Electric and opening rooflight installation in Exeter

An opening rooflight is any roof glazing that can be moved to let air in. The sash swings up on hinges at the top, pivots about its middle, or lifts bodily on arms. Which of those it does depends on the product, the roof and the pitch, and we compare them in our guide to top-hung and centre-pivot roof windows.

What makes it electric is the way it moves. A small motor, built into the frame or fixed alongside it, pushes the sash open and pulls it shut. You press a button on a wall panel or a handset, or the unit answers a sensor, and the window moves without anyone reaching up to it. The glass, the frame and the flashing are the same as on a manual unit. The difference is in the motor, the controller and the cable behind the plaster.

There are three ways to power one. A mains unit runs from a transformer wired to the house supply. A solar unit carries a small photovoltaic cell and a battery in the frame, so no cable is needed. A battery unit uses a rechargeable pack that you top up from time to time. Each has a place, and which one suits your room comes down to reach and to the ceiling.

Under all of this sits one fixed truth: the window is only as good as its fit in the roof. A motor does not cure a skewed frame or a weak flashing. So the roof work is done to the same standard whether the unit opens by hand or by motor, and the list of parts below is the vocabulary you will meet on a quote.

The choice is mostly about reach and about the cable. A manual unit is opened with a handle at the bottom of the sash, or on a pole with a hook. It is simple, costs least and has nothing to go wrong. It suits a window you can reach comfortably from the floor, in a room where you are happy to open it yourself and close it when you go out. We weigh up the two in electric or manual opening rooflights.

An electric unit is the answer where the window is out of reach, where several windows should move together, or where you want it to react to the weather without you. Then the question becomes how the power arrives.

Mains electric

A transformer, usually near the unit or in a nearby cupboard, steps the supply down to a low voltage for the motor. It is steady and has no battery to think about. The price is a cable run from a spur or a nearby circuit to the window, which has to be planned and hidden. In a loft room that run is usually easy, and in a finished kitchen ceiling it needs thought.

Solar

A small solar cell on the outside of the frame trickle-charges a battery in the frame, and the window runs from that. No cable is needed, so it suits a ceiling that cannot easily be opened up for wiring. Devon light is enough for it, but the cell wants to face a reasonably open sky, and it works best in unshaded positions. Our guide to solar-powered rooflights and windows explains where it works and where it does not.

Battery or remote

A rechargeable pack that sits in the frame or alongside it runs the motor, and you recharge it every so often. It is a middle route where there is no easy cable and little sun on the glass.

Controls follow the power. A wall switch beside the door, a handset kept in a drawer, a small keypad on the landing and an app on your phone can all operate a unit, and many systems let you group several windows so that one press moves them together. The wiring and the control system are tied to the brand, so we agree the make at survey before the quote is written. Our answers on linking electric rooflights to a smart home system and whether electric rooflights need an electrician cover the two questions people ask first.

Building Regulations treat an opening rooflight as a ventilation device, and a good one can do real work. Approved Document F, which deals with ventilation, recognises openable windows as a route to purge ventilation, the occasional, fast air change you need after cooking, bathing or decorating. An opening roof window or a flat rooflight in the right place can contribute to that, alongside the background ventilation the rest of the home already has.

Cooling is a different job, and the physics helps. Warm air rises, so a window high in the roof lets it escape, and a window lower in the house lets cooler replacement air in. With two openings at different heights the air moves on its own, which is called stack ventilation. A rooflight at the top of a stairwell and a window at the bottom can pull a gentle draught through the whole house on a summer evening without a fan. Our guide to opening rooflights for ventilation and cooling explains how to arrange it.

A motor makes this work better than a pole. You can open a high unit fully at night, set it to a small gap during the day, and close it all at once when you leave. In a hot loft bedroom that routine can take the edge off a July night more effectively than a single window opened by hand, because the vent is in the right place and gets used.

