SCOTTISH PLANNING GUIDE · MPS INTERIORS LTD · UPDATED JULY 2026

House extensions in Scotland: permitted development limits & beyond

Scotland's permitted development rules are generous for rear extensions — if you know the exact numbers and where the rights switch off.

Planning permission

Not if you stay in the limits

Single-storey rear extensions within Class 1A limits are permitted development — outside them, or in conservation areas, you apply.

Building warrant

Yes, almost always

Foundations, structure, insulation and drainage all have to meet Scottish standards, whatever the planning position.

The permitted development numbers (single-storey rear)

Maximum height 4 metres; eaves maximum 3 metres.
Within 1m of a boundary: projection from the original rear wall limited to 4m (detached/semi) or 3m (terraced).
Extension must be to the rear — not forward of the principal elevation, nor a side elevation facing a road.
Total additions must not exceed the original footprint of the house.
All development must cover less than half the front/rear garden area.
No Class 1A rights in conservation areas. Listed buildings need consent for anything affecting character. Flats have no householder PD rights at all.

"Original" means the house as first built (or as it stood in 1948) — previous extensions, even by former owners, count against your allowance. This catches people out constantly.

If you need to apply — don't fear it

A planning application isn't a punishment; it's a design conversation. Householder applications target a ~2-month decision. Good drawings, materials that respect the street, and early neighbour conversations get most sensible schemes through. Where a design pushes limits, a pre-application enquiry with the council flushes out issues before you commit (some councils charge a modest fee for this).

Costs, honestly

Scottish single-storey extensions typically run £2,000–£3,000+ per m² built and finished, depending on spec, glazing, groundworks and access. A 20m² kitchen extension therefore sits realistically around £40k–£60k+ — be wary of quotes far below that with no itemisation. Timescale: 8–14 weeks on site for most single-storey schemes, plus design and consents beforehand.

📍 Case study: Perthshire villa — kitchen-diner extension

A 3.8m rear extension to a stone villa: within PD limits (under 4m projection and height, rear-facing, footprint fine) so no planning application was needed — but the conservation-area check came first, and this house sat just outside the boundary. Warrant covered foundations near mature trees, steel goalpost frame for the glazed opening, and insulation to current standards. Twelve weeks on site.

Lesson: the conservation-area map, not the postcode, decides your rights — we check it before drawing a single line.

Asked in the groups

"Do neighbours get a say if it's permitted development?"

No neighbour notification applies to genuine PD — that's the point. But boundary walls, shared drains and access for the build are still civil matters, and falling out with neighbours over mess costs more than tea and a heads-up. If you apply for permission, neighbours are formally notified and can comment.

"Can I build right up to the boundary?"

Planning-wise, within 1m of the boundary triggers the tighter projection limits. Warrant-wise, fire spread rules apply near boundaries. Practically, you also need to build and maintain it — think about gutters, foundations, and your neighbour's wall.

"Is a two-storey extension permitted development?"

The rules are much tighter and most two-storey schemes in practice need planning permission. Budget for an application and design it properly — a good two-storey extension is transformative but it's a full planning job.

Extension on the horizon?

Free home visit: we'll measure, check your PD position and conservation status, and give you honest numbers.

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General guidance, not professional advice — limits summarised from Scottish Government Circular 1/2024 (householder permitted development rights); confirm your property's position with your council. Sources: gov.scot Circular 1/2024; mygov.scot.