Insulating old house
I just joined here in hopes of getting some input on my house insulation.
I have purchased a 1925 home in Roanoke Va , climate zone 4a. It is a brick veneer with approx 1.5″? or so air gap between sheathing and brick on first story and it is a variety of stucco called pebble dash on second floor. I want to insulate the never before insulated house but the more I read Im getting nervous as to the proper approach. I have intentions to use Blown in loose fill probably from the inside. I realize that these walls have been getting plenty of heat througout its 100 years and I am getting ready to retard that heat, and thusly abiltiy of wall to dry out. The first floor i feel ok to insulate , because of the air gap the second floor is a different story. I am thinking to knock off stucco (no easy or fun job) and get to 3/4″ 1×8 with. At this point install wrb and 1×4 nailed to studs for a pretty normalish rain screen assembly. then remove all exteroir casing and jamb extension windows. Then install hardie plank. does this sound ok regarding condensation in the old walls? Am I barking up the right tree? I have also heavikly considered a manufactured rain screen house wrap that could possibly eliminate the need for jamb extensions due to its thickness. Anyhow any help is greatly appreciated, go easy on me please, relative newbie trying to do my best. Will gladly furnish more info if needed and I can!
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Just to clarify terms, the insulation product you're thinking of using is "dense-pack" cellulose not "loose fill" cellulose. Loose-fill is for horizontal areas where shifting of materials is unlikely, dense-pack is for applications where the contents need to withstand an external force (usually gravity, like in an exterior wall cavity).
Your stucco exterior has lasted almost a century (I assume it's original) and it would be a large expense to replace it with rain screen/cement board as you've described. I'm not qualified to summarize, but check out "Assessing the Impact of Thickness on the Performance of Stucco Cladding" published in 2004. They did some research on the permeability of traditional stucco applications and it might help you become more comfortable with dense-pack behind the existing stucco finish/board sheathing.
Perhaps someone else has more information on insulating behind traditional stucco, unfortunately it can be hard to sift out the good research in this area from all the EIFS related issues.
Before you tear off the stucco, you may want to have a local builder with experience working on stucco homes take a look at the house. If there are no existing water management issues (no leaks), roof overhangs, flashing where it is needed, no major cracks in the stucco, the house has sheathing, etc., it may be fine to insulate the stucco-clad walls with cellulose. If some of those problems exist, perhaps they can be remedied. Stucco houses in colder climates that yours are often retrofit with insulation without a problem. But I would suggest having someone with experience take a look at the house before proceeding.