Hi everyone,

Before starting the work on waterproofing my rubble foundation I wanted to validate some questions with the community, especially those who have experience with foundation extending outside building.

Building Description:

– 2-story building with a rubble/stone foundation from ~1900.

– 1-story brick house added on top ~1950.

– 2nd story in wood added ~2000.

Basement Details:

–  Basement covers ½ of the building, 6 ft below grade, with a poured concrete floor.

– 4/5 of the walls are reinforced with concrete and/or brick; the rest of the foundation is 3’5” below grade.

Foundation is reinforced with poured concrete and steel rods from the exterior, sitting on white sand.

Climate Zone: 5a

Heating System: Located in the basement, which is quite warm.

Moisture Issue: Observed on basement walls/ground starting in springtime.

Questions:

1. Cutting Holes in Dimple Mat: I was advised to cut holes in the dimple mat where it horizontally covers the rubble foundation to allow vapor to escape and dry out the soil. I am concerned that this might let rainwater soak through the holes, but I understand it will eventually dry out upwards. Do you agree with this advice, or do you have alternative suggestions?

2. Insulation: I was advised against putting insulation directly on the rubble foundation to allow it to dry out, and even against placing it outside the dimple mat. In my situation, exterior insulation will have an insignificant effect since the foundation extends out of the building. Has anyone explored insulating options in similar circumstances?

3.  Perimeter drain pipe depth: My dry well allows for a perimeter drain pipe depth of about 3.6 feet, which seems adequate. However, in the part, where the basement is located (1/2 of building), the pipe will run in the middle. Will this still function properly? I have a sump pump inside the basement, and I could install a drainage pipe at the 6.5-foot level, running it through or below the rubble foundation to the sump pit. However, I am concerned about potentially damaging the rubble foundation and have heard mixed reviews about bringing water from exterior to sump pumps. Does the benefit outweigh the risk?

Any other suggestions are welcome! Many thanks in advance!