[Greenbuilding] Exterior wall construction--Again!!

[Lynelle Hamilton]

One version of Durasol has roxul in the outer side of the cavity. Don't 
know if/how much this helps.
I've been told that insulating on the inside doesn't work with passive 
solar designs, as the heat in the wall will radiate to the colder 
(outer) side, not indoors.
If the foam is sealed to the outside wall, doesn't it eliminate the 
bridging?  Then, use the permeable barrier?

Thanks again!

Lynelle

Ward Edwards wrote:
> The best method to attach the fibre cement board would be to attach 
> strapping to the exterior with screws that can reach through the foam 
> to the durisol or block (you would have to use tapcons or similar for 
> the block) and then the fibre cement could be attached to the 
> strapping with roofing nails (you need something with a large head).
>
> You would probably be better to put the foam on the inside and seal it 
> as your interior vapour barrier as you want it on the warm side of the 
> wall.  On the exterior, you want a vapour permeable surface so that 
> trapped moisture can escape the wall.
>
> To attain R40 in your wall, if just using foam, you would need 8" of 
> XPS, as it has a rating of R5/inch.  The durisol or block filled with 
> insulation would have the problem of a lot of thermal bridging.  I 
> looked at Durisol when I built, but eliminated it from consideration 
> due to cost.
>
> Ward Edwards
> http://www.ownerbuilder.ca
>
>
> Lynelle Hamilton wrote:
>> I'm building on waterfront and am looking for the exterior wall 
>> "assembly", if you will. When John spoke of the 'wetness' of the 
>> PNW.  I suspect I'll be similar.
>>
>> The wall core is as follows:  Durasol or Concrete block (if block, 
>> cavities filled with insulating material)  cladded with foam on outer 
>> wall, then...what??  A friend, who developed a type of ICF, says just 
>> to put fiberglass mesh over the exterior foam and then stucco, that 
>> the foam is the vapour barrier.  I don't know about stucco at the 
>> waterfront, and  have toyed with the idea of cement fibre panels.  
>> Stone (other than the "artificial" stuff) is not a possibility, 
>> except possibly for a partial wall.
>>
>> FWIW, slab is poured concrete, insulated as much as I can.
>>
>> With cement fibre panels come the need to somehow attach them 
>> (through foam).  From all the discussion on this site, I now have no 
>> idea if these panels are OK and if it good or not to try to attach 
>> through the foam.  Also, what depth of foam do I need to attain R40 
>> or better in the wall?
>>
>> Any ideas or suggestions as to where to research?  I'm building 
>> pretty much on my own (as is obvious from my questions)!
>>
>> Thanks
>>
>> Lynelle
>>
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