Wayne,
I marked areas of damaged wood with "X" or areas of leaks. I write on notes on the wooden joists of where termite activity found. Then I take a picture and place it on my report. It assures the client also that I actually crawled under the home.
Another quirk I do is I alway write the date and my name, company name on a floor joist near the crawlspace entry and in the furtherest corners of the crawl so I have a reference if there is ever question how far I went.
If I can't go past a point in the crawl, I note it also.
I've went back on some homes that I inspected numerous years ago, and have still found my chalk writing still there. Kind of like the Egyptians I guess.
