Do electric rooflights close when it rains?

On those VELUX windows, the rain sensor has the motor bring the sash down once rain arrives. You open the rooflight for air and leave for work, and the window closes without anyone at home. Without a sensor, an electric unit does what the switch or remote tells it, and nothing more.

That gap is why the question gets asked in Swansea. A window left open on a mild morning can meet a squall by noon, and over a bed, a stair or a bathroom floor the difference between shut and open counts.

Manufacturers differ on what comes with a model, so the sensor is a point to settle for each unit. The built-in sensor comes from VELUX, on the roof windows it sells with solar or electric operation. On a flat-roof rooflight, or a unit from another maker, ask whether the sensor is offered and whether it goes in the specification. Our rain sensor guide covers the parts and how they sit on the frame.

Think of the rooms where a window is left open and forgotten. A loft bedroom under the slope takes wind-driven rain straight onto the glass, and a duvet below it is only a few feet from the opening. A bathroom roof window is opened for steam, then left. A landing or stairwell unit is out of reach, so nobody pulls it shut by hand when the sky darkens.

In each of those, a VELUX sensor takes over a job that would otherwise depend on someone being home and looking up.

A motor and a sensor both need a supply. A mains unit takes it by cable, and the switch is placed in the room. VELUX sells solar-powered versions that need no mains feed. The wiring is worked out at the survey, since the cable route and the switch position affect how the finished ceiling looks. The wiring guide for electric units shows the choices.

Once the window is shut, it behaves like any other glass in the roof: rain crosses it and runs off. Glass carries the sound of a downpour into the room, and VELUX offers glazing options such as rain noise reduction to take the edge off it. They depend on the window and the variant, so they are a survey topic, along with how the flashing is matched to your roof covering.

A sash that closes on rain also leaves the room with the vent shut. If the room fogs, the answer lies in how it is aired, and the survey looks at that as well.

An opening window in a loft bedroom can matter for more than air. Escape is a separate question from air: climbing out through a roof window depends on its having been sized and sited as an escape window. The Welsh guidance sets the clear opening at 0.33 m² or more, at least 450 mm in height and in width, with its bottom edge no higher than 1,100 mm from the floor. For a roof window the bottom edge may be 600 mm up. The wider the sash opens on its motor, the more the escape question is worth raising early. If your window is meant to serve as a way out, say so at the survey so the unit is chosen for it.

A new rooflight generally needs Building Regulations approval in Wales, and a roof window going into an existing home should reach 1.4 W/m²K or Window Energy Rating band B. Where the work is notifiable, we handle the Building Regulations notification with local authority building control or a registered building control approver. On protected land, such as a conservation area, a National Park, the Gower AONB or a World Heritage Site, a new rooflight in the slope needs a planning application; see the Wales planning guide for skylights.

The range is on the electric opening rooflights page, and the cost of an electric rooflight is covered separately. For the free survey, phone 01792 929062 or use the booking form.