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Huh? leaks vs. condensation 101

Posted by jb on August 2nd, 2000 03:18 PM
In reply to water barrier by Harold Kestenholz - Hydronic Network on August 2nd, 2000 02:26 PM [Go to top of thread]

I am assuming that there is no water coming in to the basement through the ground. Where I live it is code to seal the outside of the concrete wall to prevent this migration. From my experience moisture in basements does not come from the ground as you say, unless it is unsealed, or leaking. It comes from condensation most of the time. How do you stop warm, moist air from meeting cold surfaces and condensing? Voila! insulation and vapor barrier. Throw in some dehumidification for good measure, and you have a livable space.

You write: ..."Moisture as a vapor (humidity) passing through concrete (it is porous, unless sealed) will collect on the cold surfaces"... This is absurd. How does water as a vapor pass through concrete, by magic? Your posts really don't make much scientific sense.

You also state: ..."Tyvek wrap IS placed on the OUTSIDE of the house to let moisture in the wall pass through and not collect in a cold impermeable sheet of plastic. It can do the same job in another place."... Tyvek is there primarily to stop drafts. It DOES allow any moisture in the form of vapor to pass through. There shouldn't BE much moisture if you use a vapor barrier on the inside of the insulation (or on the outside if you live in the tropics). The moisture in the form of liqud water comes from DIFFERENCES in temperatures leading to condensation. If you stop the vapor in the warm air from contacting the cold surface then you prevent condensation. As I said in my previous posts, if there is water leaking into the house from the outside this isn't a good idea. I wasn't talking about magical pixy water vapor somehow passing through a solid. If I run into that situation I will be sure to call your company first thing. Otherwise I will steer clear of your vague unsupported musings. Did you just make up all that stuff just to get us going or can you please show us anything to support your strange theories?

Actually, I just saw your other posts that supposedly offer "proof" and I pulled this quote directly out of one of them
..."you still should put an interior vapor barrier over the furring before you hang the drywall. This vapor barrier should stop the moisture traveling from within the laundry room to the foundation walls. If the barrier were not in place, this humidity could condense on the cold concrete - and the barrier you installed under the insulation and furring would trap it within the wall"...

The article vaguely reffered to "capillary action" as "wicking" moisture from the outside, but this won't happen if your foundation is sealed and it certainly isn't as vapor as you profess. The other article is talking about how to tell if what you have is a leak or condensation. This is a good tip, but it hardly bolsters your Tyvek theory and is pretty basic stuff.

OK, we have established that there are leaks and there is condensation as possible moisture sources. If there are no leaks then having a VAPOR BARRIER should stop condensation. Why would you put Tyvek that costs a lot and doesn't stop vapor? You still haven't told us.

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