Do rooflights need blinds?

Start with where the slope points

The compass tells you more about whether a blind is needed than the size of the unit does. A north-facing slope takes no direct sun for most of the year. The light it delivers is even, cool and steady from morning to evening, which is why a rooflight over a north-facing stairwell or landing frequently needs nothing behind it at all.

East is briefly bright. The sun arrives low, lights the room early and has moved off the glass by the middle of the morning, so the effect is short and often welcome in a kitchen.

South carries sun across it through the middle of the day, high in summer and low in winter. Glass laid at a roof pitch meets that high summer sun far more squarely than a vertical window does, and that is where the heat comes from.

West is the one owners underestimate. Late afternoon sun sits low and comes in almost along the room rather than down onto the floor, at the end of a day when the house has already warmed through. A west-facing rooflight over a bedroom is the standard case for shading.

A landing is not a bedroom

The second question is what happens in the room. Circulation space is forgiving. A hall, a landing, a stairwell or a shower room is occupied briefly, nobody is trying to sleep or read a screen in it, and a bright band of sun crossing the wall for an hour is a pleasant thing rather than a problem. Rooflights in those positions are routinely fitted with nothing on them and the owner never thinks about it again.

Rooms people sit still in are different. A bedroom has to be dark at times when the sky is not. A home office or a room with a television has a screen in it, and glare on a screen is not a temperature question at all: it is a bright source sitting in your field of view and washing out what you are trying to look at.

So the useful question is not whether rooflights need blinds. It is what this particular room is for, and where this particular slope faces.

Stopping heat before the glass

This part is worth being straight about. External shading and an internal blind are not two versions of the same product. They act at different points, and one is considerably better at controlling heat.

An external awning or shutter sits on top of the glass and intercepts sunlight before it enters the building. The energy is absorbed and shed outside, into open air. An internal blind sits behind the glass, so the sunlight has already passed through and become heat inside the room. The blind then absorbs it and radiates it back into the same space. It manages the brightness well. It manages the temperature much less well.

That does not make internal blinds pointless. Glare, privacy and blackout are real requirements and an internal blind answers all three. But where the actual complaint is that the room gets hot, an internal blind on its own will disappoint, and it is better to know that before ordering than afterwards.

Blackout is a separate requirement

Glare control and blackout are discussed as though they were one specification. They are not, and confusing them is the commonest source of disappointment with a bedroom rooflight.

A pleated or translucent blind diffuses light. It softens a hard beam, takes the edge off a bright sky and makes a screen readable. Light still passes through it, which is usually the point. In a bedroom that is not enough. A room lit from above is light early in summer, and overhead light is harder to sleep through than light from a window in a wall, because there is nowhere to turn away from it.

Blackout means an opaque fabric running in side channels, so light is stopped at the edges as well as across the face. Without those channels a line of daylight runs down each side of the blind and the room is not dark. If somebody is going to sleep under the unit, say so while the rooflight is being specified and let the blind be chosen for that job rather than for glare.

Ordered with the unit, not afterwards

Blinds are normally ordered alongside the rooflight, and the reason is practical rather than commercial. Manufacturers build blinds to suit their own frames. The fabric, the side channels and the brackets are made for a particular unit and locate into positions already formed in the frame, rather than being drilled into a plastered reveal. Fitted that way the blind sits tight to the glass, runs true and reads as part of the window.

Adding one later is possible on plenty of units, but it is the awkward version of the same job, and it gets more awkward the higher the rooflight sits. Somebody has to work overhead at the frame with a drill and a level, on a unit that may be above a stairwell or at the top of a vaulted ceiling. Where the position is out of reach, the sensible moment to deal with it is while access is already in place.

Blinds also come in manual, pole-operated and electric versions, and how far away the unit is usually settles which of those makes sense.

Glazing that leaves the blind less to do

The last point changes how hard everything else has to work. Glass is not a neutral sheet, and a rooflight glazed for its orientation arrives with part of the problem already dealt with.

Solar control glazing carries a coating that admits daylight while reflecting a share of the solar energy back out. It acts at the outer face, before the heat is inside the room, which puts it on the useful side of the line described above. It is not shading and it will not darken a bedroom, but on a south or west slope it lowers the load the room has to handle rather than managing the consequences afterwards.

Size works the same way. More glass than the room needs delivers more heat along with the extra light. We install VELUX, Fakro, Keylite and Roto rooflights, we specify glazing for the orientation rather than from a brochure, and we have been fitting rooflights for fifteen years.