Photos and video of the damage before any cleanup begins are the most important documentation, insurers generally want to see the extent of the damage as it occurred, so capturing this before items are moved or cleanup starts protects your position significantly.
Keep any invoices or receipts related to the cleanup itself, professional flood cleaning, equipment hire, or emergency repairs, as these are typically claimable and insurers will want an itemised record rather than a lump sum estimate after the fact.
A written report from the cleaning or restoration company detailing the extent of water damage and work performed adds further support to a claim, and is worth requesting as standard practice whenever professional flood cleanup is carried out on an insured property.
