Building Regulations Cost & Fees Guide 2026
Building Regulations approval is required for every extension, loft conversion, and structural alteration — even if you do not need planning permission. This guide explains the costs involved.
Cost breakdown
Building control fees
Building control fees are paid to either the local authority or an approved inspector. They cover plan checking and site inspections. Typical fees: £400–£600 for a standard extension, £500–£800 for a loft conversion, £600–£1,000 for a two-storey extension.
Technical drawings cost
Building Regulations drawings (technical construction details) are separate from planning drawings. They show foundation details, insulation specifications, drainage connections, and structural sections. We price these after your survey; costs from an architect or technologist vary depending on the project.
| Item | Cost |
|---|---|
| Building control fees (extension) | £400–£600 |
| Building control fees (loft) | £500–£800 |
| Building Regs drawings (PlanBuild) | Priced after the survey |
| Building Regs drawings (architect) | £500–£1,500 |
| Structural calculations | Priced after the survey |
| Total (PlanBuild route) | Council/building control fees plus our fees, quoted after the survey |
Prices based on Dorset rates, 2026
Frequently asked questions
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