RogerT, 9/28/2011,7:59:45 PM, wrote:

"badgolferman" wrote in message
...
RogerT wrote:

"badgolferman" wrote in message
...
It seems there is condensation building up underneath my house
on the end near the garage that doesn't have foundation vents.
Some of the joists have mold or a fungus on them. .....

I recently went to a meeting where an inspector talked about this
condition. He suggested no insulation between the joists or, if
there is insulation, to make sure it is unfaced insulation. ....

My house is in SE Virginia near the Chesapeake Bay. We do not have
basements in this area due to the high water table. The humidity is
high in this area. I have a moisture barrier on the ground and
insulation between the joists. The insulation has backing on the
side that touches the subfloor.

I think the problem may be that, in your high humidity area, and with
between-the-joists insulation that has any vapor barrier (even though
it is on the correct side), you are trapping the humidity in the
crawl space where it can cause moisture and mold on the floor joists.
And, since the outside air is humid, the fans don't change that. If
anything, the fans may be bringing in humid air from the outside and
just adding to the humidity (and condensation) in the crawl space.
You already have a vapor barrier on the floor, which is a good thing.
When someone described a situation similar to yours at the
meeting/presentation that I attended-- with faced insulation between
the floor joists -- the inspector's recommendation was to remove the
insulation altogether. Removing the insulation, in his opinion, will
enable any moisture in the crawl space to dry out. Keeping the
insulation (especially with the facing still in place) keeps the
moisture from being able to dry out.

This home inspector is also a licensed structural engineer (or
something like that -- I forget the exact engineering title/license
he has). Based on everything else he said at the meeting, and the
number of years of experience that he has, I was confident that he
knew what he was talking about on this crawlspace moisture issue.

I moved a fan from the porch area to the area that builds up
condensation and aimed it toward the other side of the house that is
dry and has a fan too. That fan blows toward the foundation that
has vents. The fans have been running straight for three days.
Hopefully it has dried out enough to remove the condensation by now.

I think I will call the company today and have them perform the
spraying that kills everything.

I think that the disadvantage of paying a company to spray now is
that it doesn't correct the underlying problem and the mold will come
back.

The company tells me what I need is a crawlspace dehumidifier. They
put down new moisture barrier, seal the vents, install a GFC line,
dehumidifier and pump all for $3000. That does not count spraying for
the wood destroying fungus. The dehumidifier is supposed to dry out
the area so much that all the mold will go dormant.