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I’m buying an old brick/brownstone (circa 1899) mid-block 4-story townhouse. The place was completely gutted in the 1980s, including excavating out about 2/3 of the basement – down an extra foot or two and pouring an 18″ concrete “retaining” wall along the perimeter along with the new concrete floor.

My inspector called this little retaining wall by a nickname — a ‘knee’-something. He said that it wasn’t the best way to underpin, but that it was very common, and that it can be perfectly fine. However, there’s no way to tell if it was done properly, and he can’t guarantee that the foundation wasn’t compromised. A couple days later, over the phone, he told me that since the underpinning was done twenty years ago, any problems would have surfaced by now and that there’s nothing to worry about. (He was also impressed by the quality of the plumbing and electrical work, so he said it was a solid building.)

I went to the DOB and pulled all the records anyway. Everything looks like it was done right – permits and plans filed and approved for plumbing, mechanical ventilation, etc., over a few years – except there was no specific “underpinning” work described anywhere.

What do you think? Is this kind of underpinning common? Your experience would be greatly appreciated. Thanks!