Questions to ask a skylight installer before you book

The first conversation tells you a great deal, because the questions a firm asks you are as revealing as the answers it gives.

A careful installer wants to see the room, the roof and the ceiling below before naming anything. A rooflight is a hole cut through a structure, and the price, the product and the method all depend on what is underneath the tiles or the felt. A quote given from a photograph and a rough size is an estimate of the glass, not of the job.

So ask the first question plainly: will someone visit and survey before I am given a price? If yes, ask what they will look at. A good answer mentions the rafters or joists around the opening, the roof covering, the access inside and out, the pitch or the fall, and what the room is used for. A better answer also mentions listening, which sounds odd until you have lived under a thin pane next to a flight path.

Then ask who does the survey and who does the work. Sometimes they are the same person. If the surveyor hands the job to a subcontractor, you have every right to ask who that is and whether they have fitted this product before. Crews who fit roof windows daily are not the same as crews who fit flat-roof lanterns a few times a year.

A price in an email is not a specification. The paperwork is where a careful firm separates itself, and it costs nothing to ask for it.

Ask for the quote to name the product, the size, the glass build, the colour and the finish. Ask what is included inside the room: making good the plaster, the reveals, the decoration and any blinds. Ask about scaffolding or access equipment, waste removal and protection for floors and furniture. Our page on what a rooflight quote should include gives a fuller checklist to hold a quote up against.

Two more things belong on the page. The first is the glass itself. If the quote says only "double glazed unit", you do not know what you are buying. The second is a description of how the room is expected to sound. We call ours the quiet spec, and it comes with every quote: the noise we heard at the survey, the glazing build we propose and why, and how the seals and upstand are finished. Whichever firm you choose, asking for something in that spirit is sensible.

Much of this is invisible to you until something goes wrong, so it is best to ask about it at the start.

Cutting a new opening in a roof, or changing the structure around it, is building work. Whether it is notifiable depends on what is being done. A like-for-like replacement of a glazed unit is treated differently from a brand new opening, and a change of size changes the answer again. The useful question is who decides whether Building Control needs notifying, and who does it? At Clear Skylights, we handle the notification where the work is notifiable, and we install to current Building Regulations. Our pages on whether a new rooflight needs Building Control sign-off and whether replacing one is notifiable explain the difference.

Ask too about the regulations that touch a rooflight directly. Part L covers thermal performance, and the glazing has to meet it. Part K covers safety glazing in doors and low panes, and good practice makes laminated glass the usual choice overhead. Part F covers ventilation, which matters if the rooflight changes how a room breathes. A good installer mentions these without being prompted. The overview is on our Building Regulations for rooflights page.

Planning is a separate matter. Most single rooflights on a house roof are straightforward, but conservation areas, listed buildings and flats follow different rules. Ask whether planning needs to be checked for my address, and who checks it. See planning permission for rooflights and skylights.

Most buyers ask about price and waterproofing. Fewer ask about what the room will be like to sit in, and it is the question that separates a careful firm from a quick one.

• What is the inner pane made of? Laminated glass is the answer you want overhead.
• Are the two panes the same thickness? Matched panes vibrate together and pass more noise.
• How is the upstand built and insulated? A hollow kerb can boom in rain.
• What will stop heat building up in summer? A solar control coating, a blind or an opening vent are the usual answers.

If the installer has no view on any of these, the glass is being chosen from a catalogue, not for your room. You may also want to read whether acoustic glass is worth it before you talk to anyone, so you know which way you are leaning.

Good work rarely needs the guarantee. You still want to know what it says before you sign.

Ask what is guaranteed, for how long, and in what form. Ours is a 10-year workmanship guarantee, and we are plain that it is a workmanship guarantee and not an insurance-backed one. Read the terms on our guarantee page. Whatever a firm offers, ask who stands behind it if the firm changes hands, and whether the glass has its own manufacturer warranty separate from the fitting.

Ask what happens to my room during the job. A rooflight means a hole in the roof for a short time. A careful installer talks about weather, about when the opening is exposed, about covering it overnight and about how long the room is out of use. Our note on installing a skylight in the rain shows what that conversation should sound like.

How long will it take, and what will be in the way?

A straight swap of a roof window is often a matter of hours, while a new opening with structural work takes longer. Ask for both the duration and the disruption. How long it takes to fit a new rooflight has the detail.

Can I see a finished example of the product I am buying?

A photograph of a similar job is useful. A careful firm can show the type of unit, the upstand and the inside finish, not only the glass seen from the garden.

Do you work in my area?

We cover Crawley and 30 miles around, from Horsham and Haywards Heath to Reigate, East Grinstead and Brighton. Ask any firm how far it travels and who turns up if the job overruns.

What do you need from me before you start?

Access to the loft or the room, a clear floor and a decision on the glass build. Ask for a date by which each choice has to be made, because made-to-order units cannot be changed once ordered.

If you would like to put these questions to us, get a quote or read more about skylight and rooflight installation in Crawley.