The short answer
Often not, but it depends on the house and on how tall the lantern stands. A roof lantern on a single-storey extension is frequently covered by permitted development, so long as the whole extension stays within its height limits. A lantern added to an existing flat roof is judged differently, because it rises well above the roof surface. Flats, listed buildings and many conservation areas need a check or a full application first.
Planning permission is separate from Building Regulations. Even where no application is needed, a lantern is building work and is notified to Building Control, which we handle.
The 150mm rule and why lanterns meet it badly
Rooflights on a house normally rely on Class C, Part 1, Schedule 2 of the General Permitted Development Order. That right holds while the unit stands no more than 150mm clear of the roof slope and its top stays below the highest point of the roof.
A flat rooflight or a roof window sits within that limit. A roof lantern does not: it is a glazed structure with a ridge, and even a modest one stands several hundred millimetres above its upstand. Added to an existing roof on its own, it is likely to project further than 150mm, so Class C does not cover it. That is a difference between lanterns and other rooflights, and it is the reason this question comes up so often.
That does not mean the answer is no. It means the lantern has to be judged under a different part of the rules, or by the council directly.
When the lantern is part of an extension
The more common route is a single-storey rear extension built under the permitted development rights for enlarging a house, with the lantern designed in from the start. In that case the lantern is part of the extension, and what counts is whether the finished extension, lantern included, sits within the limits for height, depth and boundaries.
- Height. A single-storey rear extension has a maximum height, and where it stands close to a boundary the eaves are limited further. The top of the lantern counts toward the overall height.
- Materials. The extension's external materials are expected to match the existing house, and the lantern frame is part of the exterior.
- Other limits. Depth, the share of the garden covered and any earlier extensions all count towards the same allowance.
Where a lantern is added later to an extension that was already built, the lantern is a new alteration of its own and the same question arises again. If you are unsure, ask the local planning authority, or apply for a lawful development certificate, which gives you written confirmation that the work is lawful.
Where permitted development does not apply
Some homes do not have the householder rights described above, or have them restricted. Check these before anything else.
- Flats and maisonettes are outside householder permitted development, so a lantern on the flat roof of a flat usually needs an application.
- Listed buildings require listed building consent before any external alteration, and a lantern is something a conservation officer will examine closely.
- Conservation areas allow Class C, but an Article 4 direction can take that right away. In Exeter the St Leonards, Southernhay and Topsham areas are designated conservation areas, and any council may apply a direction to a particular street, so look at the local list.
- National parks. Dartmoor and Exmoor are Article 2(3) land, where some rights are restricted. Check with the national park authority.
- Houses with rights removed, for example by a planning condition on a new-build estate or a previous permission.
For the general picture in Devon, see our guide to rooflights, planning permission and Building Regulations, and our answer on conservation rooflights and planning for older buildings.
Who decides, and how to ask
The local planning authority decides. In and around Exeter that is usually the city council, East Devon, Mid Devon or Teignbridge District Council, with Dartmoor National Park Authority inside the park. The right body depends on the address, and your quote will name it.
You have three ways to settle it, in rising order of formality:
- Read the Planning Portal guidance and the council's own pages for your house type.
- Ask the council's duty planner for an opinion, which is informal and not binding.
- Apply for a lawful development certificate or a householder application, which is the written route and the one to take if the house is borderline.
Plans for the application are drawn from a survey: roof and ceiling dimensions, the lantern's height above the upstand and the position on the roof. We take those measurements, and the finish schedule written with the quote records the same details.
Building Regulations are still needed
A lantern over a new opening is building work whatever the planning position. The rafters or joists are trimmed, so it is a structural alteration, and the glazing must also satisfy Part L of the Building Regulations. Approval or notification goes to Building Control before the work starts, and we handle that. Our answer on whether skylights need Building Regulations approval sets out what it covers.
The planning result affects the build too. A council may ask for a particular frame colour or a lower profile, and a lantern designed to be lower, with a shallower pitch and smaller upstand, may be the way to keep a borderline scheme inside the rules.
What to do next
Do this before the order is placed, and keep any council reply in writing, because a lantern is made to measure and cannot easily be changed once it is made.
Before you order a lantern, find out whether the house has permitted development rights and what the local authority says about height. Then ask for a quote. We survey the roof, ceiling and upstand height, write a finish schedule and, where your scheme is borderline, give you the figures you need for the council. The wider roof lantern installation page covers the whole job from specification to finish inside.
If your new lantern goes on an existing flat roof, our answer on whether a roof lantern can go on an existing flat roof covers the structure and the upstand.