Stop a Balloon Frame House From Swaying
I am currently in the framing phase of a deep energy retrofit gut rehab of 3 story 1880s balloon framed home in zone 5 (Chicago). I have basically spec’ed a platform framed house to be built within the existing balloon frame with the idea that we would be able to add insulation and it would give addition strength to the building.
This past week as been a windy one here and my framing contractors informed me that the house is swaying more than they are comfortable with even after the interior shear walls were added. They are recommending 2 inches of closed cell spray foam for the exterior walls to add rigidity and strength. The existing plans call for the following wall construction
Drywall
8 inch cellulose
original clapboard sheathing
Henry Blueskin
3 inches of Neopor GPS foam
Rainscreen
Siding
My fear is that adding the closed cell foam to the inside that the walls they won’t be able to dry (from my understanding GPS has more drying potential than EPS but it is pushing the limit at 3 inches). Does anyone have have recommendations on stopping the swaying other than closed cell foam, or does anyone think that the walls will be able to dry effectively even with that closed cell on the inside?
Replies
You refer to the interior walls as a shear walls. But are they resisting shear force (wind)? What is mechanically coupling the inner wall framing to the original ballon frame? If the two are, or can be structurally coupled, letting diagonal bracing into the new wall should stiffen both walls.
Mike - That is a good point - I'll check that out this evening. I found the website below that details a new build that is very similar to my retrofit as far as construction goes. I'll look to have these studs tied together like this and hopefully the next windy day it won't have that same sway.
https://prudentliving.com/affordable-zero-energy-homes-a-balloon-framed-wall-does-it-all-2/
In New England older houses have "Queen Knees" braces or short diagonals made from 4x4 size stock or like the previous comment diagonal wall bracing with as long of a length as possible and kerf studs so its rugged and use structural screws like Head Locs instead of gun nails more tensil stength. There is also metal bracing that goes into a saw kerf but only 8'
I missed something here- why is a balloon framed house from 188o's swaying? did you remove the orginal sheathing/bracing? Also where are the Architect's drawings that provide the specs would answer such questions? Such drawings would be required here [PA} before a permit was approved.