How do we remove moisture from duct/cement slab foundation 1 yr after flooding? We own lower level of a 4 unit town home.

Asked by Joanne and John Stacey
Palatine, IL

We own a lower level unit built on a cement slab with a shared walls of the common area foyer. In 07/11, the upstairs unit's hot water tank broke, flooding our utility room walls/celing and common area. A restoration company removed/replaced the affected dry wall/flooring/carpeting and dried the opened wall of our unit with huge fans but did not lift our furnace/AC unit and dry our unit's cement/slab foundation. As of 08/12, we have professional meter readings of 70% + humidity throughout our home and toxic air. resulting in documented medical issues. Two weeks ago a duct/vent agent found mud in our ventsducts that are below the cement flooring in utility room. Our HVAC company verified our AC/furnace is functioning w/o problems. (Also,in 07/11, the townhome assoc used a small house fan for 2 weeks to dry the foyer but refused remove/treat affected soggy carpeting and shared walls). 


Two items within your question raise questions for me. The first is the presence of mud in the ductwork below the slab and the second is the use of fans by the restoration company. 

Mud in the ductwork

First the duct below the slab. If there was mud found in the ductwork below the slab this points to the a problem with the way the ductwork joints were seal and whether or not the proper vapor barrier was installed below the slab. This is a serious problem.

  • Having mud and water present allows for the growth of mold and mildew which is a potential contributing factor to your health problems which you had stated.
  • I would have the complete system scoped with a camera to document the extent of contaminates entering the system.
  • Also cord drilling through the slab will allow you to assess whether there is a vapor barrier installed.

The repair for this if the problem is determined as improper sealing of the ductwork would require the entire slab to be removed to access the ductwork to remove and replace the entire duct system.

Drying out the room

The second item of the use of fans to dry out the room. This is not a proper technique.

  • The restoration company should have installed large dehumidification systems to remove all traces of moisture from saturated material including framing.
  • I would recommend using a humidifcation probe to check the levels in the studs and concrete.

You might consider consulting with an enviromental hygienist to perform the tests and document the finding.

I wish you much luck and success in your endeavors to rectifying this situation.


For more information:

Read "My heating ducts are installed in the concrete slab of my house. I get water and dampness in them at times. Is there a way to stop it?" a Q&A answered by Andy Ault.

Tagged In: ductwork

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