It pays to think about where the openings sit before the glass is ordered. A rooflight on the shady side of the roof will draw more gently than one in full sun, but it also lets in less solar heat. A unit at the ridge end of the room works best for air, and a unit near a bed or desk needs a draught that does not blow papers about. We settle these questions at survey, with the roof and the room in front of us.

Opening glass cannot cure a room that is hot because of the glass itself. If the sun is the cause, solar control glass and a blind do more than ventilation, and our page on energy efficient rooflights covers what the glass can do. For small rooms a simple opening unit with a good flyscreen is often all it takes, and we answer whether opening rooflights have insect screens separately.

Planning and Building Regulations are judged independently. On a house, rooflights normally come under Class C of Part 1, Schedule 2 of the General Permitted Development Order, as long as they stand no more than 150mm clear of the roof slope and stay below the high point of the roof. A roof window that opens swings its sash outward, but the frame and glass in the closed position are what the rule measures.

Side-facing rooflights need extra care. Under the same rules, a side-facing unit must have obscure glass and stay fixed unless its openable part is over 1.7m above the floor. That catches a loft room with a window in a side slope, so check it before the product is chosen. A flat or maisonette has no householder permitted development rights, which makes a conversation with the council planning team the first step there.

Class C applies in conservation areas, though an Article 4 direction may take it away. Any external change to a listed home calls for listed building consent first. Dartmoor and Exmoor are national parks, which is Article 2(3) land, and some rights are restricted there. Where any of this varies by property, we ask you to confirm with the council planning team, and we help you do it. The planning side of older homes is in whether conservation rooflights need planning permission.

Under Building Regulations, forming a new opening where no window existed counts as building work. Altering rafters is structural, and the new window must satisfy Part L, the conservation of fuel and power. Taking out a complete rooflight and fitting another, frame and glass together, is notifiable too, because a window counts as a controlled fitting. Changing only the glazed unit inside a frame that stays does not need notifying. Where a job is notifiable, we make the Building Control notification.

The electrics bring a third point. New electrical work in a home is covered by Part P of the Building Regulations, which deals with electrical safety, and the supply to a motor is part of that. We say at survey who does the wiring and how it is certified. A loft room also raises Part B, the fire regulation, because a roof window can serve as an escape window if it meets the size and position rules in Approved Document B. Not every opening rooflight qualifies, and we use cautious wording about it. Our answer on whether a roof window can be a fire escape sets out the rules.

We price every unit from a survey, because the same window can cost very different amounts on two roofs. The written quote breaks the job down, and our costs page shows how a typical quote is built up, with general market ranges for each type of rooflight.

The unit comes first. An electric roof window costs more than a manual one of the same size, and a solar or battery version costs more again. The glass specification, the frame finish and the brand all count. A flat rooflight that opens needs an actuator and a hinged frame, and a big one costs more than a small one.

The inside of the job matters here as well.

The roof and the access come next. A new opening in a pitched roof needs the rafters trimmed and possibly an engineer's calculation. A flat roof may need a new upstand. Scaffolding or a careful lift may be needed, and the covering around the opening may need renewing to take the new flashing.

The electrics are their own line. A cable run through a loft is simple, while one through a finished ceiling takes more time. A single mains window needs a transformer, a switch and a supply. A group of windows on one controller needs more cable and a more careful set-up. Rain sensors, handsets, wall panels and any smart home link all sit on the quote as items.

The inside of the job matters here as well. A motor housing, a splayed reveal, lime plaster in an older house and an electric blind all take time. Building Control fees and any electrician's certificate sit on the quote too. Because the finish schedule puts the reveal, the plaster and the decoration in writing, you can compare it line by line with another quote. The 10-year workmanship guarantee described on our guarantee page covers our work on the roof and in the room alike.

It is a single page, written for your room alone.

It depends on the type. A top-hung roof window opens to a modest angle, a centre-pivot unit rotates much further, and a hinged flat rooflight lifts on an actuator to a set angle. The maker's range decides the limit, and the swing affects the lining and any blind. We explain it in how far opening rooflights open, and note the opening distance on your quote.