Mystery Moisture in Crawl Space NEED HELP

[porjohn]

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.

PHOTOS OF DAMAGE ARE ATTACHED.



ANY AND ALL ADVICE WOULD BE GREATLY APPRECIATED. THANK YOU IN ADVANCE.

 

[Chris]

What about the wax ring could it be leaking when you flush and getting into the floor.?

 

[porjohn]

Thank you Chris. I will check that and post the results.

 

[Chris]

To me it would be worth popping off the toilet and taking a look and while you are at it you get a new wax ring and bolts if you don't see any other problems that may be it.

 

[havasu]

As we all know, subfloors will not sweat without assistance from water. You have a few problems you will need to resolve before it gets real bad.

First order of business is to find the leak. In this situation, you may need to duplicate the flushing toilets, filling sinks, draining bathtubs, long showers, etc, with someone watching for leaks in the crawl space. Once the problem is found, fix it! Just remember, water will always flow down, and follow the path of least resistance. It may be something as simple as replacing the caulking in your tub or shower, or the wax ring under your toilet, or if you have had rain recently, could it be a leaking roof of gutter?

Your next order of business is to kill the fungi, which could be done with a solution of bleach. You will need proper ventilation for a week or so, to dry out any wetness. This could be accomplished by adding temporary fans into the crawl space, and removing any covers leading under the house.

Lastly, do not ignore this problem. It will only get worse and will not go away until you find the source of the problem.

Good luck and please let us know what you have found, in order to help others with similar situations!

 

[porjohn]

The problem was with the grout/caulk around the bathtub. There were a few gaps around the tub that were allowing water to slowly seep down into the sub floor.
The tub has been re-caulked and the fungi has been cleaned and dried. The staining on the wood is here for the long haul but the wood itself is still in good condition.
Thank you for the assitance.

 

[havasu]

I'm glad you found the problem. Thanks for the reply and helping others at the same time.

Also, for future reference, the next time your tub needs caulking, remove the old caulk, and then fill the tub about half way full of water before applying new caulking. This adds weight and opens the seams up, allowing you to really seal up the small cracks in it. Keep the water in the tub all night as the caulking dries completely.