Crawl Space Vapor Barrier


  #1  
Old 08-05-04, 07:56 AM
teman99
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Question Crawl Space Vapor Barrier

Recently purchased a home in Penn and since the warm weather hit have a strong mildew smell inside. Crawl space has open dirt floor with thin fiber board (insulation) attached to ceiling / floor joist. my question should i put down a vapor barrier on dirt floor? Seems to be alot of pros and cons from people (draps moisture?) Please help
Thanks
Tom
 
  #2  
Old 08-05-04, 06:00 PM
C
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I would look for a source of the mildew smell inside.
 
  #3  
Old 08-06-04, 04:10 AM
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Vapor Barrier

You need a 6 mil layer of plastic sheeting over the dirt floor.

This is a large source of water vapor enetering your basement or crawlspace and a cause of condensation which will lead to mold and mildew growth.

Building code in Pennsylvania requires 6 mil plastic over a dirt basement or crawlspace floor.
 

Last edited by homebild; 08-06-04 at 04:11 AM. Reason: Kerry for President
  #4  
Old 08-07-04, 01:04 PM
teman99
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Thanks Homebild for info. My question then is: If i put craft R19 insulation inbetween joists and vapor barrier on floor does this somehow drap moisture down in crawl space? Seems to be a couple of schools of thinking on this.
Tom



Chris,
I've been looking for the source of the mildew smell and have found zero leaks inside the home and in attic. The place had been closed for at least 6-8 months with no heat and old 1960's aluminum windows which are not sealed
(replacing them next week), That's why I began to investigate the crawl space thinking this could be the cause. Not sure where the problem is and am not a happy homeowner.
Tom
 
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Old 08-08-04, 07:45 PM
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My thought would be that the plastic will keep the moisture out of the crawlspace and the vapor barrier will keep the moisture out of the house. But what seems to be a better approach is to put down plastic on the soil and insulate the crawlspace walls and the sill beam.
 
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Old 08-08-04, 08:51 PM
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Only 1 School of thought

"Seems to be a couple of schools of thinking on this."

Nope.
Not at all.


Only 1 school of thought in Pennsylvania and that is the State's UCC (Uniform Construction Code) which mandates a 6 mil polyethylene sheet over a dirt crawlspace floor and insulation on the walls and floor of the crawlspace.

No other opinions need apply.

Whatever other information you may be getting that seems to contradict what I have stated is not Pennsylvania Building Code and does not apply for our state.
 

Last edited by homebild; 08-08-04 at 08:53 PM. Reason: Kerry For President
  #7  
Old 08-12-04, 05:49 AM
teman99
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Homebild
They had put up this 1/4" cheap so-called insulation covering MOST of the ceiling/ joists of the crawlspace using ferring strips.It's in poor shape (holes, failing down in a few spots). I want to put the barrier in asap, but have to wait till fall to do the insulation on walls ($$$ is why).
Should I rip this down before puting the vapor barrier on the floor? I don't undrestand how, but some believe that having both covered... ground and ceiling will cause moisture to get trapped.
Also with all this rain, If the inside of crawlspace is totally dry (which it should be) should i wait until the ground around the outside of the crawlspace has dried some?
What about the windows (3) and vents in crawlspace open or closed?
I know it may sound like a dumb question, but the only dumb questions are those not asked.


Thanks for all your help guys!!!!!
 

Last edited by teman99; 08-12-04 at 06:04 AM.
  #8  
Old 08-12-04, 07:05 PM
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Barriers

teman99:

I don't think your dumb and glad you have asked.

First order of business is to remove the 1/4" foam from the underside of the floor joists. It is a waste of time and is doing nothing positive to helpt your situation.

Where to add vapor barriers and vapor retarders is not an easy question to resolve and neither is when to keep foundations vents open if at all.

But according to the Pennsylvania Uniform Building Code, a single ply of 6 mil plastic sheeting should be installed over the dirt floor. The reason is to prevent ground moisture and ground vapor from entering the crawlspace or basement from below.

This 6 mil layer should be sealed at all seams.

But Code also requires that insulation be placed in the ceiling of crawlspaces and recommends this insulation be fiberglass with the jraft paper facing going UP against the heated living space above. Code for most basement crawls around the state means you need to put at least an R-30 in the floor joists above the crawlspace but your county may require more so consult your local building code office. (or if you tell us what County you are in Pennsylania I'll tell you what the Code requires of you).

Whether or not you keep your vents open at all depends upon whether the crawlspace is a 'conditioned space' or is open to a 'conditioned space'.

A 'conditioned space' is defined as any area that is purposely heated or cooled or residually heated or cooled.

What this means in simple English is that if your crawlspace has any heating or air conditioning equipment within it, or is open to a basement that has any heating or air conditioning equipment within it, the vents hsoul remain CLOSED at all times particularly when the dirt floor is covered with at least 1 layer of 6 mil plastic.

Long story made short:

Cover the floor with 6 mil plastic.
Close the vents.
Insulate the crawlspace walls.

That's Pa Code.

Any questions contact me at homebild@praize.com because I don't always read here...
 

Last edited by homebild; 08-12-04 at 07:08 PM. Reason: Kerry for President
  #9  
Old 08-17-04, 08:41 PM
teman99
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HomeBild
Thanks for your thorough answers. Not easy to get the straight answer on this one from most. Ps. I'm in Pike county
Thanks
Tom
 
 

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