The form of waterproofing back in the day (when these were built) was Kraft paper or building paper, with a limited life span. Not helpful when most of the homes we work on were built almost 100 years ago. You can see the thin building paper with the stucco exposed behind it. Our current waterproofing on horizontal surfaces is a bituthene membrane, much thicker with a substantial lifespan. New stucco has a double layer of paper and wire.
You can see that the foundation at the front side of the stairs and landing is only a few inches above grade and is crumbling, leading to settlement. When foundations are this close to the ground level there is often damage to the mud sill and framing at the base of the wall due to saturation from the ground.
More damage to the sheathing where the central landing meets the upper stairs. Note the 4”x4” beam supporting this interior corner. This should be a more substantial beam, and it is out of level indicating movement.
