Include the inspection report, any repair addendum or price adjustment, the contractor's signed agreement and payment schedule, invoices and proof of payment, permit applications, and the revised capital schedule. Pair each cost with the document showing it was incurred by the enterprise rather than estimated.
Tie every revised number to a source document
A spreadsheet that no longer matches the contracts invites questions. Reconcile the original budget, the change orders, and the current bank records, then explain the difference in a short narrative. Where a figure is still an estimate, say so and identify the quote behind it.
Missing items can usually be supplemented later, so an incomplete file is a reason to keep collecting rather than to abandon the plan. Attach a name to every document you intend to file: who issued it, and what were they in a position to know. An inspector's report is evidence of observed condition, not of who pays.
A contractor's signed agreement evidences a commitment, and the payment record evidences that it was honoured. A permit application shows what an authority has been asked for, which is a different fact from what it has granted. Assembling the package this way exposes the items where you hold nothing but your own assertion, and those are the ones for which to obtain third-party evidence.
Hypothetical example: an investor's revised schedule lists a drainage remediation, and the file carries the contractor's signed scope and the paid invoice rather than a note explaining the increase.