Water follows the easiest path.
Sometimes the “easiest path” can be overcome by other forces–but usually water does run down hill.
“Wicking” is just such a force that can literally make water go up hill–or at least horizontal. We all know about sponges and their ability to “lift” water.
In the picture below, one can see a fungus growing out from behind the trim board at the exterior of the home.
Somehow water was getting into the wall structure–feeding the fungus. The culprit is that little white pipe at the top right hand corner of the picture. This pipe is the condensate drain from the high efficiency furnace. Because the pipe does not stick through the trim far enough, and because there is no elbow on the pipe, the condensate (water) does not drip off the end entirely and some of the water wraps around the bottom of the pipe and wicks back into the wall structure.
This is a condition that is conducive to wood decay rot, and an open invitation to wood destroying insects. Over time, decay within the wall will result–as is already indicated by the fungal growth at the exterior–and reinforced by mold growth on the drywall surface at the interior–drywall is a great sponge.
Extensive hidden damage would not be anticipated in this instance, given what we can see, but the wall will have to be opened up and all the damaged materials will need to be properly repaired and/or replaced as necessary–including replacement of the moldy drywall.
By Charles Buell, Real Estate Inspections in Seattle
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