A corner of my houses foundation sits on ledge rock. There's some corrosion that lets moisture in where the foundation meets the rock. The foundation is field stone and was built 100 years ago.

Why would someone build on ledge? And how can I repair the foundation? What materials do I use? Cement? I'm a new home owner and have lots of questions, sorry.

Thank you in advance.

  • 2
    Ledge is simply "bedrock near the surface" - there is no more stable foundation than that. Blasting it was expensive 100 years ago and now. Depending on the nature and orientation of your ledge, you may get some seepage through it which you really cannot do much about - if you have leakage between the foundation and the ledge, your best bet is to regrade the surface dirt on the outside of the foundation so that water runs away from the building.
    – Ecnerwal
    Nov 30 '15 at 23:05

Someone built on rock because the rock was where they wanted to put the house. This mighf reduce foundation cost, too.

You repair the foundation the same way you repair any brick or fieldstone foundation -- mortar in new pieces if necessary, tuckpoint to fill in eroded-away mortar, etc. Think of the ledge rock as a natural foundation slab and work from there.

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