This fall I bought a house in Providence, RI, built around 1930. The house is on about a 7% grade, which steepens more in front of the house down to the street.
The previous owners “partially finished” the basement, which involved putting some kind of laminate flooring directly on the concrete: 
During heavy rain, we noticed water collecting near the uphill wall, and after ripping out some rotting drywall found a 0.5” x 1.5” hole bored all the way through the foundation (I could poke dirt on the other side). Fortunately the uphill wall is almost entirely still exposed, the hole happened to be in a place where an interior wall met the foundation wall.
Humidity is generally pretty low (around 40%, though that’s only been in fall and winter).
I plugged the hole with hydraulic cement (filling the whole cavity). Since then we haven’t had a heavy rain storm.
We’d like to more properly finish the basement and make sure the basement stays dry, and are considering an interior perimeter drain. We’re considering:
- Do nothing and hope that plugging the hole fixed the issue long-term
- Put a perimeter drain only along the uphill wall
- Put a full perimeter drain around the whole basement.
One thing that worries me is that the flooring is a bit warped throughout most of the basement, and after ripping some of it up there seems to be mold underneath. I’m not sure if that’s from more water ingress or just moisture coming up through the concrete.
What’s the best way to make sure this basement stays dry?
