Costing
Comparing contractors’ offers: the same basis, or nothing
Comparing two offers is not comparing two totals. It means checking that they describe the same thing, at the same level of detail.
Start with a common basis
For offers to be comparable, contractors must price the same specification: same items, same quantities, same standards. Without this basis, each one interprets the project in its own way, and the lowest offer may simply be the most incomplete.
The points to check line by line
- Items and quantities: is everything provided for priced, and in the same way?
- Assumptions and exclusions: what does the contractor assume, and what has it left out?
- Options proposed: are they priced separately, with their impact?
- VAT: amounts excluding tax or including all taxes, for all offers.
- Deadlines, payment terms and guarantees.
- Unit prices, which will later be used to value variations.
Explain the differences, not just note them
A gap between two offers always has a cause: an exclusion, a different assumption, a forgotten item, a different level of finish. As long as the gap is unexplained, the comparison has not been made.
Deciding with full knowledge of the facts
Once the offers have been brought to the same basis, the choice becomes simple again and you make it with full knowledge of the facts. It is the client (project owner) who decides which contractors to proceed with; the expert assessment serves to provide comparable information, not to decide in the client’s place.
Key takeawayAn offer is only comparable once it has been brought to the same basis as the others: same items, same assumptions, same terms.
Sources
The information is summarised as at the date of publication. Always check the text or scale currently in force before deciding.