Ranch style home with crawl space in SC along coast that is five years
old. This crawl space has 28% moisture readings in two or three areas
of the joists. The crawl space has approx. 2,179 s.f. with. The
design of house has two long earthen porches on the front and rear of
house without any ducting to allow venting to the crawl space. The
HVAC ducting is in attic, so this is not an issue. There are no
plumbing leaks in the crawl space. As such the house has no crawl
space vents on front, six on one end, four on opposite end and six on
the rear of house. A building inspector when we purchased the
property (three years ago) recognized this moisture problem and
recommended vapor barrier (plastic on ground) and two power vents.
Vapor barrier probably covers 75% of ground. I have installed a third
power vent and moved the power vents to one end of the house, closed
all the vents on the end with the power vent and opened all the vents
on the opposite end of the house. I was having a problem with high
moisture, mold build up on joists in the middle of the crawl space
against the walls where the porches are, so I modified the power vents
to pull air through the crawl space to avoid those "dead" areas along
the porch walls. The power vents move approximately 33,000 c.f. of
air per hour.
The question is should I cover the remainder of the crawl space with 6
mil platic and have the plastic go all the way to the walls and up
them for 6 to 12 inches to help alleviate the moisture problem?
Any other suggestions on how to alleviate this moisture problem!
The complete floor should be covered. It sounds like you may have poor
drainage and water is getting in. You say the mold is near a wall. Use
your moisture meter to locate the water when its raining, 28%
moisture in wood is caused by water leaking not humidity. Fix your
leaks and you wont need the fans,, Im sure you are spending 40 - 70 a
month to run them.
Yes, and overlap the new over the old. Don't go too light on the thickness either. The
overlapped area should be taped with a GOOD tape, not the type you get at a hardware
store, but that like #357 Nassau, that stuff will never come loose. Clean the plastic
the existing where the tape will be.
Run it up on the walls to secure it, or place clean stones in the corner of the floor
foundation to force the plastic to stable itself. I Have seen people tape or staple
sill plate, DON"T DO IT, it may cause problem. Also, don't run it all the way up, you
be able to inspect for termites and other problems. Maybe an adhesive that doesn't
plastic can be used, I'm thinking of the company that makes Liquid Nails, they have
of products for these kinds of project.
I once had a home so laden with moisture that the windows and doors were freezing
the winter time. Hot water heat, The homeowner did this very thing and we ended up
a humidifier in the home because it was so dry after wards.
The plastic covers 75 percent of the ground? That's like having a
roof that covers 75 percent of the house. Until you get all of the
crawl space covered with plastic, you are wasting your time. Yes,
cover with plasitic upto the walls and at least 1 foot up if the walls
are concrete. Otherwise it you seem to have a good handle on what to
do. Good luck.
See www.eren.doe.gov (Dept of Energy) and search for Technology Fact
Sheet titled Crawlspace Insulation. May identify it as number
DOE/G010099-774. This covers the subject in great detail.
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