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Moisture problem in garage conversion

Zim123 | Posted in General Questions on

My wife and I live in a converted air-tight 750sqft garage in Sacramento, CA.  There is no thermal break between the slab (w/stem walls) and flooring- only a vapor barrier.  The layout is an L shape with the living room/ kitchen in alignment with the bedroom and the bathroom/ laundry room off the side of the bedroom.  Ceilings are vaulted with no attic space.  The HVAC system is two mini split units back to back on the wall separating the family room and bedroom.  In the winter – we run the bath fan and open windows during and after showering but have moisture condensing around the floor perimeter as well as windows, etc.

Will a stand-alone dehumidifier in the bathroom do the job- or are we a good fit for an HRV or ERV-type system?   I have no experience with either.

Someone asked about moisture levels, but we’ve been out of town.
I got a cheap hygrometer – at 2:00 it reads 65% relative humidity and 74 degrees inside, while 30% humidity and 65 degrees outside.  I’m not sure how to measure the slab temperature, but the average temperature in the two cold months is in the mid 40’s.  

I’m guessing a small dehumidifier isn’t going to do the job.

Thanks again

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Replies

  1. Expert Member
    DCcontrarian | | #1

    If condensation is happening, the surface is cooler than the dew point of the air that touches it. But we need to know more. Do you have a way of measuring indoor temperature, outdoor temperature, indoor humidity, outdoor humidity? And also the temperature of the slab?

    1. Zim123 | | #2

      Hello there- my apologies, I posted to the general pop again without seeing your reply at the bottom. Anyways, I got a cheap hygrometer – at 2:00 it reads 65% relative humidity and 74 degrees inside, while 30% humidity and 65 degrees outside. I’m not sure how to measure the slab temperature, but the average temperature in the two cold months is in the mid 40’s.

      I’m guessing a small dehumidifier isn’t going to do the job. Any advice is greatly appreciated.

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