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Re: Vapor Barrier[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Vapor Barrier
- From: "Brian K. Smith" <smitheng(--nospam--at)dos.net>
- Date: Tue, 13 Oct 1998 13:12:40 -0500
Jim Kestner wrote: > > I would like to get opinions on what I consider conflicting requirements > regarding vapor barrier under slab-on-grade. ACI 302.1-R, 2.4.1 requires > that if a vapor barrier be used that it be covered with 3" of sand > before pouring the slab. This minimizes plastic shrinkage cracking and > curling. It also controls bleed water coming to the surface. This is > logical and well documented. However, this procedure is risky when > pouring a slab not under cover. What are the chances of rain occuring > after the sand is placed over the vapor barrier but before the slab is > poured? Now, you may have water trapped which could be very expensive to > deal with or if ignored, worse than having no vapor barrier at all. > > It seems like ACI requirements address the finishing and performance > aspects of the slab, but have ignored the practical aspects of what the > contactor must deal with. How do you other Engineers and Contractors > deal with this? > What are the chances of it raining before placing the vapor barrier?? If the subgrade or sand barrier gets wet (saturated) prior to the pour, delay the pour. I personally like using the 3" barrier when possible; however, half the contractors call my office and tell me I have an error on my plans. Brian K. Smith, P.E.
- Vapor Barrier
- From: Jim Kestner
- Vapor Barrier
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