Stanley

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

BCConstruction

As long as there's good insulation between the internal walls and external walls then you should stop most if not all condensation issues.

Stanley

thank you very much

NJ Brickie

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.

tomstruble

when did tar paper become a vapor barrier?

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Tom

WarnerConstInc.

Since they said it was

NJ Brickie

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?

tomstruble

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

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

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Tom

loneframer

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.

NJ Brickie

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?

tomstruble

to me the only thing in that assembly that is a vapor barrier is the foam

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Tom

loneframer

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.

NJ Brickie

Thanks for the info. Like they say you learn something new very day.

loneframer

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.

tomstruble

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

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Tom

loneframer

I thought you were the pro here Tom, now I have to rethink everything I thought I was sure of.

tomstruble

your a nice man

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Tom

Red Adobe

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