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Discussion Starter · #1 ·
:clap:HI
any experience with this installation:
Existing stucco, then building paper,then frame of 2X2 every 16" with
1 1/2" "studs" and styrofoam in b/w
More building paper on top
Then vinyl siding
Besides hard to nail or glue the 2X2 and styrofoam is there any other side efects?
like dew point -condensation ,mold?
Location -Vancouver -Canada close to Seattle
Getting read of the stucco is not an option, and personaly I think it will add an R value to the house insulation but I am not a 100% sure about condensation
I have to do it in the next 2-3 weeks
Tx
Stanley
 

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I maybe late on this but 2 layers of building paper with wood in between sounds like it maybe a problem. Moisture tends to get caught between two layers of vapor barrier.
 

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Maybe I am missing something. I'm not a carpenter nor do I claim to be. Why has tar paper been used under siding if it is not a vapor barrier? There are many books that list asphalt coated paper as a vapor barrier. What am I not understanding?
 

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actually its relatively vapor permeable,its the preferred house wrap of the Loneframer and many other craftsman on this site:clap:

vapor barriers are of the poly sheeting type that are relatively impermeable to water vapor
 

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KemoSabe
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Maybe I am missing something. I'm not a carpenter nor do I claim to be. Why has tar paper been used under siding if it is not a vapor barrier? There are many books that list asphalt coated paper as a vapor barrier. What am I not understanding?
Tar paper actually has a good resistance to moisture when it is dry. As the level of moisture rises, it expands and becomes more permeable. In the presence of high levels of moisture it has more of a tendancy to act as a wick and draw moisture through. Some people see that as a drawback, but given proper flashing details and siding tecniques, I see it as a positive, as it will allow moisture between it and the sheathing to pass through and evaporate more readily, as opposed to nonperforated housewraps, which only allow water vapor to pass back through, slowing down the drying process. Perforated housewraps have very poor test results to moisture resistance.:thumbsup:
 

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I do know that tyvek type materials are the preferred, better technology. Tar paper is an old way of wrapping a stick framed house. But in the situation the OP described do you think it would lead to rot?
 

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KemoSabe
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I would be most concerned with the possibility of the chemicals in the paper having an adverse affect on the foam panels. I'm told that is why you won't see felt used with a Dri-Vit type system.
I agree with Tom that the foam would be more of a vapor barrier, unless it is perforated like fanfold.
 
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KemoSabe
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Maybe I am missing something. I'm not a carpenter nor do I claim to be. Why has tar paper been used under siding if it is not a vapor barrier? There are many books that list asphalt coated paper as a vapor barrier. What am I not understanding?
Asphalt coated kraft paper, such as what is used in kraft backed insulation is a good vapor barrier because it doesn't expand in the presence of moisture, as felt paper will.
 

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KemoSabe
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thats for sure NJ, i have to rethink alot of the things i thought i was sure of after talking with the pro's here:thumbsup:
I thought you were the pro here Tom, now I have to rethink everything I thought I was sure of.:blink:
 
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I do viynl but I'd much rather have EIFS myself but thats just me.

I wouldnt suggest nails or glue for furring or the foam....screws are the better way to go. Use them 2' plastic eps washers on foam
 
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