Can rooflights be opened electrically?
Yes. Every rooflight type that opens at all is available with a motor driving the pane, and on most current ranges the motorised version is a catalogue item rather than a special. Roof windows in a tiled slope, hinged units on a flat roof kerb, sliding panels over a kitchen and the ridge vent in a lantern all come with an actuator option.
What decides whether you can have one is rarely the product. It is whether a cable can reach the head of the unit, whether the sash is within the weight the drive is rated for, and whether the roof plane suits an opening pane at all. The wider subject sits on electric rooflight installation.
What the word electric covers on a rooflight
An electric rooflight is a fixed rooflight with three additions: an actuator that pushes and pulls the opening pane, a control unit that feeds it and receives the signal, and something to press. The glass, the frame, the flashing kit and the kerb are the same components as the fixed version of the same model.
That is worth knowing because it separates the two halves of the decision. The weathering performance of the unit is a property of the frame and the perimeter detailing. The convenience is a property of the motor. Adding one does not compromise the other, provided the sash still closes home onto its gasket with full force every cycle.
Which rooflight types take a motor
The four common domestic formats all have motorised versions, and each opens in its own way.
- Roof windows in a pitched slope, top hung or centre pivot, with the actuator concealed in the head of the sash.
- Hinged flat rooflights sitting on a kerb, lifting on one edge, usually driven from inside the frame or from a bracket on the kerb.
- Sliding flat panels, where the moving pane travels sideways over a fixed light on a track rather than lifting into the wind.
- Roof lantern ridge vents, a small opening pane set into one plane or at the ridge, driven by a short stroke actuator.
Sun tunnels are the exception, because a reflective duct has no opening pane. Where a room needs both daylight and air and the ceiling has no roofline of its own, that is two separate pieces of work rather than one.
Factory-built motorised units against drives added on site
There are two ways a rooflight ends up motorised, and they are not equivalent.
A factory-built electric unit arrives with the actuator already mounted inside the frame, wired to a terminal at the head, with the geometry set and the limits pre-configured. The mechanism is concealed and the manufacturer stands behind the whole assembly, weathering included.
A drive added on site is bracketed to an existing sash, usually with a visible casing along the head or the side. Where the kit is the manufacturer’s own for that exact model, it works well. Where somebody improvises a bracket onto a frame that was never designed for the load, the fixings end up carrying a force the profile was not made to take.
Opening angle, and what each range of movement is for
How far a motorised pane travels is set by the stroke of the actuator, and it is the specification most often left vague at order.
A short stroke gives a gap of perhaps ten degrees. That is trickle and background ventilation, useful for shifting the warm layer at ceiling level over a whole evening. A long stroke on the same sash reaches twenty degrees or more, which is a purge: enough free area to clear cooking air from a kitchen in a few minutes rather than an hour.
What has to be true of the roof first
Some roofs will not take an opening rooflight at all, motorised or otherwise, and that answer comes before any product conversation.
A pitched slope has a minimum pitch below which the manufacturer will not warrant an opening sash, because a shallow angle leaves water sitting on the joint rather than running off it. On a flat roof the kerb has to be square and level along the hinge line, because a sash meeting its gasket harder on one side than the other will not seal. And on a trussed roof across the newer Essex estates at Great Notley or South Woodham Ferrers, the width of any roof window is capped by the truss spacing, motor or no motor.
Getting power to the head of the unit
Domestic actuators almost all run at 24V direct current. The mains stops at a transformer or a control unit sited in a cupboard or a roof void, and a low voltage cable carries on from there to the terminal at the head of the rooflight.
That cable is the whole difficulty. On an open ceiling it takes minutes to run. On a finished plastered ceiling, particularly a warm deck flat roof with no void in it, there is nowhere for it to go without lifting work that was already paid for. Where the moment has passed, a solar powered unit carries its own panel and cell and needs no cable at all.
Controls, and how many a unit ends up with
A motorised rooflight needs at least one way of being told what to do. A hard-wired wall plate is the most dependable and puts a switch on a wall somebody chose carefully. A radio handset removes the plate and creates the question of where the handset lives. Wireless wall plates sit between the two: they look like a switch, they stick where they are wanted, and the cell in them lasts years.
Most units end up with a wired plate and something wireless alongside it. Where a rain sensor is fitted, it overrides all of them and drives the pane shut on its own, which is covered on whether electric rooflights close automatically in rain.
The decisions worth settling before ordering
Four answers turn this from a preference into a specification. How high above the finished floor the glass will sit, because reach is what decides whether a manual unit gets used or becomes an ornament. What the sash will weigh once the glazing is settled, because the drive is rated for a mass and not for a size.
Then the cable route, and whether it is still open. And finally the exposure of the roof, because a lifted pane on the estuary fringe around Maldon or Burnham presents a sail to wind coming across a flat surface, and that governs both the stroke and the drive. Sunspire settles those at survey and turns a range by email into a fixed written figure.
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