Flooded HVAC ducts

ductsfloodingfoundation

I own a house (Built in 1966) on a shallow hillside, around which recent rain has caused complete ground saturation. On my bottom floor, which is on a concrete slab, the three floor vents were recently filled entirely with clear water. We paid a contractor to remove over 700 gallons because I did not own a pump. Yesterday the same thing happened, so this time I purchased my own pump and removed about 500 gallons. Overnight they filled back up, so it seems the water has moved enough soil to find its way in much faster.

So now I am researching ways to stop this from happening altogether, instead of reactive repairs. I have found two possibles:

  • Digging a curtain trench uphill of the house to stop groundwater from penetrating the foundations. Then digging french drains downhill to allow groundwater to flow away from the house faster.

  • Using a product, such as Airseal, to completely seal up the vents.

The first I can probably do myself for under $1,500. The second seems to cost around $2,500 for my size house (2,200 Sq.Ft.).

So I'm looking for advice on where to start. Am I overlooking something? I did purchase some masonry waterproofer to apply around the edges of the house, but have yet to apply it. Is that worth doing?

Best Answer

Instead of patch repair solutions for the ductwork in the foundation, have you considered looking into quotes to add new ductwork along the ceiling of your walkout basement by branching off the ductwork under the house on top of the hill. You could then add ceiling vents that should never have water issues.

In the short term, this could be a costlier option, but in the long term I think it could be the cheaper option because:

  • A "patch" solution for the existing ductwork seems prone to failure again at some point in the future which will cost more money to repair incrementally.
  • You will waste less money on heating/cooling the ground year-round by having the ductwork inside the conditioned space.