Stone foundations & French drains
I've worked on many old houses, but need some advice on this problem. I'm currently renovation an 1810 cape in western Maine. Structurally, the house is in good shape considering its age, but there is a real water problem in the cellar. The walls are comprised of the usual split rock and some field stone, and they still straight and solid. It is a full cellar with approx 7' walls. Some time ago, a concrete floor was added with a French drain around the perimeter and a sump pump at the low side. The problem is the amount of water coming in from the outside - especially on the front of the house that faces toward a slight hill. When the pump was off last year (when the house was up for sale), the water rose to almost 3' deep. Even when the pump is running, moisture is a constant issue. The problem is compounded by the rain water shedding off the metal roof.
My question: Can I put a French drain of sorts on the outside of the house to divert the water away from the structure without damaging the integrity of the foundation? Or is there a better way to address this problem?
Many thanks in advance for your thoughts on this issue.