Is it okay to place plywood over a dirt floor if it is placed on pressure treated wood off the floor and the dirt floor covered with plastic?
Right now natural wood gets moldy under there. Will that plywood also accummulate mold and make other problems?
The room is not underground but it is still very damp in there.
Covering the dirt with plastic will help, but not solve the moisture problem. The moisture will still penetrate.
It would be helpful if you could make holes along the perimeter of the structure, if possible, for ventilation which would allow some of the moisture to escape.
Cover the holes with screen to prevent rodents/animals from moving in.
All wood will be mold over time, even though you putting a vapor down, and you cover the or leave it open it doesn`t get to dry out properly and moisture stays trap somewhere between the ground and the wood.
Take for instance wood decks they get moldy when not properly maintain, or they are shady areas.
Without seeing your floor it's hard to tell what your dealing with, but it sounds like your on a crawlspace foundation. I am also assuming you want to install hardwood flooring with a plywood base to nail or glue too.
The "old" school of thought on crawlspaces was to vent them so you can open up the space and let air flow through in the summer and close the vents off in the winter.
Were vents installed in your foundation? If not it's ok as the "new" school of thought is to not vent the crawlspace area but to install plastic for a vapor barrier on the ground and insulate the underside of the flooring and ALL walls in the crawlspace, so you will need enough space to do so between the ground and the treated wood.
I would highly recommend a dehumidifier as well, installed by a licensed plumber and make sure they put the drains outside of the crawlspace. This would take out all the moisture in the air and protect your flooring above. I would also go as far as adding another vapor barrier under your wood flooring in the house, tar paper etc. If you take these steps you should be fine.
Good luck with your project.
Just to add a small amount of additional moisture insulation, try a layer of styrofoam below the plastic. It is close cell foam and will add to the moisture barrier of the plastic. Has worked for me on projects i have done before.
Do not place the plywood directly on the soil. This WILL cause it to mold.
"AVOID encapsulating your crawl space with Visqueen plastic or any cheap replicas -even if it is a 20 mil thickness or higher. This is because plastic starts to break down and will become brittle in a few years, especially if moisture is present. The correct way to encapsulate a crawl space is by using a polyethylene based product."
The article below might help you out a lot.
You need to put down a moisture barrier. Some astm tar paper between the dirt and plywood likeon the hoist or use some roofing emulsion by treating the the plywood facing the dirt.
The object is to keep the wood dry and protecting its natural oils.... Moisture darkness are the molds best habitat.
Put a 4 mill vapor lock over dirt floor, use pressure treated nailers for plywood, use preasure treated plywood 3/4" fasten with galvanized nails or screws....In my opinion...Pour concrete.
You can use a thick plastic to cover dirt then place 2 inches of stone to provide a sturdy base and some drainage.
it is important to use pressure treated materials which can also be sealed with any clear or even color based sealers. It also important to check the exterior base of wall and to assure that any contact with ground with be water tight. this solution is not for high traffic area, its more for storage floors although sturdy and safe to walk on some creeking may accur unless stone is compacted.
I want help how to get service for the particular category
A heat source is the best way to control moisture. It could be as simple as a string of lights.
Search the TrustedPros directory and discover the best contractors in your area.Find your home service pro