How do I stop glare from a skylight?

There are two separate problems and they wear the same name. The first is direct sun, where the disc of the sun itself, or its reflection, is inside your line of sight through the glass. That is the sharp, painful kind that moves across the room through the day and lands on a screen or a worktop at a particular hour. The second is contrast glare, where the sky beyond the glass is far brighter than the ceiling and walls around the opening, so your eye keeps being pulled towards a glowing rectangle even though no direct sun is involved. A north-facing rooflight under flat cloud can still be uncomfortable for exactly this reason.

The reason it matters is that the two respond to different remedies. Direct sun is beaten by anything that blocks or filters the beam: a coating, a blind, external shading, or moving the glazing itself. Contrast glare is beaten by lifting the brightness of everything around the opening and by softening the light so it is not a single hot source. Spend an afternoon noticing when the discomfort happens and where you are looking when it does, and you will know which lever to pull.

If the skylight is not in yet, the glass itself is the strongest tool you have, because it works on every sunny day without you touching anything. Three properties are worth naming when you order.

• Light transmittance. This is the percentage of visible daylight the unit lets through. Clear double glazing sits somewhere around 70 to 80 per cent. A unit chosen deliberately for a bright aspect might be nearer 50 to 60. Lower transmittance means less dazzle, at the cost of a slightly darker room, so it is a judgement about how much sky you want to look at.
• Solar-control coating. A coating specified to hold down heat gain also knocks back some of the visible brightness, and it is the same coating that keeps a low G-value on a sunny roof. If you are already asking for solar control because the room overheats, you are getting a measure of glare relief for nothing.
• Diffusing or obscure glazing. A satin, acid-etched or opal interlayer scatters the incoming light instead of passing it straight through. It turns a hard beam into a soft wash and removes the bright disc entirely. You lose the view of the sky and clouds, which some people want and some do not, so it suits a bathroom, a stairwell or a deep utility room better than a kitchen you sit and eat in.

Diffusing glass is the one people forget, and it is often the neatest answer to contrast glare because it removes the source of the problem rather than dressing around it. A pitched roof window over a landing, obscured, throws light down the stairs without ever becoming a thing you squint at.

If the unit is fitted and you would rather not replace it, the answer comes from inside. Fitted blinds made for the specific rooflight are the usual route, and they come in a few forms worth knowing apart.

A pleated or cellular blind sits in side channels against the glass and filters the light to a soft, even level while still letting some through, which handles contrast glare well. A blackout blind in the same channels stops the light almost completely, which is what a bedroom or a media room wants for direct sun. A translucent roller does a middle job. Most branded roof windows take a made-to-measure blind that clips into the frame, and if yours is a standard size the choice is wide; our Velux window installation pages cover which units take which blinds. The thing to avoid is a loose fabric shade hung below the opening, which sags, gathers dust and does little for the brightness at the edges.

A retrofit diffuser panel is the other option: a translucent sheet fitted below the glass that spreads the light. It is a reasonable answer in a room where you never want the clear view back and you do want the glare gone for good, though it is a compromise against simply having specified diffusing glass in the first place.

The most effective block of all sits outside the glass, because it stops the light before it enters. An external awning, a slatted brise soleil or a planted pergola over a flat-roof opening will cut direct sun hard while leaving the sky visible, and it does the same for heat, which is why it earns its place on a hot room. It is more of a project than a blind, but on a large lantern it can be the difference between a usable and an unusable room in July.

The room helps too, and this is the half people skip. Contrast glare is a ratio, so raising the brightness of the surfaces around the opening lowers it. A pale, matt ceiling and light walls near the skylight narrow the gap between the glowing glass and everything else, and a splayed reveal, where the plasterboard around the opening is angled outwards rather than cut square, bounces daylight down the slopes and softens the transition. None of this removes the sun, but together it takes the edge off the raw brightness that tires your eyes on a dull bright day.

Around here the glare question and the heat question are the same question. Southend faces south across the Thames Estuary, the southern horizon over the water is open with nothing to shade it, and light bounces up off the estuary on top of the direct sun, so seafront and south-facing rooms can feel glary even when the sun is off the glass. A rear extension on one of the many 1930s semis whose gardens face south collects all of it. If a room like that overheats and dazzles, the two are worth solving together, and the glass specification does both at once. That pairing is the whole basis of our energy-efficient skylight installation work: orientation first, then the glass, then the unit.

If your glare comes from a rooflight that is old, misted or simply the wrong glass for a bright aspect, the moment it comes out is the moment to put that right, because the opening and the upstand are already there and the only variable left is what goes back in. A like-for-like swap to solar-control or diffusing glass changes the room without changing the roof. You can see where the glass options land against a clear unit on our skylight installation costs page.

So: name which glare you have, then match the tool to it. Diffusing or lower-transmittance glass if you are still choosing; a fitted blind or external shade if the unit is in; and pale, splayed surfaces around the opening either way. If you would rather we looked at the aspect and told you which glass to ask for, ring 01702 898232 or request a quote, and we will read the whole roof rather than just the opening in it.