How to compare building tenders when prices and exclusions differ

To compare building tenders, establish whether each contractor has priced the same design, scope, responsibilities and programme. Keep the submitted prices visible, then record the differences, seek written clarification and show any adjustments separately. The lowest headline price is only useful once you understand what it includes.

For a bespoke home, differences can sit in the detail: who develops a specialist design, whether an item is a firm price or an allowance, what access has been assumed, and which finishes or external works have been excluded.

By Friel Welch · 16 October 2026

Confirm the information each contractor used

Start with a schedule of the drawings, specification, scope and pricing documents issued for tender. Check revisions and later clarifications. If one contractor has priced an earlier design or assumed a different specification, the figures are not yet comparable.

Record discrepancies before attempting to rank the offers. Ask for clarification against the same information and keep a record of the response. An unexplained adjustment in a comparison spreadsheet does not change the contractor's offer.

Read the exclusions alongside the price

Prepare a list of excluded work and unclear responsibilities. On a private home, useful checks include demolition and enabling works, temporary works, utilities, external works, kitchens, joinery, specialist lighting, controls and commissioning.

Where an item will be bought directly by the client, establish who will coordinate, receive, store, install, connect and protect it. A client-supplied fitting can still create work for several trades. Record those interfaces so that the same cost is neither omitted nor counted twice.

Separate confirmed prices from allowances

Identify provisional sums, quantities awaiting confirmation and other allowances. Ask what each allowance covers, what information is missing and how the final amount will be established.

A lower allowance does not necessarily represent a saving. If two bidders have allowed different amounts for an unresolved package, compare the basis as well as the number. Keep the uncertainty visible until the scope and price have been agreed.

A simple example: why the ranking can change

Illustrative example only; these are not Friel Welch project figures. Assume two offers cover the same work except for one joinery package, with all figures excluding VAT:

• Contractor A submits £1,000,000 but excludes the package.
• Contractor B submits £1,080,000 and includes the defined package.
• Contractor A subsequently confirms £100,000 to include that same package and its associated work.

On that clarified basis, A's comparable figure becomes £1,100,000 and B's remains £1,080,000. The initial £80,000 difference has reversed: B is now £20,000 lower. This calculation only holds if the remaining scope, assumptions and terms are equivalent.

If the £100,000 were your adviser's estimate rather than A's confirmed price, it should be labelled as an estimate. It would help assess exposure, but it would not be a contractor commitment.

Compare programme and delivery assumptions

Check proposed start dates, duration, working arrangements and the information needed before work can begin. Understand assumptions about access, storage, occupation, client decisions and specialist lead times.

For example, a proposal based on uninterrupted access to an empty property is different from one allowing for phased work around an occupied home. Establish whether both contractors have allowed for the same conditions before treating the price difference as a commercial advantage.

Keep qualifications and proposed alternatives visible

Separate a contractor's compliant offer from any alternative material, design or method proposed to reduce cost. Ask the design team to assess the effect on appearance, performance, coordination and maintenance before a substitution is accepted.

Commercial qualifications should be reviewed with the relevant advisers. Record the agreed position in the final documents, rather than relying on an assumption that a clarification email will resolve every inconsistency.

What should the tender report explain?

A useful report shows the original offers, confirmed clarifications, comparison adjustments and remaining uncertainties. It explains why the recommended contractor is appropriate for the project, taking account of relevant experience, the proposed team, programme and the agreed scope as well as price.

The recommendation should identify any matters that must be resolved before appointment. If work is still undefined, the client needs to understand the potential exposure and the decision required, rather than seeing a single apparently settled total.

Project example: Russell's Water, Oxfordshire

At Russell's Water, a private residence of approximately 8,000 sq ft, Friel Welch's appointment included review of Stage 4 architectural, structural and building-services information, preparation of scope and pricing documents, contractor clarifications, tender analysis and procurement recommendations.

That work connected technical review with the commercial comparison. Following contractor selection, we supported contract preparation and pre-construction mobilisation. The case study sets out the scope of our involvement.

Get a clear view before committing

Friel Welch provides quantity surveying and tender analysis for private clients, working with their architect and wider team to understand contractor proposals. Contact us to discuss your tender returns.

For the wider budget, read how to control construction costs without compromising the design. For assessing the people who will carry out the work, see choosing a contractor for a country house renovation.