What would you do? XPS or EPS or ISO?
I am building a 3000 sq foot home in northern ontario (zone 8 or 9) with about 9000 HHD.
I am weighing my options on this wall contruction type.
It will be a 2×6 frame with R24 blow in batt in wall cavity and exterior foam insualtion, 1×4 strapping and siding
After reading and calculating foam thicknesses(thanks Martin) I would like to get to R20 if possible for the foam giving me a total wall R40+ rating, will be detailing like a REMOTE wall (window bucks)
Assume all of these will be taped:
I have been able to find EPS 5″ thick(R20) non faced – plain white stuff
OR 2 layers of 1.5″ ISO (foil faced) for a total of 3″ (R18)
OR 2 layers of 2″ xps for a total of 4″ (R20)
Now the $$$ part
EPS is about $3500
ISO is $9500
XPS is $11,500
If i go with EPS, would i need to cover it with a WRB?
THere is a Labour saving as well with EPS as it’s only 1 layer, but no offsetting joints – just taped
– the other 2 options would have offsetting joints, is that a concern?
What would you do?
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