Start with one common information pack
Send each contractor the same version of the drawings, the same description of the intended work and the same available surveys. Identify documents by date or revision so that an updated layout is not confused with an earlier proposal. Include photographs of access and existing conditions if they help explain the site. When a contractor asks a question that changes the scope, share the resulting clarification with everyone preparing an offer. Otherwise, the difference between quotations may reflect unequal information rather than a difference in price or approach. Keep a simple register of the information issued and the assumptions agreed.
Read the work descriptions and measurements
A quotation line should explain what is being measured and what operation is included. Excavation, loading, transport and disposal may be separate items, even though they form part of the same visible activity. Similarly, a paving price may include only the finished surface or may also include excavation, sub-base and drainage. Check the unit and quantity alongside the description. A square metre of one specification is not equivalent to a square metre of another. Ask about significant differences in quantities rather than assuming the lower number is automatically more efficient. Measurements should be traceable to the agreed design or an explicitly stated estimate.
Make a comparison table of inclusions
List the main packages down one side of a table and the quotations across the top. For each package, record whether it is included, excluded, provisional or not explained. Add a separate row for site setup, access arrangements, temporary protection, waste handling, tests and final cleaning where these are relevant. The table does not need to be complicated; its purpose is to reveal gaps. Avoid replacing an unexplained omission with your own guess. Ask for clarification and update the comparison before deciding. Some services may be supplied by the owner or another contractor, but that division must be deliberate and coordinated.
Understand allowances and possible changes
Existing buildings and groundworks can contain conditions that are not fully visible before work starts. A quotation may therefore include assumptions or provisional quantities. These are not necessarily a problem, provided their meaning is clear. Ask what evidence would trigger a review, how the change would be measured and who needs to authorise it. A provisional allowance should not be mistaken for a guaranteed total. Equally, a fixed total should be read together with its exclusions and the documents on which it relies. The important question is how uncertainty is handled, not whether the document uses reassuring language.
Review the programme and the practical arrangements
A start date and a completion date do not explain the whole programme. Ask about the sequence, the information needed before commencement and the dependencies on suppliers or other trades. If a home, business or access road remains in use, clarify how the work area will be separated and which interruptions may be needed. Payment stages should correspond to the agreed contract and identifiable progress. Review the treatment of taxes and any fees that sit outside the construction scope. These details make the offer understandable as an operational proposal, rather than simply a number at the bottom of a page.
Prepare a focused follow-up conversation
Before choosing, write down the three or four differences that most affect your project. They might concern drainage, a material specification, an uncertain quantity or the timing of a critical delivery. Ask each contractor to address those points against the same documents. For a project in Girona, ECOSTA can review an enquiry with the location, the intended works and the information available. The aim is to reach a clearly defined proposal that you and your technical team can assess. A careful comparison at this stage can prevent a much harder discussion about missing work after construction has already begun.
A simple final check
Before making your decision, ask whether someone unfamiliar with the earlier conversations could understand the agreed scope from the written proposal. If an important inclusion exists only in a verbal explanation, have it recorded. Check that any clarified assumptions have been incorporated into the latest version and that you are comparing those latest versions. This final review is especially useful when offers have been revised several times. Keep the comparison table with the documents on which the decision was based.