House Extensions in Glasgow

An extension adds floor space at ground level, and the most common kind is a single-storey extension to the rear. A 20 to 30 m² one is put at £44,000 to £60,000 in published UK figures. Many don't need planning permission, but nearly all need a building warrant.

We don't build extensions. We pass your enquiry to one independent local firm, who looks at the house and quotes you. Free to use, no obligation.

What it usually costs

Published UK prices for a house extension. Guide figures, not quotes.
Type	Per m²	Typical total
Single storey (20–30 m²)	£1,700–£1,900	£44,000–£60,000
Double storey (40–60 m² total)	£1,500–£1,800	£80,000–£120,000
Double plus loft (60–80 m² total)	£1,300–£1,750	£100,000–£160,000

Source: MyJobQuote house extension costs (19 October 2026). These are UK figures, not Glasgow ones. MyJobQuote puts the average for a standard single-storey extension at about £52,000.

The per-square-metre rate falls as the job grows, but the total doesn't. What moves it most: the foundations and ground conditions, how much of the back wall comes out, the kitchen or bathroom going inside, and how you finish the roof. Glazing can add a lot. Ask for a price with and without it.

Planning and building warrant

Building warrant. mygov.scot (24 November 2025) lists extending your home as needing one, along with removing load-bearing walls. You must have it before work starts.

Planning. Circular 1/2024 (28 May 2024) sets out what's permitted development on a house. Neither class applies in a conservation area or to a flat.

The main limits, in short.
Limit	Single storey (Class 1A)	More than one storey (Class 1B)
Position	Not forward of the front wall, or of a side wall that fronts a road	The same
Near a boundary	Within 1 m of one: up to 3 m beyond the rear wall on a terrace, 4 m otherwise	Nothing within 10 m of any boundary
Height	4 m overall, eaves 3 m	No higher than the existing house
Size	Can't more than double the ground the original house covers, or fill more than half of that front or rear garden	The same

The 10-metre rule means most two-storey extensions on ordinary suburban plots need an application. It's a straightforward process, though it adds time and a fee. Our drawings page explains what goes in.

Listed building consent may also apply. So may a condition from an earlier planning permission, so it's worth asking the council if you know of one.

Before you ask for prices

Common questions

Is a loft conversion cheaper than an extension?

Going by published figures, often yes. A Glasgow dormer is put at £33,000 to £56,000 by MyJobQuote, and a 20 to 30 m² single-storey extension at £44,000 to £60,000 by the same source. But they give you different things: a loft gives you bedrooms, while an extension usually gives you a bigger kitchen and living space.

What does the 'original' house mean?

Permitted development limits are measured against the original house, so earlier extensions count against you. Even one built by a previous owner does.

Do I need to tell my neighbour?

If you apply for planning permission, the council has its own process for telling neighbours. Under permitted development nobody has to. It's still sensible to talk to them, especially if the work is on or near a shared boundary.

Does a conservatory count?

A conservatory is an enlargement for planning purposes. Its building warrant position can differ from a solid extension. Ask your council's building standards team.