How Much Does Building Control Cost for an Extension?

In England and Wales, the council's building control fee for a single-storey extension of 10 to 40 m² is £499.20 to £1,584 depending on where you live, with a median of £858, including VAT. Every council there sets its own charges; Scotland and Northern Ireland work differently (see below). We read the fee schedules of 216 councils on their own websites; the table is below, and every figure links to the page it came from.

What the fee pays for

Building regulations approval is separate from planning permission. The council's building control team checks your plans and then inspects the work as it goes up: the foundations, the drains, the structure, insulation and fire safety. Most councils split the fee into a plan charge, paid when you apply, and an inspection charge, paid once work starts; the figures here add the two together and include VAT.

Your builder or architect usually makes the application for you, so the fee often appears as a line on their quote. The fee covers the council's checks only. It does not cover drawings, a structural engineer's calculations or the build itself, and many councils charge extra if electrical work is not done by an electrician registered with a competent person scheme.

What each council charges

Fees for a single-storey extension of 10 to 40 m² and a loft conversion without a dormer, from each council's own schedule. Councils band the work differently, so we used the band that covers a 25 m² extension and a 35 m² loft.

The cheapest and the most expensive

Cheapest: Chorley (£499.20), Flintshire (£499.20), South Ribble (£499.20), Newark and Sherwood (£504), Rushcliffe (£504).

Most expensive: Islington (£1,584), Tower Hamlets (£1,551.60), Greenwich (£1,514.40), Lewisham (£1,500), Southwark (£1,472.75). The same extension costs 3.2 times as much to approve with one council in England and Wales as with another.

A loft conversion without a dormer costs £428 to £1,782 to approve across the same councils.

57 councils price each job instead: 51 quote each job; 3 charge by the hour (Ipswich £104.40, Shropshire £130, Tonbridge and Malling £68); 3 price by the cost of the work (Westminster, Camden, City of London). Type your town in the box above to see how yours prices it, and ask for a quote before you apply.

For 35 councils we could not confirm a current fee: the council publishes none, or its schedule is a draft or does not say whether VAT is included. Their building control teams will quote on request.

Private building control

You do not have to use the council. Registered building control approvers, private firms registered with the Building Safety Regulator, can approve the same work instead, and they quote job by job. It can be worth asking one for a price to compare with the council's.

Scotland and Northern Ireland

In Scotland, building work needs a building warrant from your council's building standards service. The fee is set nationally by the estimated value of the work, not by each council, and it rose by an average of 8% on 1 April 2026. The Scottish Government's free online fee calculator gives the fee for your project. Scottish Government.

In Belfast, a single-storey extension of 20 to 40 m² costs £243 to approve (a plan fee plus an inspection fee), and a roof space conversion £291.60. Belfast City Council.

Get your extension quoted

Building control is a small part of the bill: the build itself is where the money goes, and what builders charge varies more from town to town than the council's fee does. Compare a few quotes, and check whether each one includes the building control fee.