Start with one shared scope
Give every bidder the same current drawings, finish schedule, equipment list, site information and written scope. Record any addenda and make sure all bidders price the same revision.
If the design is incomplete, ask bidders to identify what they assumed rather than silently filling gaps differently.
Normalize the money
Create a comparison sheet for each trade and major scope item. Distinguish fixed-price work, allowances, unit prices, alternates, owner-supplied items, taxes, bonds, insurance, permits and exclusions.
Do not add an allowance to one bid and compare it against another bid that excludes the same work. Ask for clarification in writing before deciding.
Compare schedule and responsibility
Ask for a realistic schedule with procurement, submittals, permit review, inspections, long-lead items and owner decisions shown as dependencies. A promised completion date is only useful when the assumptions behind it are clear.
Clarify who coordinates each trade, who submits permit documents, who manages inspections, and how changes are priced and approved.
Check the evidence
Verify the contractor's license and insurance through appropriate official sources, confirm relevant project experience, and contact references for work of a similar size and use. Keep a record of what was checked and when.
Treat a verbal assurance as an open item until it appears in the proposal or contract. Ask a qualified construction professional and attorney to review terms that affect risk or payment.
Choose the best-supported plan
The strongest bid is not automatically the cheapest or the most detailed. It is the proposal whose scope, assumptions, schedule, exclusions and responsible parties you can understand and verify—and whose gaps you can afford to resolve.