QuestionsCategory: QuestionsHVAC ducts with water under basement floor
Handyman Staff asked 11 months ago

My wife and I are under contract to purchase a home built in 1999.

During the inspection last week, we noticed this odd hole in the basement floor, next to the water heater. It was partially covered with scraps of 1" lumber, with more scraps next to it:

Furnace opening

Looking in the hole, our inspector found several old towels and standing water:

Water in duct Water and towels

Following up on what this could be, I was able to speak to a previous owner, who told me this is where (15+ years ago) there used to be a separate furnace which serviced the basement. While they owned the home they had water in the ductwork. The furnace was removed and new ducting installed in the basement ceiling, serviced by the other furnace.

I assume the towels were put in the ducts in an attempt to block drafts, which fell out once soaked with water.

The current homeowners tell us (of course) that they've never had any problems with water in the ducts in the 9 years they've lived there. In fact, the reason their disclosure had not mentioned any issues with known standing water was because they had forgotten about it completely.

In two of the basement bedrooms, the vent openings in the floor were filled with cement before LVP flooring was installed. In the other bedroom and the family room, the vent holes are still there and can be felt under the carpet, I assume waiting for a bed frame or dresser leg to discover and tear through.

It has been an unusually wet Spring, but the amount of and level of the rust next to the 8"-12" diameter ducts tells me this is not a one-time event.

Two days ago, I had another inspection visit with a contractor for his opinion. We discovered the homeowners had removed the towels, debris and water, but there was 1-2" of new, clean water in the hole. It had rained the night before, so perhaps this tells me something of how quickly/easily the hole gains new water.

How serious should this be considered? My thoughts include potential flooding, of course, but also the potential for mold or structural problems with the slab itself if the ducts were to fail. What else should I worry about?

What options would we have to remediate the problem?

  • Put the slats back over the hole and hope for the best?
  • Fill the ducts with gravel or concrete and forget about it?
  • Install a sump pump in (or below) the hole?
  • Cut through the slab, remove the ducts completely and repair?
  • Run far, far away and look for a different house?

What remedy would you accept, in my situation?