Collecting three bids and choosing the cheapest works for commodity services. Construction is not a commodity service. The range of quality between the highest and lowest bid on a Bay Area renovation is rarely reflected in the price comparison alone.
Why Bids Are Not Comparable
Unless proposals specify identical materials, scope, and permit approach, they are not comparable. “Flooring installation” is not the same specification as “Karndean LooseLay LVP, 6 mm wear layer, floated over 1/4-inch lauan underlayment with all seams taped.” The first invites any product. The second is a specification.
Hidden Scope Differences
Contractor A includes permit fees. Contractor B does not. Contractor A prices in proper shower waterproofing membrane. Contractor B plans to rely on modified thinset. These differences do not appear in line items — they appear in project outcomes three years later.
How to Force Comparability
Provide a written scope document to every contractor you invite to bid. Ask for unit prices on major components. Ask what is included for permits, debris disposal, and protection of adjacent areas. Ask how unexpected conditions are handled and priced.