Do you need permission for a sun tunnel?

A house in England has permitted development rights for roof alterations under Class C of the General Permitted Development Order, and a sun tunnel dome falls within them when it meets the limits. Those limits concern how far the dome stands out from the roof slope, how high it rises against the highest part of the roof, and what faces a side slope. The full conditions are listed under planning and Building Regulations for skylights.

A sun tunnel suits the first limit well, because the dome is a low shape that rises only a short way above the covering. The exact projection differs from one maker's unit to the next, so we read it from the maker's drawing and compare it with the limit before anything is ordered. The tube in the loft and the diffuser in the ceiling are inside the building, and planning rules for roof alterations do not reach them.

The position of the dome on the roof matters as well as its height. A dome set towards the ridge sits closer to the highest part of the roof than one set low on the slope, and we weigh that when we choose where it goes. On a roof where the tube has a choice of route, the dome can often move along the slope without changing the light in the room much, so the planning point and the lighting point are usually settled together.

Permitted development covers the planning side only. Whether it applies still depends on the building, so the next section matters.

Three kinds of building sit outside the simple rule, and each has its own next step.

• Flats and maisonettes. Class C leaves them out, so a dome on a flat or maisonette roof normally means an application to the council. Check with the council before you plan the work.
• Conservation areas. The council can remove permitted development rights in part of a conservation area by an Article 4 direction. Where one applies to your street, a dome on the slope that faces the road may need an application. What the council looks at is described in rooflights in conservation areas.
• Listed buildings. Permitted development does not stand in for consent here: a new rooflight on a listed building needs the council's listed building consent first. The application is described in the application for a rooflight on a listed building.

Some Leeds terraces and villas stand inside conservation areas, so the status of the street is worth finding out early. Planning for a Leeds address is dealt with by Leeds City Council, while a town further out has its own council and planning service.

A sun tunnel is a smaller mark on a roof than a roof window, but it does not change who gives the answer. The council applies the same tests to a dome as to any other rooflight, so the status of the building settles the question, whatever the size of the dome.

Planning and Building Regulations are separate checks, answered by separate bodies, and a sun tunnel can pass the first and still need the second. A new opening in a roof alters its structure, so Approved Document A applies and the job falls under notifiable building work. We notify Building Control, whether that body is the council or a registered building control approver.

A sun tunnel is small enough to pass between two rafters where the spacing allows, which leaves the rafters whole. If a timber in the roof is cut, the work is structural and goes through the same notification. In both cases the paperwork forms part of the installation, and the figure includes it, as the cost of installing a sun tunnel shows.

A short set of questions about the building settles the question at the outset. Ask whether the building is a house or a flat, whether it is listed, whether the street is in a conservation area, and whether that area has an Article 4 direction. The status of a conservation area, and any direction that goes with it, is a matter of public record, so none of this has to be guessed. If you are not sure of the answers, the planning service at your council can confirm them for an address, and the quickest route is often to ring them with the postcode.

We put the same questions to your address before ordering. Where no application is needed, the sun tunnel goes ahead as permitted development. Where one is needed, we say so at the start, and the order waits for the council's decision.

The full service is described under sun tunnel installation in Leeds, and the guide to how a sun tunnel is installed describes the job once permission is settled. To talk through your own address, ring 0113 436 0654 and give us the postcode.