Skylight blinds

The problem is gravity, not the fabric

Every ordinary blind in a house works because it hangs. Fabric under its own weight falls straight down, and a vertical window is straight down, so the two agree and the blind lies flat against the glass.

Turn the window through forty-five degrees and they stop agreeing. The fabric still falls plumb; the glass now leans away from it. The blind ends up suspended in the room with a widening wedge of air between it and the pane, and at the bottom of the window that wedge can be a hand’s width.

That is the entire reason a skylight blind is a different product. It has side channels — slim tracks down both sides of the window — and the edges of the fabric run inside them, so the blind is physically held to the slope rather than left to hang. The mechanism above and below is otherwise ordinary.

Two things follow from this that people should know before buying.

Anybody selling a plain roller for a sloped window is selling something that will not work. It is not a matter of quality or price. It is geometry.

The channels are not an upgrade, they are the product. The cost of a skylight blind is largely in the tracking and the fitting, which is why it is not priced like a roller of the same size.

Heat is usually the real reason

People ring about skylights in July, and almost never about privacy.

Roof glass takes the sun differently from a wall window. Through the middle of the day the sun is high, so it strikes a horizontal or shallow-pitched pane close to straight on while a south-facing wall window is receiving it at a glancing angle. The same area of glass therefore admits substantially more solar energy through the roof than through the wall.

The practical result is familiar: a loft, a converted attic or a kitchen extension with roof lights becomes the hottest room in the house, and stays hot into the evening because the heat has gone into the fabric of the room.

What a blind can do about it is real but bounded. A blind sits on the inside, so the energy has already come through the glass before the fabric sees it. It stops that energy becoming light and glare in the room, and a reflective-backed fabric returns some of it back out through the pane — but a portion has already been absorbed by the glass itself.

So the honest ranking, and we will say this at the visit rather than after:

External shading beats any internal blind for heat, because it stops the energy before it arrives. If the roof light is accessible and heat is the whole problem, an external awning or solar-screen is the better engineering answer and we will say so.

A reflective internal blind is the best interior option and makes a substantial difference to comfort.

A dark decorative fabric looks lovely and does the least for heat, for the same reason a dark screen does on a wall window: it absorbs and re-radiates inward.

Getting a room genuinely dark

The other half of the work, and the one where roof blinds outperform.

A loft bedroom with an uncovered roof light is the brightest bedroom in a house at 5am in June, because the sky is directly overhead and there is nothing between the two. Curtains cannot be hung on a slope. This is the single most common reason for a blackout skylight blind and it is the case where the product is transformative rather than incremental.

It works better than a blackout on a wall window because the same channels that solve the gravity problem also enclose the fabric’s edges. On a vertical window, side channels are an optional extra that many people skip; on a skylight they are inherent, so the light path down each side is closed by design.

What remains is the head and the foot. A well-fitted blind closes both with a cassette at the top and a bar seating into the bottom channel, and the difference between a good fit and an adequate one on a roof light is almost entirely there.

Which fabric, for which problem

Blackout with a reflective backing. The default for a bedroom. Dark on the room side, silver or white on the glass side so it reflects rather than absorbs. Does both jobs — the room goes dark and the heat gain drops.

Solar screen. For a kitchen, a stairwell or a landing where you want the light and not the glare. Keeps the sky visible, cuts the harshness.

Cellular. The one we suggest where winter matters as much as summer. The cells trap air against the glass and roof glass is where a house loses heat fastest at night, because warm air rises straight to it. In a converted loft used year round this is often the right answer even though it is the dearest.

Anything decorative. Fine on a landing. Not on the roof light in the room somebody sleeps in.

Reaching it

The unglamorous constraint that decides whether the blind gets used.

Within reach or close to it. A telescopic pole with a hook. It works, it costs almost nothing, and it lives in a cupboard. Be honest with yourself about whether it will be fetched twice a day.

Above about three metres, or in a room used daily. A motor. On a roof light this is a stronger argument than on a tall wall window, because a roof blind needs adjusting with the sun rather than once a day, and nobody adjusts anything with a pole four times.

Where the roof window has its own control rod — some manufacturers’ units do — we work with what is there rather than adding a second system.

Power is the practical question above a stairwell: a battery motor has to be recharged, and if getting a cable to the blind is itself a ladder job then hardwiring during any other work is far cheaper than doing it later.

What we need to know before quoting

More than for any other product, because roof windows are made to models rather than to sizes.

The brand and model code. Usually on a plate inside the frame, visible when the window is open, sometimes on the glass edge. A tracked blind made for that unit fits precisely and clips to the frame without fixings into plaster.

The pitch. How steeply the window leans. It changes the channel specification and, on a shallow pitch, whether the bottom bar needs weighting to keep the fabric taut.

The reveal. Roof windows usually sit in a plastered shaft that flares — vertical at the top, angled at the bottom, or splayed on all four sides. The blind fits the window, not the shaft, and knowing the shaft’s shape decides whether it will be visible around the blind.

The reach. Measured to the bottom of the window from the floor, standing where a person would stand.

None of that can be supplied over the phone reliably, which is why this is a product we quote after a visit rather than before.

Where we would tell you not to bother

A roof light over a bathroom. Steam rises, and a blind against roof glass sits in the wettest air in the house. If the room is properly ventilated it is fine; if it is not, the blind will show it.

A small roof light in a hallway. If nobody is under it and nothing is fading, it is doing its job by being uncovered.

A north-facing roof light in a cool room. It is not a heat problem, it is not a glare problem, and covering it removes the daylight it was cut into the roof to provide.

Last updated 9 August 2026.