[Greenbuilding] Water Barrier

[Peter Kidd]

just a conceptual word of caution, neither air nor water leaks need to 
line up literally, but especially not air leaks. And as others have 
said, air vapour water and thermal barriers are all different things 
although one product may do some or all, at least as a material if not 
as a system. some of those air barriers you mention for your multiple 
layers are also vapour barriers so you can't really speak of non vapour 
air barriers and 'vapour air barriers' as one and the same thing, at any 
given set of conditions at least.

> I was not seeing the extent of liguid threat to building with siding 
> blocking the wind driven liquid rain. However, I have observed that 
> when eps is exposed to prolong soaking such as in an exterior 
> foundation insulation where poorly drained, it will hold water like a 
> sponge.
>
> Thanks for input.  Adding the building wrap is a pretty low cost way 
> to decrease my risk.
>
> Does any body see risk for multiple air (non vapor) barriers?  I 
> understand the risk of trapping liquid between multiple vapor 
> barriers.  However, my thinking is that just an air barriers will 
> allow drying to the warm side even if one has leaks in the barrier.  
> Because so much of the performance for tightness hinges on the 
> execution of the air barrier, I tend to want several layers of air 
> barrier, such as sealing osb seams, sealing foam seams, taping foam 
> seams, et.  Chances are all of those may have some execution flaws.  
> However, to leak all the way through they would need to line up with 
> flaws on other layers.
>
> Eli
>
> -----Original Message----- From: John Straube
> Sent: Saturday, March 02, 2013 6:16 PM
> To: topher at greenfret.com ; Green Building
> Subject: Re: [Greenbuilding] Water Barrier
>
> Exactly.  And Tyvek is Gore-tex for buildings.
>
> On 2013-03-01, at 10:46 AM, Corwyn <corwyn at midcoast.com> wrote:
>
>> A water barrier is designed to keep *liquid* water on one side of 
>> it.  A vapor barrier is designed to keep *gaseous* water on one side 
>> of it.
>>
>> Often a water barrier is purposefully made to NOT be a vapor barrier. 
>> The common example is gore-tex clothing.  It keeps the rain out, but 
>> allows the vapor of evaporated sweat from the occupant to escape.
>>
>>
>> Thank You Kindly,
>>
>> Corwyn
>>
>> -- 
>> Topher Belknap
>> Green Fret Consulting
>> Kermit didn't know the half of it...
>> http://www.greenfret.com/
>> topher at greenfret.com
>> (207) 882-7652
>>
>> _______________________________________________
>> Greenbuilding mailing list
>> to Send a Message to the list, use the email address
>> Greenbuilding at bioenergylists.org
>>
>> to UNSUBSCRIBE or Change your List Settings use the web page
>> http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org 
>>
>
> John Straube
> www.JohnStraube.com
>
>
> _______________________________________________
> Greenbuilding mailing list
> to Send a Message to the list, use the email address
> Greenbuilding at bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org 
>
>
>
>
> _______________________________________________
> Greenbuilding mailing list
> to Send a Message to the list, use the email address
> Greenbuilding at bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org 
>