Can I do a loft conversion without planning permission?
Usually, if the dormers add no more than 40 m³ of roof space on a terraced house or 50 m³ on a detached or semi-detached one, and none is on the front slope facing the road. Add your dormers and watch the allowance fill up.
1. Is the house on protected land? (optional)
Dormers aren't permitted development in conservation areas, National Parks and other protected land.Your postcode stays in your browser. We only fetch the data for its first half (for example "SW1A"). See the map and everything published for this postcode
2. Your loft
This is an example: change the figures to yours.
Likely permitted development, with things to check
Everything we can measure fits. Read the 3 points marked Check below before you build.
This is guidance, not legal advice. For certainty, apply to your council for a Lawful Development Certificate.
Checked against each rule
- CheckNot on protected landDormers aren't permitted development on protected land, which we can't rule out for your address. Enter your postcode, or answer the question.Source:
Schedule 2, Part 1, Class B, paragraph B.1(f)
“the dwellinghouse is on article 2(3) land”
- FitsExtra roof space: max 50 m³ (detached or semi-detached)Dormer 1: about 15.4 m³. Total about 15.4 m³. Limit: 50 m³. These are estimates from your measurements: measure precisely, or ask your designer, if you're close.Source:
Schedule 2, Part 1, Class B, paragraph B.1(d)(ii)
“the cubic content of the resulting roof space would exceed the cubic content of the original roof space by more than— (i) 40 cubic metres in the case of a terrace house, or (ii) 50 cubic metres in any other case”
- FitsNot on the front roof slope facing a roadAt the back, or on a slope that doesn't face a road.Source:
Schedule 2, Part 1, Class B, paragraph B.1(c)
“any part of the dwellinghouse would, as a result of the works, extend beyond the plane of any existing roof slope which forms the principal elevation of the dwellinghouse and fronts a highway”
- FitsNo higher than the existing roofThe dormer stays below the ridge.Source:
Schedule 2, Part 1, Class B, paragraph B.1(b)
“any part of the dwellinghouse would, as a result of the works, exceed the height of the highest part of the existing roof”
- FitsSet back from the eaves: at least 0.2 m, so far as practicableYours: 0.3 m. Minimum: 0.2 m.Source:,
Schedule 2, Part 1, Class B, paragraph B.2(b)(i)(bb)
“the edge of the enlargement closest to the eaves of the original roof is, so far as practicable, not less than 0.2 metres from the eaves, measured along the roof slope from the outside edge of the eaves”
Schedule 2, Part 1, Class B, paragraph B.2(b)(i)(aa)
“the eaves of the original roof are maintained or reinstated; and”
- FitsNo overhang beyond the outside wallsIt doesn't overhang the outside face of the walls.Source:
Schedule 2, Part 1, Class B, paragraph B.2(b)(ii)
“no part of the enlargement extends beyond the outside face of any external wall of the original dwellinghouse”
- FitsSide windows obscure-glazed and high-openingNo windows in a side wall or side roof slope.Source:
Schedule 2, Part 1, Class B, paragraph B.2(c)
any window inserted on a wall or roof slope forming a side elevation of the dwellinghouse must be— (i) obscure-glazed, and “non-opening unless the parts of the window which can be opened are more than 1.7 metres above the floor of the room in which the window is installed”
- FitsMaterials look similar to the houseThey must look similar to the existing house: a visual judgement.Source:
Schedule 2, Part 1, Class B, paragraph B.2(a)
“the materials used in any exterior work must be of a similar appearance to those used in the construction of the exterior of the existing dwellinghouse”
- FitsNo balcony, veranda or raised platformNone planned.Source:
Schedule 2, Part 1, Class B, paragraph B.1(e)(i)
“the construction or provision of a verandah, balcony or raised platform, or”
- FitsNo storeys added under the upward extension rightsNo storeys have been added on top of the house under Class AA.Source:
Schedule 2, Part 1, Class B, paragraph B.1(h)
“the existing dwellinghouse has been enlarged in reliance on the permission granted by Class AA (enlargement of a dwellinghouse by construction of additional storeys)”
- FitsThe house wasn't created under permitted developmentYou said it wasn't.Source:,
Schedule 2, Part 1, Class B, paragraph B.1(a)
“permission to use the dwellinghouse as a dwellinghouse has been granted only by virtue of Class G, M, MA, N, P , PA or Q of Part 3 of this Schedule (changes of use)”
Schedule 2, Part 1, Class B, paragraph B.1(g)
“the dwellinghouse is built under Part 20 of this Schedule (construction of new dwellinghouses)”
- CheckNo Article 4 direction removes these rightsEnter your postcode above and we'll check what your council has published.Source:
Article 4(1)
“may make a direction under this paragraph that the permission granted by article 3 does not apply to— (a) all or any development of the Part, Class or paragraph in question in an area specified in the direction; or (b) any particular development, falling within that Part, Class or paragraph, which is specified in the direction”
- CheckNo planning condition removes these rightsWas your house built in the last 30 years, or on an estate? A planning condition may have removed these rights. Check the council's planning register.Source:
Article 3(4)
“Nothing in this Order permits development contrary to any condition imposed by any planning permission granted or deemed to be granted under Part 3 or Part 13 of the Act otherwise than by this Order”
