HELP! Mystery Moisture in Crawl Space


Old 08-04-10, 08:05 PM
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Exclamation HELP! Mystery Moisture in Crawl Space

I need some diagnostic assistance on finding the source of crawlspace moisture in my house. It is very sneaky.
The entire crawlspace is very dry except for a space underneath the front bathroom. The moisture is almost exclusively on the joist and sub floor. I check all the pipes under the house and have not found any leaks. All visible pipe entrances to the subfloor seem to be dry (by comparison to the surrounding areas). It honestly looks like the subfloor is sweating.
It is not a lot of water but there is substantial fungi growth in the immediate area.
I have had plumbers, environmental and crawlspace experts inspect the issue but still no answer. I am at a total loss. The total H20 involved is roughly 1/2 a cup of condensation but it is enough to spark impressive fungus growth.
Additional details: average crawlspace clearance - 24 inches / age of house - 100 years / crawlspace entry is exactly 8 ft due south of the problem area. / various vents in the crawlspace / Little Rock, AR / no leaks or moisture is evident in the bathroom above the infected area.


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Old 08-05-10, 06:09 PM
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what type of bathing unit is in that bath ? i would look for a leak in it. and/or water getting out of said bathing unit, onto floor and wicking its way down.

looks to me that you should be gutting that bath room.

post a pic of that room.
Old 08-05-10, 06:15 PM
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I have 2 theories. The first can be checked by touching the sub floor in various places between the joists. Use a thin plastic glove if you don't want to touch the mold. I bet that the dampest section is directly under the toilet. Either the wax seal is bad or the toilet has a hair line crack in it.

The second theory is the water is entering from an outside wall in a way that doesn't produce drips or an actual flow.
Old 08-05-10, 06:32 PM
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Do u have a vb on the floor? The crawl space vents should be closed in your area because u or in a green grass state.

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