Elimination of musty earthy smells drawn into house?


Old 11-07-18, 03:37 PM
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Join Date: Aug 2016
Location: us
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Elimination of musty earthy smells drawn into house?

Several of the closets on the first floor of our two story house draw an unpleasant earthy smell from under the house which sits on pylons so there is mostly just earth under the house. It seems like the house is acting like a chimney and is at lower pressure than the outside.
Background: The house was built in 1975 and when built had no heating or furnace or duct work (it doesn't get too cold here in CA). It had a flat tar and stone roof with no attic. Twenty years later, a roof was put on and a furnace was installed inside the attic. Since the house was already built, they put enclosed chases for the hot air on the outside of the house. They couldn't cut into the floor so the heat comes out of the floor on the first floor but the ceiling upstairs. The return air to the furnace is underneath furnace on the 2nd floor ceiling.
I tried sealing the closet floors and walls and sealing around the doors but to no avail. Sometimes the problem is worse than other times and I'm not sure if it is temperature or wind related. When it is the worst, the smell even comes up into the walls and would come out the electrical receptacle box if you took off the faceplate.
At first I thought if I put a vent to the outside from the closet wall then the inside and outside would be at the same pressure - or would that just provide more lift in the chimney. How to stop the smell?

Any advice would be much appreciated and thanks in advance!
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Old 11-07-18, 04:32 PM
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Location: NC, USA
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I think you are incorrect assuming that your closets are drawing air up from below. Small, enclosed spaced with no airflow are a perfect home for mold and mildew which might be creating the smell you associate with air from below.
Old 11-08-18, 09:35 AM
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Join Date: Aug 2016
Location: us
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Thanks for the reply. If you crack the door to the closets slightly, or feel underneath the door, you can feel the air come out. The fact that the air flows out led me to believe that the house was under lower pressure than the outside. Behind the granite on the kitchen sink there is a small 1/4" gap between the wall and the granite that communicates with the space inside the wall. Sometimes you can feel air flowing from this and it smells earthy/musty too.
Old 11-09-18, 08:48 AM
airman.1994's Avatar
Join Date: Dec 2005
Location: VA
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cover and seal the ground under the house with 6 mil poly.

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