Permitted development in Scotland: the rules for extensions
Many single-storey extensions in Scotland can be built without a planning application. The rights that allow it are set out in two classes, 1A and 1B, and they are not the same as the rules south of the border.
Class 1A: single-storey extensions
| Test | The limit |
|---|---|
| Position | Nothing in front of the principal elevation, or of a side elevation that faces a road |
| Depth near a boundary | Where it comes within 1 m of a boundary, no deeper than 3 m past the back wall on a terrace, or 4 m for other houses |
| Eaves | No higher than 3 m |
| Overall height | No part higher than 4 m |
| Footprint | The extended house may cover no more than twice the ground the original house covered |
| Garden | Counting outbuildings too, at most half of the front garden, or of the back one, built over (the curtilage) |
| Conservation areas | The class does not apply |
A summary of the limits in the Scottish Government's householder circular. The wording of the Order itself decides a borderline case.
What permitted development means in Scotland
Permitted development is planning permission granted in advance by Scottish Ministers for small, predictable changes to a house. If your extension fits inside the limits, you do not apply to the council for planning permission. The limits were rewritten for householders in 2012 and are explained in Circular 1/2024.
Depth is the big difference from England. There is no blanket figure for how far back you can build. The 3 m and 4 m limits bite only on the parts of the extension that sit within a metre of a boundary. Set the whole room more than a metre in from each side and the depth is governed by the footprint and garden tests instead.
Class 1B: two storeys and above
An extension of more than one storey is permitted only if every part of it stands at least 10 m from the boundary of the plot. It cannot be taller than the existing house, cannot sit in front of the principal elevation, and has to pass the same footprint and garden tests as a single storey.
Ten metres rules out most houses on ordinary streets. A two-storey extension on a semi or a terrace nearly always means a householder planning application, however it is built.
Where the rights do not apply
Flats have no extension rights at all, and that includes tenement flats, four-in-a-block cottage flats and maisonettes. Houses in conservation areas are excluded from both classes. Any work to a listed building also needs listed building consent, however small.
Newer estates are the quiet trap. The planning permission for the estate sometimes carries a condition removing permitted development from every plot, and the only way to find out is to read that decision notice on the council's planning portal. Check before you pay for drawings.
What the limits mean for a factory-built room
A flat-roofed module or panel build is usually around 3 m from ground to the top of the roof edge, so the eaves test is tight but achievable. Heights are measured from the lowest ground beside the extension. Where the garden drops away from the back wall, a floor set level with the kitchen can push the far end over 3 m, and the design has to be checked on a section drawing, not on plan.
Module widths are set by what a lorry can carry, so a design is often stretched or trimmed by a few hundred millimetres to suit the factory. Make sure the final manufactured size is the one tested against Class 1A, particularly beside a boundary.
Proving it, and what still applies
You do not have to tell the council you are using permitted development. If you want it in writing, apply for a certificate of lawfulness for the proposed work; solicitors often ask for one when the house is sold. Our post on the certificate of lawfulness explains the application.
Planning is only half of it. Almost every extension still needs a building warrant before work starts on site, and being exempt from planning makes no difference to that.
Not sure whether your extension fits? Send the postcode and a rough size and a builder can tell you at the survey.
Get a quoteQuestions people ask
How deep can a Scottish extension go before it needs planning?
No one figure applies. The part of a single-storey extension that sits within a metre of a boundary may project 3 m on a terrace, measured out from the back wall, or 4 m on a semi or detached house. Further from the boundary, the limits are the 4 m height, the doubled footprint and half the rear garden.
Is permitted development the same in Scotland and England?
No. Scotland has its own Order and its own classes. There is no prior approval scheme for larger rear extensions, and two-storey extensions must be 10 m from every boundary.
Do I need a building warrant if I do not need planning permission?
Yes, in nearly every case. Planning and building standards are separate systems, and an extension that is permitted development still needs a warrant before work starts.
Can I extend a flat under permitted development?
No. The extension classes apply to houses only. A flat, including a ground-floor flat in a four-in-a-block, needs planning permission for any extension.
Get a quote for an extension that fits the rules
Three short screens: the postcode, four questions about the room, and how to contact you. There is no charge and no obligation to go ahead.
We don't build extensions ourselves. We match your enquiry with one firm that works in your area, name it to you, and send your details over only once you agree.
Your enquiry is in.
- A call or email from us, usually inside a working day, names a firm that is active in your part of Scotland.
- Your details stay with us until you say they can be sent across.
- Once you agree, the firm books a visit, looks at the house and the access, and prices the room. We send no marketing.