How to perform stellar DD?

[Michael Albaum]

Hi all,

I recently closed on a 8-plex building, 2-story, brick construction back in August. I'm an out of state investor and thus was unable to physically get out to the building myself, but had a trusted professional building inspector perform an inspection. I just got word from my PM that one of the tenants in the lower units (partially below grade) complains that when it rains, water seeps into his walls. My PM tells me we may need to dig a few feet down to try and repair the leak after the next rain and we've been able to positively ID the general leak location.

My question is, other than interviewing folks during DD, what is the best way to determine issues that are only present during certain environmental conditions (i.e. high winds or strong rain)? Also, if the unit is vacant during inspection and DD, there may not be anyone to interview. Any and all thoughts are appreciated.