Plan for solving basement moisture problem
We're in the process of remodeling the basement of our 120 year old house. The basement slab is about 4 feet below grade. We don't get much water, just an occasional damp spot on the slab after really heavy rain. But the stone foundation walls do show some efflorescence and some mold, especially below grade.
I know that the only surefire way to eliminate moisture in the basement is to install a french drain system around the perimeter of the house, thus preventing any ground water from getting to it. Due to cost and other factors, this is not a step I'm eager to take right now. However, I am going to be re-landscaping in the spring, and am working out a plan to create an 8 - 10' band of relatively dry ground around the perimeter of the foundation.
Here's what I'm thinking:
Currently there are roofed porches that extend about 8' beyond the foundation off the front and back of the house. I'm also planning to install a concrete or asphalt driveway along one side of the house, which will seal against the foundation. So three sides of the house will be done.
A yard area is on the fourth side of the house. Here I plan to slope the grade away from the house and extend the gutter downspouts out into the yard. In addition, I'm thinking of installing an 8' to 10' wide planter area along the whole length of this side of the house, fed by a drip irrigation system and covered w/a waterproof membrane sealed against the house. This would not prevent all water from getting through. But if done well should transfer 80% or more of surface water out away from house.
I'm wondering how far this approach seems likely to go toward resolving our basement moisture problem? Are there additional steps I could take (short of installing french drains) that I should consider?