How should I compare quotations with different exclusions?
Normalise them. List every exclusion, assumption and provisional item across all quotes, then add an estimated cost for each item a quote leaves out, so that each total covers the same scope. Use identical provisional sums in each quote where possible. The lowest normalised total, not the lowest headline price, is the fair comparison.
From the RRD Field Guide, checked against the sources cited in Variation Orders and Provisional Sums: How to Stop Surprise VOs on Singapore Building Works. General information, not advice for your project.
The fuller picture
Surprise variation orders usually come from scope that was never fully defined, items excluded from the quote, provisional sums used as placeholders, and concealed site conditions. Owners reduce them by defining scope in drawings and an itemised schedule, pricing exclusions when comparing quotes, requiring written instructions and quotations before varied work starts, and agreeing valuation rules in the contract.
More questions on this topic
- What is a variation order?
- What is the difference between a provisional sum and a prime cost sum?
- Is a lump-sum quotation fixed no matter what?
- Can a contractor claim for variations done on verbal instructions?
- How are variations valued?
- What are dayworks?
- Who bears the cost of concealed conditions found during A&A works?