Choosing a Rooflight Installer

Chapter 1

Start with the survey, because the quote can only be as good as the visit

A rooflight quote written from a phone photo is a guess about your roof and a bigger guess about your room. Before choosing a rooflight installer, look at how each one surveys, because everything that follows depends on what they measured and what they noticed.

A proper survey happens in two places. Outside, someone should look at the roof covering (slate, plain clay tile, concrete interlocking tile, felt, single-ply membrane or lead), its pitch, its condition and how the opening will be reached. Inside, they should measure the ceiling, the rafter or joist spacing, the depth of the roof build-up and the height of the room. On a pitched roof the gap between rafters decides which widths fit without trimming. On a flat roof, the depth of the deck and the existing falls decide how the kerb or upstand is built and where the water goes.

The better visits also cover the questions that sit around the unit itself. Is there a party wall close to where the skylight is wanted? Is the house in a conservation area, or is it a flat, where permitted development does not apply? Is there wiring or a soil pipe in the void? Will a scaffold tower do, or does the street need a licensed scaffold? In a Romsey or Mill Road terrace with no side access, that last question can shape the whole job, and it is far better raised at the survey than on the morning of the fit.

Notice, too, whether the surveyor asks how you use the room. Where does the desk go? Which end of the kitchen do you cook at? Do you sleep in the loft room in summer? Those answers change the right position and glass more than any tape measure does. If a visit ends without anyone asking what the room is for, the quote that follows is about a hole in the roof, not about the light you are paying for.

Chapter 2

What the written specification should name

Two quotes for "one skylight, supplied and fitted" can describe completely different products and completely different jobs. The only way to compare them is a written specification that names the details.

Ask each installer to put the following in writing, not just in conversation on the doorstep:

• The make, model and exact size of the rooflight, and whether it opens (manually or electrically) or is fixed.
• The glazing: double or triple, the U-value, the g-value (how much solar heat gets through), whether the inner pane is laminated, and any solar control or self-cleaning coating.
• For a flat roof, the upstand or kerb: its height above the finished roof, what it is built from and how it is insulated.
• For a pitched roof, the flashing kit that suits your tile or slate profile, and the install depth.
• The internal lining: plasterboard reveals, whether they are splayed to spread the light, insulation around the frame and the finish they will be left in.
• Blinds, if you want them, and whether they sit inside or outside the glass.
• Access equipment, waste removal, and what is and is not included in making good.

A quote that gives a product name but leaves the glass, the upstand and the lining blank leaves you comparing prices for things that might not be the same. It is not a sign of bad faith: it is just incomplete, and you are entitled to ask for the gaps to be filled before you sign anything. If the words in the quotes do not match (one says rooflight, another roof window, a third lantern), our guide to the difference between a rooflight, a skylight and a roof window will help you check you are comparing like with like, and the types of rooflight sets out what each one is best at.

Chapter 3

Ask about the light, not only the unit

The thing you will live with every day is not the frame or the flashing. It is where the daylight lands, how hot the room gets on a July afternoon, and whether the sun glares across a screen at four o'clock.

Cambridge is flat, with a big open sky and very little to shade a roof, so the direction a slope faces decides a great deal. A north slope gives steady, soft light all day with little heat. A south slope gives hours of direct sun that you will want to control with glass and blinds. East and west slopes bring low, raking sun early or late, which is lovely in a breakfast room and difficult over a television. Our guide to which way a skylight should face covers this in detail.

Good questions to put to any installer:

1. Which way does this slope face, and what will that mean for the room in winter and in summer?
2. Where will the patch of sunlight fall at different times of day, and is that where we want it?
3. Which glass would you choose for this orientation, and why that g-value?
4. Would a smaller unit in a better position light the room more evenly than a bigger one where we first pointed?
5. Will we need a blind, and if so which kind?

A clear, reasoned answer to each is a good sign. We think this matters enough that every Vision quote comes with a written light plan: the position, size, glass and shading we recommend, and the reason for each choice. You can read how that works on how we plan the light. Whoever you choose, ask them to write their reasoning down, because a recommendation on paper can be checked, questioned and compared.

Chapter 4

Planning and Building Control: who does what

These are two separate systems, and a good installer will be clear about which one applies to your job and who is taking care of it. Planning is about how the house looks and affects neighbours; Building Control is about whether the work is safe, warm and sound.

On many houses, a new rooflight is permitted development, provided it does not project more than 150mm from the roof plane, does not rise above the highest part of the roof, and meets the rules on side-facing glazing. Flats and maisonettes do not have those rights, listed buildings need consent, and conservation areas or Article 4 directions can bring extra limits. Across Greater Cambridge, East Cambridgeshire and Huntingdonshire the local position varies, so ask the installer whether they have checked it for your address. Our guide to planning permission for rooflights in Cambridge explains where the lines usually fall.

Building Regulations apply whether or not planning permission is needed. A new rooflight cut into a roof, or an enlarged opening, is normally notifiable work: the thermal performance of the glass, the strength of the structure around the opening, safety glazing overhead, fire performance near a boundary and ventilation all come into it. Ask plainly: "Who is notifying Building Control about this work, and what document will I receive at the end?" A completion certificate matters when you come to sell, and a missing one can mean a delay or an indemnity policy later. Our guide to Building Regulations for rooflights covers which parts apply.

