I have an older house (circa 1919) that was built without a basement (just a crawl space). About 1965 a basement was added.
Along one of the old concrete foundation walls there is a 7 foot section that has nothing under the bottom of the wall! (See image below.) In the last 10 years 2 pieces of the wall have cracked off the bottom . The pieces weigh maybe 150 lbs and 50 lbs. This concrete wall is only about 2 feet in height (the bottom is maybe 20 inches below ground level).
It seems to me that this wall is at risk of falling in completely. I realize I could call in a professional to fix it ($$$). But would like to at least consider any options I may have to fix this myself. I am an avid do-it-yourselfer and in 25 years have only ever hired a contracter one time (to replace my steep roof).
Anyone have any good ideas about how to fix this problem? Extra points if your suggestion is work I could do myself. 🙂
Thanks!
EDIT: My diagram may give the wrong impression about one point: the old foundation wall is unsupported for a 7 foot section only. But somehow it is still hanging in place. The rest of the wall does have dirt under it holding up.
Best Answer
This is probably just a good comment but I would highly suspect that the old wall is providing zero support. Just because things are connected to it does not mean that it is supporting those things.
Given that a new basement was poured there is a 99% chance that they pushed those walls up to provide load support to the entire house. Since this was done in 1965 I am pretty sure I am correct or you would have a warped/bent floor on the edges.
The concrete that is malfunctioning on you is simply concrete breaking down because it is holding up itself. Concrete is really bad at this. That is why structures like parking garages require tons of rebar and meshing even though they are mainly concrete. And even then concrete will crack and fall. I am guessing yours has nothing internal supporting it.
My recommendation would be to fill in the void as well as possible with drainage rock and aggregate. There are techniques you can use when adding the rock to pressurize the load for that small wall better. But note that the load is only itself.
The other note I would make is the most concerning part of your picture is the angle of the missing dirt. It seems that the void clearance runs into your usable foundation. I would add enough dirt to add a size ramp to offset any wicking water to the other direction (8-12 inches higher).