3. Has a planning condition removed your loft rights?
Was your house built in the last 30 years, or on an estate? Planning conditions may have removed these rights. When a council grants planning permission for new houses, it can attach a condition that removes some or all permitted development rights, for example extensions, outbuildings or fences. This is common on newer estates. If there is such a condition, the rights in this checker do not apply and you need planning permission. Open data does not record these conditions, so this tool cannot check them for you. The 30 years is a prompt, not a legal cut-off. A condition on a permission of any age still applies.
How to check
- Find your council's online planning register (search for the council name and "planning applications search").
- Search by your address, your road name or the estate name for the permission that allowed the house to be built. On an estate this is usually the developer's application, which may list many plots.
- Open the decision notice and read the conditions. Look for any condition that mentions the General Permitted Development Order, "permitted development", or Part 1 (Class B: roof enlargements) of Schedule 2, or that says no dormers or other roof extensions may be put up without permission. A condition that only removes other rights (for example fences or outbuildings) doesn't affect this project.
- Also check any later permission for your house, such as an earlier extension. Its conditions can remove rights too.
- If the permission is old and not online, ask the council's planning department, or look at the local authority search in your purchase documents.
- If you are still unsure, ask the council or apply for a Lawful Development Certificate.
Loft conversions: what people ask
Do I need planning permission for a loft conversion?
Usually not, if it adds no more than 40 m³ of roof space on a terraced house or 50 m³ on a detached or semi-detached house, isn't on the front slope facing the road, and doesn't go above the ridge.
Dormers aren't permitted development in conservation areas, National Parks, the Broads, National Landscapes or World Heritage Sites. A loft conversion with only rooflights inside the existing roof is simpler again.
How big is 40 m³ or 50 m³ of roof space?
It's the extra volume your dormers (and any hip to gable) add to the roof, plus any roof additions made since 1948. A box dormer adds about half its width × height × depth: for example a dormer 4 metres wide, 2.2 metres high and 3.5 metres deep adds about 15.4 cubic metres.
Can I put a dormer on the front of my house?
Not under permitted development if the front roof slope forms the principal elevation and faces a road. Rear and side dormers are fine within the other limits.
How far from the eaves must a dormer be?
At least 0.2 m, so far as practicable, measured along the roof slope from the edge of the eaves. The original eaves must be kept, apart from a hip to gable.
Do side windows in a loft need to be obscure glass?
Yes. Any window in a side wall or side roof slope must be obscure-glazed, and can only open more than 1.7 m above the floor of the room.
Do rooflights need planning permission?
Usually not: they can stick out no more than 0.15 m from the roof slope and can't go above the ridge. Rooflights in a side slope must be obscure-glazed.
The clauses behind this checker
- The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 1, Class B (roof enlargements) and Class C (other roof alterations), on legislation.gov.uk. Text in force from 27 August 2026, checked 14 October 2026.
- The roof space figures are estimates from your measurements, using standard geometry: a box dormer adds half its width × height × depth, and a hip to gable adds width × hip depth × height ÷ 6. They aren't in the law; the law limits the increase in the roof space's cubic content.
Next steps for your house
- Check my addressCheck whether your postcode is on protected land, where dormers need planning permission.
- Fence, wall and gate height checkerHow high a fence, wall or gate can be: next to a road or not, on a slope, with trellis on top.
- Garden room and outbuilding checkerHeight near the boundary, roof shape, eaves, how much of the garden it covers, and use.
- Rear and side extension checkerSingle and two-storey, the larger home extension route, eaves near a boundary.
- Heat pump checkerAir, ground and water source, including the May 2025 changes.