[Greenbuilding] Insulation Problems

[J Messerschmidt]

Hi Listers,
I have a 2 story house under construction, framed and sheathed, with no 
windows yet in Queens, NY.  It's a renovation only by DoB standards.  Some 
of the foundation is still there, otherwise it's new construction.  Don't 
tell anybody.  No thought had been given to green building or building 
science until now.  The outside has been insulated with 2" Dow styrofoam, 
but every 24" going up the wall is a horizontal z clip, attached to the 
sheathing, where the bronze panel cladding will be attached.  Is that a 
clear description?  So the profile from the inside out is 2x6 wood studs, 
3/4" plywood, some kind of rubber painted onto the plywood that could serve 
as a vapor/air barrier, and 2" styrofoam, cut every 2 feet going up the 
walls, with z clips in between, and then the bronze siding.

Can't take any of that off and start again, so I'm figuring the space 
between the styrofoam and the rubber, as well as the space between the 
styrofoam and the panels would have to serve as the drainage plane. Question 
1: Can I count this r-10 styrofoam as part of the whole wall r-value?

Question 2: For the inside, we are thinking of spraying open cell foam in 
the wall cavities to prevent air flow and increase the r-value.  If we 
installed 1" rigid with no foil, behind the sheetrock, I think this would 
block conductive heat loss and would not add another vapor barrier.  Do you 
think this would work?


Thanks!



John