How Much Does a House Extension Cost in Glasgow? (2026 Guide)
If you're thinking about extending your home in Glasgow, the first question is always the same: how much is it going to cost?
The honest answer is it depends — on size, specification, site conditions and what you're building. But we can give you realistic ballpark figures based on what we see day-to-day as a building contractor working across Glasgow and the Central Belt. If you’re looking for builder to carry out house extension, regardless of what stage your at get in touch.
Typical Extension Costs in Glasgow (2026)
Single-Storey Rear Extension
Shell only (no finishes): £2,000–£2,500 per m² +VAT
Mid-range (standard finishes): £2,500–£3,000 per m² +VAT
High spec (underfloor heating, bi-folds, high-end kitchen): £3,000–£4,000+ per m² +VAT
A typical 4m x 5m (20m²) single-storey rear extension in Glasgow would cost roughly:
Shell only: £48,000–£60,000 inc. VAT
Mid-range: £60,000–£72,000 inc. VAT
High spec: £72,000–£96,000+ inc. VAT
Double-Storey Extension
Generally 40-50% more than a single-storey of the same footprint (you're adding a first floor but the foundations and roof are already being built)
A 20m² footprint double-storey (40m² total) might cost £80,000–£130,000+ inc. VAT depending on spec
Wraparound Extension
Larger footprint, more external walls and potentially more complex roof details
Typically £90,000–£160,000+ inc. VAT depending on size and specification
Loft Conversion
Velux conversion (no dormer): £45,000–£65,000 inc. VAT
Dormer loft conversion: £60,000–£90,000 inc. VAT
What Affects the Price?
Size
The bigger the extension, the higher the cost — but the cost per m² often drops on larger builds because fixed costs (foundations, roof, scaffolding) are spread over a bigger area.
Specification
A basic plastered room with standard fittings costs far less than a kitchen extension with underfloor heating, bi-fold doors, quartz worktops and high-end appliances. The finishes make a bigger difference than most people expect — especially when investing in high-quality kitchen installations or bathroom renovations.
Site Conditions
Access: Can we get materials in easily, or are we carrying everything through the house?
Ground conditions: Some areas of Glasgow need deeper foundations or piling due to old mine workings or clay
Drainage: Moving or connecting to existing drains adds cost
Party walls: If you're building near a boundary, you may need a party wall agreement
Planning & Building Warrant
Most extensions in Glasgow need a building warrant from Glasgow City Council (or East Dunbartonshire Council if you're in Kirkintilloch, Bishopbriggs, Bearsden or Milngavie). Some also need planning permission. Budget £2,000–£4,000 for architectural drawings and fees.
VAT
Most building work is subject to 20% VAT. Make sure any quote you receive is clear on whether VAT is included.
How to Get an Accurate Quote
The only way to get a reliable figure is to have a contractor visit your property, understand what you want, and price it based on the actual scope of work. Be wary of anyone who gives you a fixed price over the phone without seeing the site.
At MKS Construction, we provide detailed, itemised quotations so you can see exactly where your money goes. Our director is a qualified Quantity Surveyor — cost management is what we do.
Looking for trusted house extension builders in Glasgow? Our experienced team can guide you from design to completion.
If your project involves more than just an extension — perhaps a full property renovation or a new build— we handle those too. For commercial or insurance work, see our commercial construction page. And if you want professional cost management without appointing a main contractor, we offer standalone QS and project management services.
Ready to Get a Quote?
Contact MKS Construction for a free, no-obligation site visit and quotation. Call 0141 459 1659 or email info@mksconstruction.co.uk.
We build extensions across Glasgow, Kirkintilloch, Bishopbriggs, Bearsden, Milngavie, East Kilbride and the wider Central Belt.