Your boundary decides more than your budget
Ask an Aberdeen planner how far back you can build and the first question back is what kind of house you live in. The council's Householder Design Guide (Aberdeen Planning Guidance, 2023) sets hard numbers by house type. On a semi, a single-storey addition running along the shared boundary stops at 4 metres. On a terrace it stops at 3. Go up a storey on a semi and the projection along that boundary is generally held to 3 metres, while on a terrace anything over one storey on the mutual boundary will normally be refused.
Detached houses get judged site by site. Two other limits apply to everyone. The house as extended mustn't cover more than twice the footprint of the original, and no more than half of the front or rear garden can end up built on.
About a third of the city's homes are semis or terraces (2017 housing needs study). Flats make up 55%, and a flat has no permitted development right to extend at all.
What Class 1A and 1B let a house owner build
Forget the English 6 and 8 metre figures. Scotland works to its own order, explained in the Scottish Government's Circular 1/2024. A single-storey extension (Class 1A) can go ahead without a planning application if it stays under 4 metres high with eaves no higher than 3 metres. Where any part comes within a metre of a boundary, it can't run more than 3 metres past the rear wall of a terrace house, or 4 metres on any other house.
Anything taller than one storey (Class 1B) has to keep every part at least 10 metres from the boundary. On most city plots that rules it out. Neither class lets you build forward of the front of the house, or of a side wall facing a road. Neither applies in a conservation area.
Building standards is a separate question. Speak to the building standards team before you start, because a warrant is normally needed for an extension and building without one can lead to a fine and an order to take the work down.
Permission and permitted development. Check the boundary distances first, then check the eleven conservation areas. If either test fails, it's a planning application, judged against the council's 2023 guide.
Single-storey rear. The one most Aberdeen owners can build under Class 1A, provided the depth near the boundary stays within 3 metres on a terrace or 4 metres elsewhere.
Kitchen. Plan the light before the floor area. If a neighbour's window sits at right angles to your new wall, the council will test it with its 45-degree daylight check.
Open-plan. Knocking through a solid granite back wall needs a structural engineer's design. The warrant application has to include a certificate of design or calculations for structural work, so get the steel sized before the drawings go in.
Two-storey. Almost never permitted development here because of the 10 metre boundary rule. The guide treats it as possible on a detached house of two or more storeys, harder on a semi, and not normally acceptable on a grouped or non-traditional terrace.
Wrap-around. Class 1A doesn't cover anything forward of a side elevation that fronts a road, which catches corner plots where the side of the house faces the street.
Side return. Only possible where the house actually has a strip of ground beside it. Where there is one, a side addition that doesn't project past the rear wall isn't caught by the Class 1A depth test.
Ground floor bedroom. Often the best answer in a two-storey semi where stairs have become a problem. Bedroom windows looking straight at the neighbours should be 18 metres or more from theirs, or the planners will look closely at screening and levels.
Home office. A detached garden building must stay subordinate to the house, and the council generally won't allow two storeys or put one in a front garden. Attaching the office to the house is usually the simpler consent.
Cost and value. We won't print a figure. Matching granite, slate roofs, engineer's fees and the warrant fee (which rises with the value of the work) all move it. Three quotes from builders who have seen the site will tell you more.
Floods, gravel and green belt around the edges of the city
Most of the city is covered by the five flood risk areas named in the North East local flood risk management plan: Bridge of Don, Denmore, Deeside, Peterculter and Westhill. Planners use SEPA's maps and their own flood engineers to decide if a flood risk assessment is needed. A drainage impact assessment comes in at 100 square metres of extension or hard surfacing, or for something smaller in an area affected by flooding. A house extension doesn't need its own SuDS scheme.
The ground varies more than the granite suggests. The British Geological Survey records sand and gravel from Bridge of Don up towards Newburgh, and under the Dee floodplain below Peterculter there's waterlogged gravel averaging over 9 metres deep beneath thin clayey alluvium. Much of that gravel was dug out and later built over. A trial pit before the foundation design is cheap insurance.
On the green belt fringes, the Local Development Plan 2023 (Policy NE1) asks that new building is small-scale and subordinate to what's already there, extensions to houses included. There's no set percentage.
Where these facts come from
- Scottish Government: Planning Circular 1/2024, Classes 1A, 1B and 1C
- Aberdeen Planning Guidance 2023: Householder Design Guide
- Aberdeen City Council: Supplementary Guidance, Flooding, Drainage and Water Quality
- Aberdeen City Council: conservation areas
- Aberdeen City Council: building warrant application guidance
- mygov.scot: building standards if you do the work yourself
- British Geological Survey: sand and gravel resources, Sheet 77 Aberdeen
- Aberdeen City and Shire HNDA 2017 (dwelling types)
- Aberdeen City Council planning register
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Questions people in Aberdeen ask
I live in a semi-detached granite house. How deep can my kitchen extension go along the shared boundary?
Aberdeen's guide limits a single-storey addition along the shared boundary of a semi to 4 metres. Under Class 1A, the same 4 metres is the permitted development limit where any part comes within a metre of the boundary. Outside a conservation area, and under 4 metres high, you may not need a planning application. A warrant is a separate question.
Our house is in Ferryhill conservation area. Can we build anything without permission?
No extension, porch or outbuilding rights apply in a conservation area under the Scottish order, so plan on a full application. The council also won't accept a front extension on a house that forms part of an established building line there.
Can I add a porch with a downstairs toilet?
A porch of up to 3 square metres, under 3 metres high and at least 2 metres from the road boundary, can be permitted development. Aberdeen's guide says porches shouldn't contain extra rooms such as a toilet or shower room. For that you're really looking at a small front or side extension and a planning application.
We extended years ago. Does that count against a new extension?
Yes, potentially. The limit of twice the original footprint and the 50% garden rule count everything built since the house was new. Older approvals granted before the current guide aren't treated as a precedent either.