Last night’s TOH episode reminded me that this is something I want to do either before the summer gets too hot, or next winter too cold.

My question is on my balloon-framed house, when insulating the walls where the 2nd floor, floor joists meet the outside walls, how to prevent blow cells from leaking horizontally into the joist cavity.  With the settling I hear about with cellulose, I feel this might make it worse and would compromise the insulation value of half the outside walls.  I know for a fact these are open b/c I had the baseboards out a year ago when I was running new wire upstairs – wish I’d thought of stuffing some FG or foam in there while I did…  That by itself might’ve made the house much tighter.

My thought was to make a hole to spray some expanding foam from one of the DIY spray foam kits, to block up the end of the cavity. 

PJ