Concrete question

[cmac2012]

I have a client with a house on a bit of a hill (built in 1925) which is experiencing some cracks in the stucco in various spots. Today I patched a large one at the bottom of the wall in this photo, up to and around the near side of the outcropping. Large as in one to two inches wide. Might be a chimeny above, not sure, below that is open space in the basement, so might not be a chimney, I don't remember the layout of the room on that floor, might not have been in that room ever.

Anyway, you can sort of see the little broomed pebble surface panels to the left of sidewalk sloping toward the house. In the corner where it meets the outcropping/chimney water collects, this I found when I hosed the stucco patch dust off the sidewalk.



Some of the wood bordering the concrete panels in the corner is spongy, no surprise, it has regular and long baths during the rainy season. They have water on the floor and walls below that spot in the basement during the rains. Not sure if any will continue to leak past the rotten wood. Doesn't seem good to allow a regular puddle at that spot.

My thought is to jackhammer those suckers out, remove the wood of course and pour some kind of new concrete with slope enough to keep water out of that corner. I've not done a lot of this, I'm wondering if I need to put one of those oily fiberboard things between the new concrete and the sidewalk. I gather that some movement can happen and a slightly flexible barrier is a good thing.

I used to see that stuff all the time in NM when I was a kid, seems like it's not used that much these days.

I know about using rebar pins to connect, what I don't get is if I should use the pins and the fiberboard, holes put in the latter to slide it over. Seems like an odd idea suddenly. I read once about some coating one could put on the existing concrete before pouring that could help with a mostly watertight joint.