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What does a quantity surveyor do on a house build?

A quantity surveyor prepares cost plans, measures the works, prepares or checks tender documents, compares tenders on a like-for-like basis, values work in progress for stage payments and prices variations as the job proceeds.

On a one-off house, the most valuable QS input is early: a realistic cost plan against the sketch design, before the design is fixed and before you commit to a site or a mortgage figure.

During construction, an independent valuation of work in place protects you from paying ahead of progress and gives your lender the certification they need for stage drawdowns.

Where a QS earns their fee

  • Cost plan at design stage before commitments are made
  • Tender documents that allow genuine comparison
  • Interim valuations for stage payments
  • Pricing variations before they are instructed
  • Final account agreement at completion

Sources

Last reviewed 28 August 2026. General information only — not legal or planning advice.

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