Insulation, Radiant and Vapor Barriers - Renovating 150 year old house - Need Insulation Guidance

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newyorkn8
05-13-09, 10:16 PM
150 year old salt box farmhouse in Northern New York. Plan to strip every room down to the studs and build 2nd stud wall on exterior walls to thicken insulation cavity - one room at a time, replacing the windows as I come across them. The guidance I need is for the choosing and application of insulation materials.

We removed brick nogging from the stud cavities and after adding the 2x4 second wall, we'll have, from inside-out:

new 2x4 stud wall
existing stud cavity (balloon framing)
sheathing - 2 layers of lapped 1/2 inch boards
wood clapboards

Obviously, vapor barrier and sheetrock are going on the new stud wall, but what should be behind that?

My thoughts were putting open cell foam boards in the existing stud cavities, build the second wall, staple up batts between the new studs, vapor barrier, sheetrock.

My question for this though is, is it OK to have that space between the batts and the foam board? I was thinking of buying thicker batts and scoring them to fit around the old studs, so the space between the sheetrock and the foam board (which isn't thick enough to fill the entire depth of the existing stud cavity) is filled with fiberglass.

Does this seem sound? I know I need to be mindful of multiple vapor barrier layers, and I think I'm good with just the one behind the sheetrock - the foam board is open cell for this reason. I plan to loosely fit the foam board in the existing stud cavities and "glue" it in with canned foam.

Thanks for your input!


atlantarob
05-14-09, 03:53 AM
check out the article "Remodeling for Energy Efficiency : Can a 150-year-old house approach zero energy use? Three case studies point the way from the 19th to the 21st century." by Betsy Pettit
http://www.buildingscience.com/documents/primers/rr-064-remodeling-for-energy-efficiency/
from http://www.buildingscience.com/ (http://www.buildingscience.com/index_html)

Also, search in the Information section of that web site for "cold climate".