The short answer
A rooflight does not need solar control glass as a rule, but it is worth choosing where the glass faces south or west, the room is a loft bedroom or an extension that overheats, or the glazed area is large. The coating cuts the sun's heat that passes through, at the cost of a little daylight and a little more on the quote.
What solar control glass does
Sunlight carries heat as well as light. Ordinary clear glass lets most of both through, which is a gift in winter and a nuisance on a bright July afternoon. Solar control glass carries a thin coating that reflects or absorbs part of the sun's energy before it reaches the room, while still letting daylight in.
The coating sits on a face of the sealed unit and is invisible from inside apart from a faint tint, often a slight blue, green or grey, depending on the glass. Because it works on the sun's energy, it behaves differently from insulating glass, which holds heat in. A unit can carry both.
Solar control is one option among several, and for many roofs it is not the first one to reach for. It earns its place where the sun is the problem.
Which roofs and rooms gain most
Direction matters most. A rooflight facing south or west takes the strong sun of the afternoon, when the house has already warmed through the day. A north-facing one takes little direct sun and rarely needs the coating.
Room use comes next. A loft bedroom sits directly under the roof and is often the warmest room in the house on a hot night. A kitchen extension with a large glazed lantern or flat rooflight can warm quickly, and it has appliances adding heat too. A hallway or a bathroom with a small roof window usually gets by without it.
Size and shading finish the picture. A big glazed area collects more sun than a small one, and a rooflight shaded by a tree or a neighbouring gable collects less. At the survey we note the direction the roof faces, what shades it, and how the room is used, and say whether the coating is likely to be noticed.
Solar control against other ways to stay cool
The coating is not the only way to deal with summer sun, and the others have their own strengths. Our options for each roof are priced together so you can weigh them.
| Item | Solar control coating | External blind | Internal blind |
|---|---|---|---|
| How it works | Reflects or absorbs part of the sun's energy in the glass | Blocks the sun outside, before it arrives at the glass | Shades the room, but the glass has already warmed |
| Effect on heat | Steady, works all the time | Strongest, used when needed | Weakest of the three |
| Effect on daylight | A little less, always | None when open | None when open |
| Cost | Middle | Higher | Lower |
| Attention needed | None once fitted | Opened and closed, or automated | Opened and closed |
An external blind is usually the most effective, since it stops the sun outside, but it costs more and needs operating. A coating works without anyone remembering. Some homeowners on a hot roof pair the coating with an internal blind. Our answer on blinds at fitting explains how a blind is specified with the window.
What it costs in light and in the quote
Solar control glass lets in slightly less daylight than clear glass, and you may notice a faint tint when you look up through it. For a room with plenty of other light, that hardly registers. For a dark hallway where the rooflight is the only source, you may prefer clear glass.
In the quote the coating shows as an added cost on the glass line. It does not change how the unit is fitted, and depending on the maker it can be combined with double or triple glazing, a self-cleaning coating or a laminated pane.
Winter is the other side. The same coating that keeps summer sun out also stops a little of the free warmth of winter sun, so on a roof that gets strong low sun in cold months the saving can feel smaller than on paper. Our answer on how much heat skylights lose looks at the insulating side of the glass.
Choosing at the survey
We ask which room the rooflight serves, which way it faces, when the room is used and whether it has overheated before. Wherever the roof permits, the written quote lists several suitable units by different makers, some with a coating and some without one, so you can see what each of them adds.
- Roof direction and shading noted
- Clear and coated glass priced side by side
- Blind options listed with the glass
Book a free survey and we will set the options out for your roof. If you are choosing between double and triple glazing as well, our comparison of double and triple glazed rooflights covers that choice.
Related questions
Is solar control glass the same as tinted glass?
The aim is similar, but a modern coating is much clearer than the old heavy tint. You may notice a faint colour looking up through it, and daylight is reduced only a little.
Will solar control glass make my room dark?
The room will be slightly less bright than with clear glass, though in most rooms the difference is small. A dim room that depends on one rooflight is where clear glass may be the better choice.
Can I add solar control to a rooflight I already have?
The coating is part of the sealed glass unit, so it is added by replacing the unit. A window film is a different product, and we check the unit at the survey before advising on either.
Does a north-facing rooflight need it?
Seldom, since little direct sun reaches it. A room that overheats for another reason, such as a loft bedroom with poor ventilation, may do better with an opening rooflight than with a coating.