Water in Air vents on a slab SFR house.

[Oliver Santiago]

Hi Everyone,

Has anybody had experienced water filling up on a n air vent on a slab, no basement or crawlspace SFR home? My tenant called me and reported that there was water present in the air vents located in the bathroom, kitchen and in one of the bedroom. If anyone has had this problem, I would appreciate your feedback. Any recommendations as to what to do and who to hire to find out the problem will be appreciated. Thanks in advance

[Tom W.]

@Oliver Santiago

In slab, HVAC duct systems are fairly rare but they do exist. I have only had experience with one that filled with water over the last 40 or so years that I have been in the business. Unfortunately, the fix is not easy or cheap. Outside of the chance that someone filled the duct system, either intentionally or by mistake, with water, the only explanation is a high ground water table that has allowed the water to leak in. If it has done this once, it will continue to do it every time the ground becomes saturated. This being the case it means you now have a very real possibility of mold growth in the duct system.

The only real fix, that I know of, is to abandon the under slab duct system. The vents would need to be sealed with concrete to prevent water and mold infiltration into the house. A new HVAC duct system could possibly be installed overhead in the attic if the house allows that possibility. If not other alternative means would need to be considered.