To poly or not to Poly?


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Old 05-03-06, 06:46 PM
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To poly or not to Poly?

I am pouring a slab on grade for a workshop that will be heated at times in the winter. Do I need to lay down 6 mil poly on top of the fill before I pour or leave it out?
 
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Old 05-03-06, 06:57 PM
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Yes, poly.
 
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Old 05-03-06, 06:59 PM
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Is this stricly to keep the concrete from sweating?
 
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Old 05-03-06, 07:03 PM
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It is to keep moisture from penetrating the slab from underneath.
 
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Old 05-03-06, 08:06 PM
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To poly or not to Poly?

As Tscarborough correctly pointed out, the poly is a vapor barrier that prevents the transmission of soil moiture through to the slab surface. It is negligible cost and does wonders.

"Sweating" is the condensation from the room air that occurs when the cold soil temperarures are transmitted through the concrete to cause condensation. This is normally not a problem where you have reasonable temperatures and decent soil temperatures.

By eliminating the vapor transmission with a vapor barrier, you are not adding to any possible moisture and you should not see moisture on the slab.

Dick
 
 

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