Cost guide · Scotland · September 2026
House extension cost in Scotland (2026)
A mid-range single-storey rear extension of 25 m² in Scotland costs about £60,000 to £74,000 for the building work, including VAT (£2,400 to £3,000 per m²), about 5% below the UK average outside London of £63,000 to £78,000. A building warrant for that extension costs about £950 to £1,120, set by the value of the work excluding VAT, and a householder planning application costs £371 if you need one. With a measured survey, design, a structural engineer, the warrant and a 15% contingency, budget about £75,000 to £97,000.
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Extension prices in Scotland
Building work in Scotland costs about 5% less than the UK average in our model, which uses one Scotland-wide price level. Prices still vary from place to place, so treat these as planning figures and get at least three written quotes.
| Type | Budget | Mid-range | Premium |
|---|---|---|---|
| Single-storey rear (25 m²) | £48,500 to £60,000 | £60,000 to £74,000 | £77,000 to £94,000 |
| Double-storey (40 m²) | £68,500 to £86,500 | £86,500 to £109,000 | £114,000 to £141,000 |
| Wraparound or side return (30 m²) | £65,000 to £78,500 | £78,500 to £99,000 | £103,000 to £127,000 |
Budgets by size, with the building warrant
A building warrant is charged on the value of the building work excluding VAT, not the floor area, so it rises with the size and cost of the extension.
| Floor area | Building work | Building warrant | Budget with fees and 15% contingency |
|---|---|---|---|
| 15 m² | £36,000 to £44,500 | £780 to £865 | £47,000 to £63,000 |
| 20 m² | £48,000 to £59,500 | £865 to £950 | £61,000 to £80,000 |
| 30 m² | £72,000 to £89,000 | £1,035 to £1,205 | £88,500 to £114,000 |
| 40 m² | £96,000 to £119,000 | £1,205 to £1,375 | £116,000 to £149,000 |
Each figure is rounded on its own, so a row can differ from its parts by a few hundred pounds. Budgets include a measured survey, design drawings, a structural engineer and the warrant. A planning application is extra if you need one.
Fees and approvals in Scotland
For a 25 m² single-storey extension, mid-range, at Scottish prices:
| Fee | Typical cost | Notes |
|---|---|---|
| Measured survey | £600 to £1,800 | |
| Design drawings (planning and building warrant) | £3,600 to £6,000 | |
| Structural engineer | £900 to £3,000 | |
| Building warrant (Scotland, national fee scale) | £950 to £1,120 | Set by the value of the building work excluding VAT, not floor area: £950 for £40,001 to £50,000 of work, £1,375 for £90,001 to £100,000 (scale from 1 April 2026) |
| Householder planning application (Scotland) | £371 | Only if your project needs planning permission. Scottish householder fee, 2026. Not in the budget figures above. |
There is no party wall surveyor line: the Party Wall etc. Act 1996 does not apply in Scotland.
Loft conversion costs in Scotland
| Type | Building work | Building warrant |
|---|---|---|
| Rooflight (Velux) | £31,000 to £40,000 | £780 to £865 |
| Rear dormer | £53,500 to £66,000 | £950 to £1,035 |
| Hip-to-gable (with rear dormer) | £62,500 to £77,500 | £1,035 to £1,120 |
| Mansard | £74,000 to £97,000 | £1,120 to £1,290 |
Design and a structural engineer come on top, as for an extension, plus a 15% contingency. See loft conversion costs for what each type involves and how to tell which one a quote is for.
Planning, building warrants and neighbours
Planning permission. Scotland has its own permitted development rules for householders. A single-storey extension can usually go ahead without planning permission if its eaves are no higher than 3 m and it is no higher than 4 m overall, it does not more than double the ground the house covers, and new building covers no more than half the rear garden. Within 1 m of a boundary it can project no more than 3 m beyond the back of a terraced house, or 4 m for other houses. A dormer can be added on a roof slope that is not on the front of the house, or on a side facing a road, if it is at least 10 m from the boundary that slope faces, no wider than half the roof, at least 0.3 m from the roof's edges and no higher than the existing ridge. There are no householder permitted development rights for these extensions or roof alterations in a conservation area. The full rules are in Planning circular 1/2024. If you need planning permission, a householder application costs £371 (circular 1/2026), and a certificate of lawfulness, which proves no application is needed, costs half that.
Building warrant. Almost every extension and loft conversion needs a building warrant from your council’s building standards department, and you must not start work until it is granted. When the work is finished you submit a completion certificate. The fee comes from a national scale based on the value of the work excluding VAT (scale from 1 April 2026); see mygov.scot for how to apply.
Neighbours. The Party Wall etc. Act 1996 does not apply in Scotland. If you are building on or near a shared wall, check your title deeds and ask your designer or a solicitor how it is handled.
VAT. Builders charge 20% VAT on extensions and loft conversions in Scotland, as elsewhere in the UK. Our prices include it.
Questions people ask
How much does an extension cost in Scotland?
About £60,000 to £74,000 for a mid-range single-storey rear extension of 25 m², including VAT, before fees (September 2026 prices). That is £2,400 to £3,000 per m². Small extensions cost more per m², and two-storey extensions less.
How much is a building warrant for an extension in Scotland?
The fee comes from a national scale set by the value of the building work excluding VAT. For a mid-range 25 m² extension costing £60,000 to £74,000 including VAT (about £50,000 to £62,000 before VAT) it is about £950 to £1,120 (September 2026 prices). The scale starts at £215 for work up to £5,000, reaches £1,375 for work of £90,001 to £100,000 and rises further above that.
Do I need planning permission for an extension in Scotland?
Not always. A single-storey extension is usually permitted development if it is not in front of the house or beside a road, stays within height limits (3 m to the eaves, 4 m overall), does not more than double the original footprint, leaves at least half the rear garden free and, within 1 m of a boundary, projects no more than 3 m from a terraced house or 4 m from other houses. These rights do not apply to flats or in a conservation area. Check with your council's planning department, or apply for a certificate of lawfulness if you want proof.
How much does a loft conversion cost in Scotland?
About £53,500 to £66,000 for a mid-range rear dormer of about 30 m², including VAT, before fees, plus a building warrant of about £950 to £1,035 (September 2026 prices).
Sources
Prices come from the same cost model as the rest of Estiquote at the Scotland regional factor; read how Estiquote estimates work. Official sources checked 3 October 2026: