Thread: Air duct interface with slab

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If they have ducts in the slab, that bit of missing sealant around that duct is the least of their worry.

Originally Posted by Clay White

I fairly sure there are metal ducts in the slab.

Then this is worth repeating:

Originally Posted by Rick Hurst

If they have ducts in the slab, that bit of missing sealant around that duct is the least of their worry.

Rust, water infiltration, mold, musty, nasty, rodents, etc.
Other than that, they are just fine and are still allowed with certain restrictions if you are not in a flood prone area.

Ducting in the slab is required to be completely encased. I cannot recall for sure, but I think it is a minimum of 2". However, they are often not encased and the bottom of the duct, in contact with soil, will rust out. In addition, as the duct is below grade, and concrete will often crack, the ducting could very well ship water into it.

Since this is a visual inspection, defer to an HVAC contractor.

Ducts in the slab is just one of the contributors to the downfall use of Chlordane. Many termite control persons have actually drilled into the slab and accidentally pumped chemical into these ducts. Cleanup costs were outrageous and led to lawsuits.

I personally know of (1) case here in the DFW area.

If you like the musty smell, thats a reason to consider them I guess.

rick