Return air ducting through slab?

Looked at a house yesterday built about 1950, single story, that ‘looked’ like a concrete foundation.
One return air duct was located in entry hall near center of house, but in examination, the ducting traveled down appx. 2’ below floor level and turned toward end of house where furnace was located. Looked into attic thinking they traveled the duct up in wall cavity, but did not find any evidence in attic.

Has anyone seen a full slab foundation with return-air ducting through slab, travel under slab, then through slab again to unit? :roll:


Quite common here in 1950’s homes.

As a matter of fact, I ran into one of those setups again today, with plumbing in the slab, too. When I mentioned it to the buyer, she got very nervous. “What if the plumbing needs repaired or replaced, will they have to break through the slab?” she asked. I explained that a plumber could evaluate to see what the best repair method would be, and that it may or may not require breaking through the slab. I can understand her concern.

Under slab ducts can be a problem with moisture condensation, rust, mold, radon and other things. May require a closer look and replacement may be warranted.

Good idea to defer what you can’t see.

look at this, the home owner tried to fix damage and sale, the water was not on the disclosure.:smiley: :smiley: