Holes in baseboard heating = foundation water drainage?

[Jeremy Bartlett]

The past couple of weeks have been... educational... I am a new landlord, just purchased and occupy a 4plex. Tenants in one of my units were gone for a week and came back to standing water in two of their bedrooms. We got the water shut off, home warranty company called, plumbers deployed, and water mitigation company put to work. Home insurance company was put to work, and contractors were lined up to do the repairs. Long story short, copper piping replaced with 40 feet of pex piping, two feet of drywall/insulation removed from 3 out of 4 walls in two bedrooms (where we discovered more nails that were put into section of piping from when previous owners installed trim during a reno), and things have been progressing.

The water mitigation company has now expressed concerns that moisture may be seeping into the wood strut wall foundation from the outside (their numbers of saturation went up during a rain storm). I ran a hose under a window on the wall where numbers went up for an hour and they are coming back tonight to take another reading. If they come back with confirmation that water can hit the walls from the outside - what should I do? Is it as simple as putting asphalt sealer along the base of that wall and calling it a day? Or are we talking digging out a trench around the perimeter of the property to spray foam and dig French drains? Things have escalated from a simple leak to a huge project and I'm starting to feel like we are in pretty deep...

Any insight is appreciated.