Vapor barrier needed?

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  #1  
Old 01-08-06, 12:51 AM
kfc87
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Vapor barrier needed?

Hi All,

I live on the bottom floor of a condo. We're planning on putting laminate flooring in. The back of the condo faces a hill and during the rain season, water will pool up underneath the condo. In the summer there is no moisture under the floor at all. Should I install a vapor barrier even though there's no moisture in the summer?
The instructions said not to install a vapor barrier if it's not necessary.

Thanks
Victor
 
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  #2  
Old 01-08-06, 02:36 AM
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What is it your substrate- Plywood or concrete?

You should be conducting a moisture test.
 
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Old 01-08-06, 09:26 AM
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Not understanding why you would leave a floor unprotected from pooled water because its winter time. Of course you need a moisture barrier, and probably a lot more.
 
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Old 01-08-06, 10:32 AM
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For the small amount of extra $$$ I would use a vapour barrier. Now, be carefull, and use only products that state "vapour Barrier" on the label, do not use regular plastic poly, as it is not water proof. Overlap the seams by about 8 - 10", no need to tape, and carry it up the wall, where the baseboard will connect it to the wall. The vapour barrier should go on the slab, then the pad. I've inspected a lot of jobs that have it backwards
 
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Old 01-08-06, 06:14 PM
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Originally Posted by Rotty
Overlap the seams by about 8 - 10", no need to tape, and carry it up the wall, where the baseboard will connect it to the wall.
Yes, you need to seal the seam in the moisture barrier with a moisture proof tape, like clear poly packing tape.

But with that much moisture under the structure, it won't be long before the humidity levels entering the structure make the laminate swell and grow in dimensions.
 
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Old 01-08-06, 09:12 PM
kfc87
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Thanks for the replies. Sorry I wasn't too clear.

The subfloor is plywood. The water that pools up is underneath the subfloor about 3 feet below the subfloor under the condo. It's more like puddles from runoff. I can't do anything about it because it's the associations responsiblity. I just want to make sure the laminate I'm installing won't be affected by this pooled up water underneath the condo.

So the message I'm getting is even though the water pools up only in the winter, the vapor barrier is ok over a wood subfloor even though summertime it is very dry where I live. Is this correct?

Thanks again
 

Last edited by kfc87; 01-08-06 at 09:45 PM.
  #7  
Old 01-08-06, 11:27 PM
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The reason we don't recommend using a tape on the vapour barrier seams, is that most tapes contain plastics, as does the udercusions for laminates. We have seen in the past some problems associated with plasticizer migration which will swell the tape and cause some problems under the laminate, ie: level.

When you overlap the seams 8-10 inches, with the pressure of the pad and flooring on top of the vapour barrier seam, there is no moisture that will come through, with the exception of hydrostatic, which in that case you shouldn't lay the laminate on that subfloor.
 
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Old 01-10-06, 06:58 AM
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Clear packing tape is what all the manufacturers give you with their underlayment, if it doesn't have a peel and stick edge seal. Ever see clear packing tape on a 30 year old cardboard box used for storage? The stuff is still good and holding, but brittle.

The physics of plasticizer migration does not build mass/swelling. It is just transfering molcules from one surface to the other.

A moisture barrier is sealed. A moisture retarder is not. All plastics lose plasticizers over time and exposure. They then become brittle.

All it takes is for one wrinkle in a moisture barrier and minor but within tolerance variances in flatness of the substrate. I know your not overlapping 2-n-1, 10"!!!

I have done my share of laminate inspections as a certified failure analyst, but have never come across anything with sealing tape on 2-n-1 underlayment, or poly/plastic moisture barriers, except the lack of, causing major concerns.
 
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