Rooflight Questions Answered

This is the short-form half of the site. Each page below takes one question, answers it in the opening line, and then spends the rest of the page explaining the answer well enough that you can act on it. No preamble, no scene setting, no working up to the point. If the question you have is a single question, this is the faster place to look.

One question, one page, and the answer in the first line

The format is deliberate and it is the same on every page. The question is the title. The first sentence of the body is the answer, stated plainly, including when the plain answer is that it depends on the pitch or the covering. Everything after that exists so you can tell whether the answer applies to your roof, what would change it, and what to do next.

That means these pages are designed to be abandoned early. Reading two lines and leaving is a successful visit. A great many questions in this trade have a short true answer that the industry tends to wrap in qualifications, and stripping those away is most of the value here.

How these differ from the guides

Both bodies of writing are technical and both are written by the same hands. The difference is scope, not seriousness.

A guide takes a subject: how a rooflight is sized to the structure it sits in, or how glazing specification follows orientation. It works through the subject from several directions, carries tables, and expects a reader with time. An answer takes a question: whether a rooflight can go into a trussed roof, or whether a particular unit counts as an escape window. It gives the reply and enough surrounding detail to use it.

In practice people move between them in both directions. A question answered here often raises a second-order question that only a guide has room for, so the answers link across to the relevant guide where one exists. Equally, a guide will link down to an answer rather than absorbing a narrow question into a long section where nobody would find it. Where the question is about a specific piece of work, both link to the service page that describes it.

Where the questions came from

These are not invented to fill a page. They are the questions asked on scaffolds, at kitchen tables, in the first email and halfway through a survey, collected across fifteen years of putting glass into roofs.

That origin shows in what they cover. A fair number are about permission, because the rules are genuinely confusing and the consequences of getting them wrong are expensive. A fair number are about condensation, because water appearing on the inside of glass looks exactly like water coming in and is usually neither. Some are about noise, heat and blinds, which nobody thinks to ask until they have lived under a rooflight for one summer. Some are about the practical shape of the work: how long it takes, whether you need to move out, what happens to the room below, what happens if the weather turns.

Several are the questions people are slightly reluctant to ask out loud, about whether a quotation is reasonable or whether a previous installation was done properly. Those get straight replies too.

Filed under the same four headings as the guides

The questions sit in the same four groups the longer writing uses, so moving between the two does not mean learning a second filing system.

• Choosing holds the questions asked before anything is ordered: what fits, what is allowed, what suits the roof, what size is realistic.
• Specification holds the questions about the unit and the detail: glass, coatings, opening mechanisms, flashings, upstands, insulation.
• Living with it holds everything that comes up after the scaffold has gone: condensation, heat, noise, cleaning, ventilation, blinds and how a unit ages.
• Costs holds the questions about what moves a price and how to read what you have been sent, alongside the costs page.

Within each group the pages sit in no particular order of importance, because a question is either yours or it is not.

Reading an answer that nearly matches your roof

Most answers here are conditional on something, and the condition is stated. Three of them do most of the work, and it is worth checking them against your own roof before treating an answer as settled.

Pitch. A great many answers change at around fifteen degrees, which is roughly where a manufactured in-plane roof window stops being suitable and a kerb-mounted unit takes over. Others change again at the shallow end, where falls and ponding become the governing issue.

Covering. The method for forming an opening in concrete interlocking tile and the method for Cotswold stone slate are barely the same job. Where an answer says something is straightforward, it usually means straightforward on a modern covering, and it will say so where the stone changes the reply.

Structure. Cut roof or trussed roof is the other great divider. An answer about widening an opening means one thing where rafters can be trimmed to a design and quite another where a triangulated frame has to be carried on a designed member.

If two of those three match your roof and one does not, the answer is probably still useful and the exception is probably the interesting part of your job.

Sending a question of your own

Questions arrive here from real enquiries, so a new one is genuinely welcome and frequently ends up on the site. Email info@severnskylightsgloucester.co.uk. A photograph of the roof from outside and one of the room from inside will usually get a more precise reply than the question alone, because a great deal that is hard to describe in words is obvious in a picture: the covering, the pitch, the abutments, the run of slope and often the age of the construction.

If the question turns out to be about your specific roof rather than about rooflights in general, the reply will say so and point at what would settle it. That is usually a survey, and the reasoning behind that sequence, along with why an indicative range comes first and a fixed price second, is set out on the costs page.