Attaching the furring strips when there is 4″ of Continuous foam
AproLLC
| Posted in Construction Techniques on
In trying to build an efficient home, looking for suggestions or those with experience with thick levels of foam user on the outside of the home.
My wall calls for 2 layers of 2″ polyiso so 4″ overall. As I do believe in the air gap as if one reads the manufacturer’s recommended install, they state to have the gap with any engineered or composite siding. Thus I need 1/2″ air gap with sum furring strips.
My question comes to how to attach the strapping if you have 4″ of foam. the screws would need to be at least 6 inches. Would the wall continue to hold the weight of the siding or at that distance is there enough sheer potential? looking to thoughts / comments.
I have done this with 2″ of poly with nails, but the 4″ has me questioning if something more is needed.
Replies
Hi there, I am not a huge fan of these envelope designs. I'm all for energy efficiency, but not for the incredible pragmatic inefficiencies and deficiencies they can create. I won't rant here however! Haha.. Look into 6" headlock screws. They are "engineered" to have the sheer, resistance to bending needed for furring and siding.. I still don't like it really.. common sense says leverage will act dramatically on the end of a 6" screw that isn't supported for 2/3 of it's length... How about 2" of exterior foam over a double wall filled with dense pack instead?