Define what the floor-area rate includes
Use the new internal floor area, then agree whether the rate covers a shell, a watertight structure or a finished room. A kitchen, bathrooms and complex glazing can distort a simple area comparison.
What belongs in the budget
Design fees, surveys, approvals, structural alterations, utilities, kitchen fit-out and temporary accommodation.
How the calculation works
Materials = area × material rate × (1 + waste percentage). Labour = area × labour rate. Add extras, apply the contingency to that subtotal, then apply the VAT rate. The result is a scenario based on your inputs, not a supplier quotation.
Compare the same scope
Send each contractor the same measurements and written description. Ask for a fixed inclusion list, exclusions, waste arrangements, payment milestones and the treatment of unexpected work. Do not compare only the headline total.
Common questions
Are these average UK prices?
No. Default rates are illustrative inputs so you can explore a budget. Replace them with current written quotations.
Does my location change the result?
No automatic regional uplift is applied. Local access, travel and supplier costs belong in the rates you enter.
Sources & methodology
- GOV.UK: building regulations approval
Planning permission and building regulations approval are distinct. Check the applicable nation and local authority.
Checked 8 Oct 2026