How it works
A unit cost bundles the material, labor, and equipment for one unit of a task: one square foot of drywall installed, one linear foot of baseboard, one roofing square. Multiply the unit price by the measured quantity and you get the line total. This is the backbone of Xactimate and of how Florida carriers scope and price claims. It makes an estimate auditable, because anyone can re-check the measurement and the published unit price.
Unit cost vs. lump sum
A contractor's lump-sum bid, such as kitchen repair for 22,000 dollars, gives the carrier nothing it can verify, so carriers routinely discount it. A unit-cost estimate exposes each assumption, which is why it holds up in negotiation and in appraisal. The tradeoff is that if a quantity is measured wrong or a task is left out, the error hides inside otherwise reasonable line items.
Where it matters in Florida
Because Florida carriers price in unit costs drawn from regional price lists, matching that method removes the your-number-is-unsupported objection. Confirm the quantities against the actual measured loss, and confirm the unit prices reflect current, local, reasonable and customary rates.