First time here so hello everyone!
We have a house in Greece that is at least 100y old and its built from big (and small) stones with what looks like red sand in between the stones. The sand is very soft and can be rubbed away with the finger very easily. The roof is "new", maybe like 40 years and made from concrete and in good condition, so is the floor. We plan to make an extension to the house and that required excavations on one side of the house. It was made with a rock drill attached to a tractor… The excavation happened very close to the house and naturally removed some plastering from the lower part of the wall, exposing it to rain. And most likely the vibration and changes in support caused some cracks and movement of some stones on the corner of the house.
Now the plan is to fix the cracks, renew the plastering and perhaps most urgently to add some more support to the corner of the house, it looks like it might collapse with more rain and minor earthquakes that happen here occasionally.
What kind of support would you suggest and what kind of materials?
We have an engineer who suggest to drill stainless steel rods to the base rock and the big corner stones, glue them with epoxy and to make a some sort of concrete support to the corner… For the cracks he suggests lime based mortar in a quite liquid form to reach deep in the cracks… Any thoughts on this?
Im very conflicted the engineer, who is an experienced builder, but has very limited experience in this kind of renovation is insisting on using concrete to fix the corner. His logic is that to prevent the outward movement of stones, something very strong is needed. From what I read, natural stone buildings and old sand/claymortar (if its even mortar thats between the stones) don't go well together, but is it really a crucial issue in this case.
I have also been using ChatGPT's "Heritage Sage" gpt (attached), which at least to an untrained eye seems convincing. But as always in important matters it needs a human eye to verify the results. So any comment on this would be valuable.
Thank you in advance!
