Do photos and WhatsApp messages count as evidence?

Yes. Adjudicators and tribunals see phone photos and messaging threads in almost every dispute now, but three limits decide their worth. First, they must be capable of being dated and placed: a wide shot carrying the phone's date and location data proves the state of a named block on a named morning, where a close-up proves only that there was water somewhere once. Second, they must still exist when needed: photos live on personal phones that get replaced, and group chats vanish when someone leaves, so anything that matters must be exported into the project file while it can be. Third, they cut both ways: a thread showing the other side directing extra work also shows what your side said, promised and knew, and disclosure will not let you keep only the helpful half. Used well, a message captures an instruction nobody wrote up, in the instructing party's own words, and a photo routine on fixed positions builds a visual diary. But they are corroboration, not a system: they work best proving the entry the diary already made, not standing in for the diary never kept.

Take a mechanical subcontractor told, in a corridor, to get on with rerouting pipework around a clash. Nothing goes on paper, but the foreman messages the MC's engineer that afternoon: confirming you want the block C pipework rerouted per this morning's walk, starting tomorrow, and gets back a thumbs-up and the word yes. A year later the variation is denied: no instruction, no paperwork. The subcontractor produces the exported thread, date intact, with photos of the completed reroute from the fixed weekly walk. The message does what a confirmation of verbal instruction would have, in the other side's own words, and the variation is paid. It fails in the parallel world where the foreman changed phones in the spring and the thread went with it: the habit that saved the claim was not sending the message, but exporting it.