The short answer: Yes. You can add a skylight to an existing roof, whether it is pitched or flat. A new opening is building work, so the rafters or joists are trimmed around it and the opening is weathered and checked by Building Control. Houses often need no planning application, but flats always do, and some streets have had that right removed, so check with the council before you order anything.
Cutting a hole in a roof that has kept the weather out for decades feels like a big step, and it is a fair thing to worry about. It is routine work when the structure is looked at first. This page walks through what has to be true of your roof, what the rules say, and how the job runs. For the wider picture of what we fit across the city, start at the Brighton and Hove skylight and rooflight home page.
What the roof has to allow
The first question is not the glass. It is what sits under the tiles or the membrane. Every opening interrupts something that carries load, so someone has to look at it before a price makes sense.
In a pitched roof the opening usually cuts through one or more rafters. Those rafters are not simply removed. Short timbers called trimmers are fixed across the gap, and the cut rafters are fixed to them, so the load travels round the opening instead of through it. In a flat roof the same idea applies to joists, with a kerb built up around the opening so water has somewhere to shed.
Some roofs make this harder than others. Older cut timber roofs may have been altered before, with purlins and struts in the way. Trussed roofs, common on later houses, are designed as a whole, and cutting a truss member without an engineer's advice is not something to improvise. A butterfly roof, with its two slopes falling to a central valley gutter, puts the valley right where you might want light. A mansard has a steep lower slope and a shallow upper one, and each takes a different type of unit.
This is why we start with a free survey. We look at the roof from inside the loft where we can, and from the outside where access allows, then write up what the structure will take.
Pitched roof or flat roof
The two roof types lead to two different products, and they are covered by different energy standards.
| Roof | Usual unit | What is built around it |
|---|---|---|
| Pitched, tiled or slated | Roof window | Trimmers between rafters, a flashing kit, battens cut to suit |
| Flat, felt or single ply | Flat roof rooflight | A timber or insulated kerb, an upstand, new roof covering dressed up to it |
| Flat, with room for a feature | Roof lantern | A kerb sized to the lantern base, often with a structural trimmer |
| Tight or tall spaces | Sun tunnel | A small round opening and a flexible or rigid tube |
On a pitched roof, a roof window is the normal choice, and the VELUX range covers most standard rafter spacings. On a flat roof you are choosing between a flat roof rooflight and a roof lantern. Where the ceiling void is awkward, or you only need daylight in a landing or bathroom, a sun tunnel avoids cutting a large opening at all.
Do you need planning permission
For a house, often not. Rooflights are covered by permitted development under Class C, provided they stay within the conditions. Three limits apply: the unit may stand no more than 150 mm proud of the roof plane, its top must stay under the roof's highest point, and a unit in a side-facing slope needs obscured glass and no opening sash within 1.7 m of the floor.
There are three common reasons that right does not apply to you.
- You live in a flat. Permitted development does not cover flats, so adding a rooflight means applying for planning permission.
- The council has withdrawn the right. That happens through an Article 4 direction, or through a condition on an earlier planning permission; living in a conservation area does not do so by itself. Many of the conservation areas in Brighton and Hove are covered by council Article 4 directions, so put your address to the council before you commit.
- The building is listed. Listed building consent is needed on top of planning, for any change that affects the character of the building.
A house within the boundary of the South Downs National Park answers to the Park Authority for planning, not to the district council. The full picture, with the conditions in order, is in our planning guide for rooflights.
What Building Control looks at
Cutting a fresh opening into a roof counts as building work, with or without a planning requirement. Building Control covers four things: the structure around the opening, the weathering at its edges, fire safety, and energy performance.
On energy, the figures are published. For a pitched roof, the new roof window has to achieve either 1.4 W/m²K or Window Energy Rating band B. On a flat roof, a rooflight or lantern is held to 2.2 W/m²K. Those are the standards for existing dwellings, and the units we supply are chosen to meet them. The detail is in the Building Regulations guide for skylights and rooflights.
Where a new opening is notifiable, we do the Building Control paperwork ourselves, filing with the council or with a registered building control approver. You do not have to chase that yourself.
One thing to know if the new opening is in a loft being turned into a bedroom. A roof window works as an escape route only when the storey is no more than about 4.5 m off the ground, which suits a bungalow or chalet bungalow. On a two storey house, a loft room needs a protected stair, and a roof window does not replace it.
Reaching the roof for the new opening
In Brighton and Hove the roof is often the hardest part of the job to reach. Tall terraces, parapets, steep streets and permit-only parking all affect how materials go up and how old units come down.
Every quote we write includes a one page access plan. Its first job is to choose the way up to your roof: scaffolding carried through the garden, a tower built from the pavement, or a mobile platform. It also names who applies for the scaffold licence and any bay suspension from the council, and that is us. For converted buildings it covers the freeholder's consent and the notice given to neighbours. It also names the Building Control route and the price. You can read how this works in the access plan, and the licensing side in our note on scaffold licences and parking suspensions.
Scaffold or street licences come from the highway authority, which for most of the city is Brighton and Hove City Council. Outside the city, the licence usually comes from East Sussex or West Sussex County Council instead.
How the job runs
- Free survey. We check the roof, the loft or ceiling below, and the access, and talk through where the unit should go.
- Fixed written quote. It includes the access plan, so the price covers getting to the roof as well as fitting the unit.
- Consents. Planning, if your property needs it, is for you to apply for, with our drawings if useful. We deal with the scaffold licence and the Building Control notification.
- Opening and framing. We strip the covering, trim the structure, and fix the kerb or flashing kit.
- Weathering and finishing. The unit is fitted and sealed into the roof covering, and we make good inside around the new opening.
Our guarantee page sets out the 10 year workmanship guarantee that covers the finished work. For the length of time the work takes on site, see how long it takes to fit a skylight.
Where to go from here
If you already have a position in mind, measure it from inside and note what is above and below it. A photograph of the ceiling and the roof from outside, if you can take one safely from the ground, helps us at the survey. If you are unsure whether you want a skylight or a rooflight, our page on skylight or rooflight explains the words, and the price drivers are on the costs page.
To go ahead, request the free survey on the quote form, or ring 01273 282313.Back on the main page you can see every type of unit we fit.
