Compare equivalent proposals
A lower price may omit electrical work, making good or follow-up testing. Ask each contractor to set out the proposed method and explain why it suits the measured level and floor construction. Compare like-for-like scopes before choosing.
Separate the one-off and ongoing costs
Equipment and installation are only part of the total. Fan systems use electricity and may need maintenance or replacement parts. Ask for the fan specification and use your own electricity tariff to estimate running costs.
Ask what happens after installation
Confirm who arranges the retest and who pays. Ask how the contractor handles a result that is still elevated and whether further work is included or separately quoted. A written process is more useful than a general promise of success.
Be careful with online price tables
Check when the underlying prices were collected and what they include. Historical public guidance can illustrate relative costs, but it cannot replace a current quote for your property. Save the quote date, VAT status and exclusions with the proposal.
Sources & further reading
UKHSA: reducing radon levels and historical costs ↗General guidance for property owners. Check the original source and obtain advice specific to your building.