Vapor Barrier

[Roger]

I am collecting alot of moisture on top of my plastic vapor barrier and underneath the floor of my house. It is a new 3200 sq. ft. home with block foundation and I have 22 automatic vents around the foundation. There is no water going under the home. We have had alot of rain the past three weeks. May be a circulation problem. Should I remove the Vapor Barrier?

[Eugene]

When you say vapor barrier, i am hoping that you mean the ground vapor barrier.
The black materail on the bottom of the floor is a bottom board, not a vapor barrier.
If the water is inside the bottom board, check your AC condensate line to make sure it drains outside the home. Or look for a plumbing leak.
If it is on top the ground vapor barrier, again check the ac line and make sure the site is graded away from the home.

[Roger]

Eugene, Thanks for your response. The moisture is on top of the 6 mil black plastic that is on the ground, if there is a low spot it puddles. In some areas it collects above, on the black material that secures the insulation. There are not any leaks, the AC condensate is drained to the outside of the foundation. This condition covers most of the crawl space. MY thoughts, the plastic on the ground is trapping the moisture from all the humidity we have had the past three weeks. I'm thinking of putting exhaust fans in the foundation or remove the plastic that was laid for a vapor barrier, or both. Anyone ever had this problem?

[David Oxhandler]

Rodger -

It really depends on where you are and what is under that plastic. I an in Central Florida where the ground is mostly sand. We would never consider a ground barrier as the ground is so absorbent here that the underside of most mfd homes is always dry and dusty. What is the soil like where you are. If the plastic was removed would the ground absorb the moisture? With some soil conditions the ground is so wet that it is necessary to maintaining a ground barrier.

You say you have " 22 automatic vents around the foundation" what is automated about them ? Is the home on a foundation with a solid concrete perimeter wall or is the "foundation" skirting that hides the view of the underside of the home? How big are the vents? The underside of your home needs adequate venation. If you don't have a certain percentage of the skirting vented you are guaranteed to have condensation problems.

Get out the local yellow pages and phone several MH installation (set-up) contractors and ask them what is customary and recommended in your location, for ground barriers and if your automatic skirting ventilation is adequate.

[Karen]

I would suggest several things..........

First off, you need 1 square foot of venting under the home for every 150 square foot of floor in the home. That does not mean just measure the space the holes in the skirting take up but the actual open area of the holes multiplied by the number of holes. They also have to be within a specific distance from the corners. I assume by automatic you mean that's all they are, holes. There is usually no mechanical ventilation under a home.

Secondly, moisture is getting under the home somehow. You did not say you had gutters and downspouts, if you don't put them on and redirect the rainwater AWAY from your home. Dryer vents, leaking lines, air conditioner condensate, etc. NOTHING is to drain under a home.

Is your driveway draining AWAY from under the home or towards it? The same for your sidewalks or any patios? Is the highest point of your lot the center line of your home underneath? If not, someone did not prepare your lot properly. Usually where the skirting is is a low spot. You could use a perimeter drain around your home if you have someplace to drain it to such as a storm drain or a swale or ditch off lot. CHeck the lay of the park. When it rains does the park drain through your lot? If so, ask the operator to install drainage to take the water off site onto the street where hopefully there are storm drains.

Look around. Moisture is the death of the home.