sit. A kitchen is the worst room to add that to, because the hob and the oven are already pouring heat into the same space. An island directly beneath an uncontrolled south-facing rooflight becomes the hottest working surface in the house between about two and six on a July afternoon.

The number that governs this is the G-value of the glass, the share of the sun’s energy that passes through as heat. Clear double glazing sits around 0.60, so more than half the solar energy comes straight in. A good solar-control unit brings that down to around 0.28 while still letting most of the visible light through, so the worktop stays bright and stops cooking. On a south-facing island rooflight, the G-value matters more than the U-value that most quotes lead with, and choosing it well is the difference between a room you want to stand in and one you avoid in the summer. Our whole approach starts with which way the roof plane faces, then the glass, then the unit, and this is why. If your island rooflight is going into a south or west slope, this is worth reading in full on our page about solar-control glazing.

These are typical published figures for the glazing build-ups you are most likely to be offered on an electric rooflight, alongside the control features that suit an island. Exact values vary by manufacturer and by coating, so treat them as the shape of the market rather than a fixed spec.

Read the G-value column and the range from 0.60 down to 0.26 is the number that will decide how the room feels in August, on a quantity of heat that dwarfs anything the U-value controls in summer. Over a north-lit island the high-G clear unit is the right call, because there is no direct sun to manage and every scrap of daylight is worth having. Over a south or west island, the solar-control unit is the one that keeps the worktop usable.

On the control side, a sensible island specification tends to look like this:

• Chain actuator for a domestic-sized opening light, hidden in the frame and quiet in a room where people talk.
• Hard-wired wall switch by the main door as the primary control, so the glass works even if a handset is lost or a phone is flat.
• Rain sensor as standard, because the unit sits over an open worktop and nobody wants to bet on the weather.
• Optional temperature or humidity trigger if you want it to vent cooking heat and steam without anyone touching a switch.

One point the table does not carry: anything glazed overhead needs a laminated inner pane for safety, which Part K requires, and toughened outer panes are standard. The laminate interlayer also blocks almost all UV, so a solar-control island rooflight keeps the worktop and any timber below it from fading over the years.

An electric rooflight needs a power supply and a control run, and the time to plan both is before the ceiling is boarded. The actuator is low-voltage, driven from a transformer or control unit that a qualified electrician wires in, and the cable route from the frame to the switch position wants to be agreed while the void is still open. Chasing a cable to a wall switch after the plaster is on is disruptive and avoidable. If the rooflight is going to talk to a home-automation system or a group controller, that gets specified at the same time.

New and enlarged rooflights are notifiable under Building Regulations. Part L covers the thermal performance, which is where the U-value has to meet the limit for the work, and Part K covers the safety glazing overhead. We make the Building Control notification to Southend-on-Sea City Council, or the relevant local authority for your address, as part of the installation, so the glazing and the opening mechanism stand up on paper as well as in the room.

Rooflights are generally permitted development on a house where they project no more than 150mm beyond the roof plane and sit below the ridge, so most island rooflights on an ordinary house do not need planning permission. The exceptions matter locally. Flats and maisonettes, listed buildings and conservation areas are treated differently, and the Leigh Cliff and Leigh conservation areas carry an Article 4 Direction that removes permitted-development rights for changes to roofing and windows, so a planning application is needed there where it usually would not be. This is general guidance and the right move is always to check with the local authority for your own address before ordering glass. It is one of the things we confirm at survey.

An electric rooflight over an existing island, where the roof is already the right type, is not a long job on site. The opening is formed and trimmed, an insulated and weathertight upstand or kerb is built up from the roof to carry the frame, the unit is set and sealed, and the actuator is wired and commissioned so the glass opens, closes and responds to its rain sensor before anyone leaves. On a new extension the rooflight is designed into the roof from the start, which is always the cleaner outcome, because the structure, the cable route and the switch position are all settled on paper.

If you are getting quotes, a short list of questions sorts a considered specification from a guessed one.

1. “Which way does this roof plane face?” Orientation comes before the product, not after it. If the answer is vague over a south-facing island, the glass choice behind it is probably vague too.
2. “What is the G-value of the glass?” A number should come back. “Energy efficient” and “A-rated” describe winter performance and say nothing about the summer heat over your worktop.
3. “Chain or spindle actuator, and how far does it open?” A chain unit opening 200 to 400mm suits most island rooflights. A heavy or very large sash may want a spindle.
4. “Is there a rain sensor, and where does the switch go?” Over an island the rain sensor is not optional, and the switch belongs by the door, not somewhere you have to walk round the island to reach.
5. “Who notifies Building Control?” New and enlarged rooflights are notifiable. We make that notification as part of the job.

The full picture on mechanisms, controls and wiring lives on our electric skylight installation page, and if you want the glass matched to your own roof, our guidance on choosing a roof lantern and on flat-roof skylights covers the two roof types most islands sit under. We have been installing skylights and rooflights across south Essex for over fifteen years, every job backed by a ten-year workmanship guarantee, and the survey starts with the compass. When you are ready, ask us for a specification with the G-value and the opening mechanism written down for your own island, not a single figure waved across the whole roof.