Exposed soil under bathtubs in slab house

I came across a slab-on-grade foundation house built in 1984 that had exposed ground soil underneath each bathtub, as viewed from the access panels in the room behind each. Has anyone else run into this?

The groundwater had caused some damage to the framing members around the tub, and some termite damage was evident. Why would this be setup this way? And what should be done to fix the moisture issues being caused? Would you recommend they put down a 6-mil poly vapor barrier like in a crawl space? Or should concrete be poured? This is in the middle of the house with absolutely no ventilation getting to it.

I am not sure why they would do it this way but I do know that it should not be like that. Recommend a contractor evaluate and repair it. In this case I would not recommend the actual repair. Write what you see and get the experts in to sort out the mess!!

Did you probe the soil to feel concrete? Normally there is a hole in the slab for the tub drain. This hole size can vary, 8 x 8 to 12 x 12.

Gophers will find there way to the spot and start filling the void around the tub with soil. Sometimes there’s very little soil and sometimes it can be full. The earth to wood contact in turn in invites subterranean termites an rot.

Soil needs to be removed, damaged framing replaced and the hole gets treated for termites. To prevent this from happening again, I recommend pouring a thin slush coat of concrete in the hole to prevent the gophers from coming back up but is still easy to break out if needed for future plumbing repairs.

Hope this helps.

Thanks so much, Greg & Mike!