Do roof windows need blinds?

A roof window sits high in the ceiling with an open view of the sky, which is exactly what you want for daylight and exactly what works against you at four in the morning in June. There is no house opposite and no street light to filter, so the glass fills with light the moment the sky does. Over a bed that matters more than over any other spot in the house.

Bedrooms are the clear case. A blackout blind that runs in side channels, so no light leaks down the edges of the glass, is close to essential over a loft bedroom or a child’s room. Without one the room brightens with the sunrise regardless of the clock, and in a converted loft the bed is usually right under the glass because that is where the headroom is.

Studies and home offices are the next tier down. There the problem is not sleep, it is a bright patch landing on a screen for part of the day. A blind you can pull across the worst of it, rather than a full blackout, is usually enough. Bathrooms, landings, halls and utility rooms come bottom of the list. They are used briefly, glare rarely bothers anyone in them, and a north-facing one that never catches direct sun can reasonably go without.

This is the part that trips people up, so it is worth being precise. An internal blind is very good at glare and only modest at heat. Glare is the visible brightness that makes you squint or washes out a television. Pull a blind across and it is gone, because you have put something opaque between your eye and the bright sky. That part works instantly and it is why blinds sell.

Heat is a different matter. By the time sunlight has passed through the glass and hit the back of an internal blind, most of its energy is already inside the room. The blind warms up and radiates that heat straight back out into the space. So an internal blind takes the edge off glare beautifully and does far less for a room that is actually overheating. If you have ever sat under a closed blind on a hot afternoon and still felt the warmth coming off it, that is the physics in action.

The tool that genuinely stops heat is external shading, an awning blind fitted on the outside of the glass, because it blocks the sun before it ever reaches the pane. External blinds are more expensive and need power or a manual crank to reach them, but for a west or south-facing room that bakes in the afternoon they do the job an internal blind cannot.

Roof windows are not vertical, so a standard hanging curtain or a loose roller is no good: the fabric would sag away from the glass. Blinds made for roof windows run in side channels or on tensioned wires so they stay flat against the pane at any angle. Here is what is usually on offer.

Most manufacturers cut their blinds to the exact window size and colour-match the side channels to the frame, so a fitted blind looks like part of the unit rather than an afterthought. If you know a room will want a blackout blind, it is worth choosing the window and the blind together, because a matched blind clips into grooves already machined into the frame.

A blind adds a modest amount to a window over the bare unit, more for a powered or external one. The practical question on a pitched roof is reach. If the window is high on a loft slope you cannot lean out and grab a cord, so a blind wants either a long telescopic rod or a motor. Motorised blinds pair naturally with a motorised window, and if you are already running power to an opening rooflight it is little extra to wire the blind onto the same circuit. That is worth planning at installation, because chasing a cable up to the ridge later is disruptive. If you want the window itself to open and close on a switch or a sensor as well, our electric skylight installation and VELUX window installation pages cover how that is set up.

This is where the estuary comes in. Southend faces south across the Thames, so a great many rear extensions and lofts across the city catch sun on the glass from mid-morning to late afternoon through the whole warm half of the year. If your roof window faces that way, a blind is treating the symptom. The room will still gain heat every time you open the blind for the view, and it will still run warm.

The setting that actually governs summer heat is the G-value of the glass, the share of the sun’s energy the pane lets through. Clear double glazing sits around 0.6; solar-control glass drops to about 0.3, which roughly halves the heat coming in before you have hung anything at all. For a south-facing pitched window the sensible order is solar-control glass first, then a blind for glare and privacy on top. Get the glass right and the blind stops carrying a load it was never built for. Our energy-efficient skylight installation work is built on exactly that reasoning, and it is why we specify the glass before we ever talk about accessories.

Work through it room by room. Decide what each roof window is for, note which way its roof faces, and match that to the table above: blackout over beds, filtering blinds where glare is the issue, external shading or better glass where the room overheats, and nothing at all where a north-facing window has never caused a problem.

If the window is south-facing, deal with the glass specification before you spend on shading, because the blind is doing glare and the glass is doing heat, and they are not interchangeable. Choosing the window, the glass and the blind together is far tidier than adding pieces afterwards, and it is the whole idea behind a proper pitched roof skylight installation. Tell us the orientation, the room and the rough size, ring 01702 898232 or request a quote, and we will specify the glass and the blind as one job rather than two.