Estiquote

Local costs · Wales · September 2026

How much does an extension cost in Conwy?

A mid-range 25 m² single-storey extension in Conwy costs about £56,500 to £70,000 including VAT, or £2,300 to £2,800 per m² at Welsh prices. Conwy charges £648 for building control on a 10 to 40 m² extension (full plans, including VAT): the 5th cheapest of the 91 councils we checked, 23% below the typical council (£840). With design, a structural engineer, building control and a 15% contingency, budget £71,000 to £92,000.

By Estiquote · Prices reviewed · Council fees from Conwy's published schedule · How we calculate

Work out your project in Conwy

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Typical prices in Conwy

Mid-range finish, Wales prices, including VAT. The budget adds design and engineering fees, Conwy's building control charge and a 15% contingency.
ProjectBuilding workBudget to plan for
Single-storey extension, 25 m²£56,500 to £70,000£71,000 to £92,000
Double-storey extension, 40 m²£82,000 to £104,000£101,000 to £133,000
Dormer loft conversion, 30 m²£51,000 to £62,500£63,500 to £81,500
Kitchen, medium£8,600 to £15,200£9,800 to £17,500
Bathroom refit£5,600 to £8,500£6,500 to £9,700

Building prices in Wales run about 10% below the UK average outside London. Kitchens and bathrooms vary less from place to place than extensions and lofts.

Building control fees in Conwy

Conwy council charges including VAT (plan and inspection combined)
WorkCharge
Extension up to 10 m² (full plans)£466
Extension 10 to 40 m² (full plans)£648
Larger extension, 40-60 m² (full plans)£715
Extension 10 to 40 m² (building notice)£648
Loft conversion up to 40 m²£648
Garage conversionNot published

Conwy charges £648 for building control on a 10 to 40 m² extension (full plans, including VAT): the 5th cheapest of the 91 councils we checked, 23% below the typical council (£840). Source: Conwy's building control charges, 2026-27. Published net ("VAT to be added at standard rate"); inc-VAT computed here at 20%.

Private approved inspectors set their own prices and are often competitive, so it is worth asking one or two for a quote as well. See how Conwy compares with every council we checked.

Notes on Conwy's schedule

Own schedule (in 2026-27 application form). No garage-conversion line. Loft up to 50 m2.

Planning

In Wales, householder planning fees are set by the Welsh Government. Check the current fee on Planning Portal before you apply.

Other councils in Wales

Building control for a 10 to 40 m² extension:

Questions people ask

How much does an extension cost in Conwy?

A mid-range 25 m² single-storey extension in Conwy costs about £56,500 to £70,000 including VAT for the building work, or £2,300 to £2,800 per m², based on Wales prices reviewed in September 2026. With fees and a 15% contingency, budget £71,000 to £92,000.

How much is building control in Conwy?

Conwy charges £648 (including VAT) for a 10 to 40 m² extension (full plans), according to its published schedule (2026-27).

How much does a loft conversion cost in Conwy?

A mid-range 30 m² dormer loft conversion in Conwy costs about £51,000 to £62,500 including VAT for the building work, and about £63,500 to £81,500 with fees and a 15% contingency.

Before you get quotes