Yeah, they can be a real pain to find. But using the Spring Cleaning mod, once you find them and scrap them, the hammering open air stops. The don't stop as soon as the house is deleted, you do have to hunt them down. Just wait for someone to start hammering then look in the exact area and eventually you'll see it pop up with "Hammer Animation" then just R to scrap and Enter to confirm and it's gone. It is literally just empty air that it appears you're scrapping, but it works so it doesn't bother me. I found and deleted two of them... now my people just crouch down and sit there where the hammering spot used to be. At least the incessant hammering has stopped, but it would be great if someone could mod it out.
