No vapor/air barrier?

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No vapor/air barrier?

Postby MrRee » Fri Jul 03, 2009 4:22 am

I've been reading a lot of informative posts about building walls, but none seem to suggest that vapor/air barriers are being used in the walls or floor. Superblock, double-walling, and the like is great for insulating against direct heat conduction, but does not do much (it seems) to prevent moisture from floating in between the pours. In the States, a non-permeable barrier such as a plastic-type sheeting or even drywall is the norm. What is being used in Thailand construction? Anything? Thanks in advance for comments/suggestions.

My reference: http://www.wrmeadows.com/data/cat-mm03.pdf
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Re: No vapor/air barrier?

Postby Jack » Fri Jul 03, 2009 8:15 am

For the floor in my single story house I used plastic sheeting as a vapor barrier under the slab. And I poured a monolithic slab. I didn't worry too much about the walls for several reasons. The stucco/rendering, good paint, and wide eaves work well against rain intrusion. I didn't worry about condensation because the my walls don't get the type of temperature differential that would encourage condensation. There are very few days when I don't have my windows open for at least several hours and when I run the AC the outside/inside temperature difference for my comfort zone is not that great. So, for me, the only vapor barrier I worried about was in the slab.
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Re: No vapor/air barrier?

Postby dozer » Fri Jul 03, 2009 9:54 am

As Jack stated.... It is a good idea to use plastic sheeting, the type they normally sell is very very thin clear plastic which tends to tear super easily during the pour of the floor. I've had better luck with heavy black plastic sheeting (comes in rolls) purchased at Global House. It should be used to protect the footings + floor + ground beams. Here in Pattaya houses with no damp course seem to do OK but I've been in places where the moisture comes up and paint will not stay on the wall.

As an extra preventative the CPAC concrete for the floor ground beam can have an extra water proofer added to it for a minimal cost, protects against a tear in the plastic.....

As far as wall treatment and a quote from the attached PDF:
Moisture in exterior claddings, coupled with repeated
freeze/thaw cycles, can lead to spalling of bricks, delamination
of facers, etc. This can be particularly damaging
in the more northern climates where the building envelope
is exposed to multiple freeze/thaw cycles annually.
imagine not as much of a concern here as the climate is different.
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Re: No vapor/air barrier?

Postby MrRee » Fri Jul 03, 2009 6:10 pm

edit: posted as separate thread
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