Are rooflights allowed in Dartmoor National Park?

Within the boundary, planning applications go to Dartmoor National Park Authority. Outside it, the same town may fall under Teignbridge, West Devon or South Hams. Moretonhampstead and Chagford sit inside the park. Places such as Bovey Tracey, Ashburton and Buckfastleigh are on the edge, and some properties are in and some are out, so check the boundary for your own address before assuming either way. The authority's website has a map, and a phone call or email to its planning team settles it.

On a house, the General Permitted Development Order covers rooflights in Class C of Part 1, Schedule 2. Three conditions apply. The unit may stand no more than 150mm proud of the roof slope. Its top edge may not rise above the ridge or other highest point of the roof. A rooflight in a side-facing slope must be obscure-glazed and fixed shut, unless the part that opens sits over 1.7m up from the floor.

National parks are what the rules call Article 2(3) land, and some permitted development rights are restricted there, such as cladding and side extensions. Rooflights under Class C are not one of the restricted rights, which is why a modest rooflight on an ordinary Dartmoor house often needs no application. Even so, the rights come with exceptions, and they do not apply to flats, maisonettes or buildings that are not houses.

Several things on Dartmoor take a rooflight out of permitted development.

• Listed buildings. Any external alteration, including a rooflight, needs listed building consent. Many Dartmoor farmhouses, longhouses and cottages are listed.
• Article 4 directions. A direction can remove Class C locally, for instance in a conservation area within a village.
• Conditions on the original permission. A barn conversion, or a house built under a planning consent, may have had its permitted development rights withdrawn in the original decision notice. Check the paperwork.
• Properties that are not dwellinghouses, such as holiday lets, flats and agricultural buildings.

If any of these apply, the authority will look at the rooflight against the character of the building and the landscape, and will expect a conservation-style unit, small and flush, in a position that does not dominate the roof.

Dartmoor roofs are of granite, slate and sometimes thatch, set in open country where they can be seen from a long way off. Officers are generally concerned about reflection, scale and position. A slim, flush-fitting conservation rooflight in a dark frame, on a rear or less visible slope, is much easier to agree than a large modern unit on the main elevation.

The park is also an International Dark Sky Reserve, so night-time light matters locally. That is a consideration for lit rooms with big, uncovered glass, and a blind or a smaller rooflight can help. It is a reason to think about the size and the glazing, not a ban. For help judging size, see our answer on what size conservation rooflight suits a cottage.

Dartmoor housing is varied. There are granite longhouses with deep walls, Victorian terraces in the market towns, cob and thatch on the valley sides, and plenty of barn conversions with their own planning history. The roof build matters to the rooflight as much as the paperwork does. Granite houses often have thick, uneven rafters and a roof of slate hung on laths, while the ceilings below may be plaster on lath, and cutting an opening through them wants care.

That is why a survey comes before the application. If the authority asks for drawings, a measured rafter layout and a section of the roof build give them what they need to agree a position. If consent is not needed, the same survey tells you what the roof will take. Both go into the finish schedule, which also notes the shape of the lining and how the plasterwork will blend into the ceiling around it.

Thatch deserves a mention. A rooflight in a thatched roof is possible but limited, and a thatcher dresses the roof around the frame. Read can a rooflight go in a thatched roof before you plan one on a moorland cottage.

Open moorland brings wind, driving rain and cold. A rooflight here should be chosen for its insulation as much as its looks, so a double glazed unit with a warm-edge spacer is a sensible baseline, and the frame and flashing must be fitted to cope with exposure. It also has to meet Part L, whatever the planning position, so the glazing choice is not only a matter of taste.

Planning and Building Regulations are separate questions. Forming a fresh opening in a roof that is already built counts as building work, because the rafters are trimmed and the finished window has to satisfy Part L. Building Control approval is needed whether or not planning is. Where the work is notifiable, we make the notification for you. Swapping an entire rooflight, frame included, is notifiable as well. Swapping just the sealed glazing unit is the exception and is not.

Work out the order of questions: first, is the building listed? Second, is there an Article 4 direction or an old planning condition? Third, which authority covers the address? If the answers are no, no and Dartmoor National Park Authority, a modest rooflight is usually permitted development. If you are unsure, ask the authority in writing before you order, and keep the reply with your paperwork.

For a listed building, read conservation rooflights for listed buildings. For the position in conservation areas, see conservation rooflights in Devon conservation areas, and for the direct question on consent, do conservation rooflights need planning permission. When you are ready to talk about a roof on the moor, ask for a quote and we will survey it, including the ceiling below, and write the finish into your schedule.