FEMA staff must use the Appendix L checklist for large permanent work estimates. First they confirm a licensed engineer, architect or certified cost estimator prepared and certified it, that it uses unit costs rather than lump sums, and that it is detailed enough to match the scope. Then they check that every item is required by the agreed damage, removing or returning anything ineligible.
A signed estimate from a licensed professional engineer, licensed architect or certified professional cost estimator, with a certification that it follows industry standards and corresponds to the agreed damage; unit costs for each scope component; and the agreed damage description and dimensions.
Ask your estimator to build the estimate to the Appendix L checklist from the start. An estimate that fails step 1 never gets to the reasonableness review and simply comes back.