At Vision we handle the Building Control notification where the work is notifiable and install to current Building Regulations, so the paperwork arrives with the finished job rather than as a separate task for you.

If your house is terraced or semi-detached and the rooflight sits close to the shared wall, ask whether the Party Wall etc. Act 1996 is relevant. It often is not for a straightforward rooflight, but an installer who raises the question unprompted is one who has thought about your particular house.

Chapter 5

The day itself, access and making good

Most of the disruption from a rooflight job happens inside the room, not on the roof. Asking how the day runs, and what the room will look like when the team leaves, tells you a lot about how an installer works.

For a single pitched roof window swapped like for like, the work can be done in a day. A new opening with trimmed rafters, a fresh lining and plastering takes longer, and a lantern on a new upstand longer again, with the plaster needing time to dry before decoration. Ask for a realistic programme in writing, including any second visit for plaster or finishing. Our answers on how long skylight installation takes give typical timescales by type.

Then ask about the practical things:

Protection. Opening a ceiling brings down dust and old plaster. Floors, stairs and furniture should be sheeted, and the room below cleared or covered.

Weather. What happens if rain arrives with the roof open? A careful team watches the forecast and has temporary covers ready, and will reschedule rather than gamble.

Making good. This phrase covers everything from rough plaster ready for your decorator to a finished, painted reveal. Neither is wrong, but you need to know which you are buying. Ask whether the reveals will be plastered, skimmed and painted, whether insulation is fitted around the frame to prevent cold spots, and who touches up the ceiling around the new lining.

Waste. Old units, tiles, battens and plaster need taking away. Check it is included.

If you are replacing a tired or misted rooflight rather than adding a new one, the same questions apply, plus one more: can the new unit go into the same opening, or will it be upsized or moved? Our pages on skylight replacement options and the rooflight replacement process go through those choices step by step.

Chapter 6

Guarantees and warranties are two different promises

When you are choosing a skylight installer, the word "guarantee" can mean several things. Separate the promise about the product from the promise about the fitting, and get both in writing.

The manufacturer's warranty covers the rooflight itself: the glazed unit, the frame, the opening mechanism, the motor if it is electric. Its length and terms depend on the maker and the product, and some parts (motors, sensors, blinds) often carry a shorter period than the glass. The installer's workmanship guarantee covers the installation: the flashing, the upstand, the weathering, the lining and the way the unit was fixed into your roof.

Questions worth asking each firm:

• How long is your workmanship guarantee, and what exactly does it cover?
• What does it exclude? Damage, later alterations by others and the manufacturer's own product warranty are the usual exclusions.
• How do I raise a claim, and who do I contact?
• Will I receive the product warranty details and registration in my name?

Vision gives a 10-year workmanship guarantee on the installation work, set out in writing with the quote. You can read what it covers, what it does not and how to claim on our guarantee page. Whatever firm you choose, keep the guarantee, the product warranty, the Building Control certificate and the invoice together, because a buyer's solicitor may ask for all four one day.

Chapter 7

Comparing quotes side by side

Once two or three written quotes are in, lay them next to each other line by line. The one that reads most completely is usually the one that has thought hardest about your house.

A simple grid makes the gaps obvious. Fill in one column per quote and look for blanks:

The final figure matters, of course, and our page on skylight and rooflight costs explains what drives it: the roof type, access, the size and glass of the unit, structural work and the level of finish. But a lower total that leaves out the lining, the scaffold or the Building Control fee is not really lower; it just moves those costs to later. Ask each installer to confirm in writing what is included and what is not, and compare the totals only once the scope matches.

Two more things are fair to weigh. First, how clearly the firm explained things: whether you came away understanding why they proposed what they did. Second, how they handled your questions. A rooflight is in your roof for decades, and an installer who answers a question patiently before you sign is likely to do the same afterwards.

Chapter 8

Questions people ask

Should a general builder fit my rooflight or a rooflight specialist?

Either can do good work. What matters is the checklist above: a proper survey, a written specification, a clear answer on Building Control, a defined level of making good and a written guarantee. If a builder is already doing your extension, ask them the same questions about the rooflight as you would ask anyone else, and ask who is choosing the position and the glass. Our guide on skylight ideas for extensions may help you frame that conversation.

Is it reasonable to ask for a light plan with the quote?

Yes. It is your room and your money, and a short written note on where the unit goes, how big it is, which glass it has and why is not a big ask for an installer who has visited. Every Vision quote includes one as standard.

How many quotes should I get?

Two or three is usually enough to see the range of approaches. More than that tends to blur the comparison, especially if the specifications differ.

What should I have in hand when the job is finished?

The invoice, the workmanship guarantee, the manufacturer's warranty details, the Building Control completion certificate where the work was notifiable, and any operating notes for an electric or opening unit. If you would like us to look at your roof and room, book a light survey or message us on WhatsApp, and you can read more about us on the skylight and rooflight installation homepage.