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My house has a stone foundation but the inside walls of the basement have been covered with concrete. The basement is currently dry but I just removed 4″ concrete that was on the outside of the house between the house and thr driveway and intended to minimize water penetration. Now that I removed the concrete so I can landscape that strip of dirt should I dig along the foundation and waterproof? If so, should I apply a layer of concrete? Shoudl I pour a couple of inches (2″-4″) of concrete up against the foundation? Should I tar? If I should do any of these things to what depth? Note: I removed the concrete only last weekend and have had only one heavy rain and didn’t notice any water in the basement.
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Hi Tom,
I don't know your location so I don't know if you are subjected to freeze thaw cycles.
Generally, you don't put concrete onto stone foundations. The concrete will cause the stones to crack.
You should patch any damaged joint mortar and clean the surface and then apply a good dampproofing, backfill with sand or protect the dampproofing during backfilling.
Gabe
*Gabe, thanks for the reply. I've been talking to some other folks about what they had done. My neighbor excavated down to the footing, plastered the wall up to the surface with cement (1/4"-3/8" coat), applied roofing tar to the plaster, put a perforated PVC drain pipe at the bottom on top of some crushed stone, ran the pipe into his house through the foundation wall and into a sump pump, covered the pipe with more crushed stone, then filled the trench back up. He did this 30 years ago and hasn't had water come since then. Do you have any reservations about that kind of approach?
*Hi Tom,No reservations as long as you parge the outside face over a clean surface to make sure that you get good adhesion.Gabe
*Gabe, thanks for the reply. I've been talking to some other folks about what they had done. My neighbor excavated down to the footing, plastered the wall up to the surface with cement (1/4"-3/8" coat), applied roofing tar to the plaster, put a perforated PVC drain pipe at the bottom on top of some crushed stone, ran the pipe into his house through the foundation wall and into a sump pump, covered the pipe with more crushed stone, then filled the trench back up. He did this 30 years ago and hasn't had water come since then. Do you have any reservations about that kind of approach?
*when backfilling grade away from the house foundation at an angle for 3' and lay black plastic 6mil the length of the house. Lay #15 felt over it to keep the plastic from puncturing and level it off with the rest of the backfill. This underground grade will move the water away from the foundation.
*Gabe,I have dug down to the footing of the foundation. It appears to be loose stone that only goes down as deep as the bottom of the basement floor. I would like to dig down approximately 6-8" below that level to lay a couple of inches of crushed stone and a perforated PVC pipe to use as drainage that would come back into my basement and into a sump pump. Would going down a few inches past the bottom of the footing destabilize it?
*Hi Tom,No, going down a few inches shouldn't undermine the foundation wall.I wold imagine that you are founded on some type of hard pan or stone. Those old timers normally started their stone foundations on solid material when your house was built.Gabe
*Gabe,When I run my perforated PIC drainage pipe into my house I will probably be running under the foundation wall. Is there anything I should be concerned about when digging underneath the stone wall? Should I reinforce anything?Thanks,Tom
*Morning Tom,You only need a minimal tunnel (the width of a shovel) under your foundation so there shouldn't be any problem. If you wanted to open an area a couple of feet wide, you would have to start thinking about stones becoming dislodged.You have to think in terms of a pyramid. Any loading at the top of the foundation is spread out in the form of a pyramid, widening and spreading the load.Gabe
*Hi Gabe,I have another question you might be able to answer. At the bottom of my trenches I was thinking of using sheets of 6 mil plastic or 15# felt to ride along the bottom 6-12" of the foundation-coated wall down to where the perforated PVC pipe lays to make sure any moisture sliding down the wall would be moved in the direction of the pipe which will be below the bottom of the wall approximately 6-12" away from the wall and approximately 4" below it. Does this sound like a reasonable approach to you? Would the plastic chemically react with the foundation coating (I used Monsey Premier Foundation Coating)?Thanks in advance for your thoughts.Tom
*Hi Tom,I wouldn't spend any money on felt or plastic if you've done a good job with the foundation coating and you extended it down to the bottom of your wall and over the footing.(you wouldn't know if the water was going over or under the plastic)The drainage pipe should be in and covered with clean crushed stone. A filter cloth can be applied over top to prevent any silt from clogging the pipe.If you were to be concerned with the exterior foundation coating being scrapped during backfilling, you could protect the coating with a sheating of asphalt impregnated board. (but only if you have a lot of stone in your fill.)Backfill with sand or gravel and remember to slope away from your house.Gabe