Thermal break with saw cuts through stud
 

I realized today that I could get my skilsaw into most of my wall cavities and cut a slot in each stud.

Even better would have been a plunge cut before framing.

I'm not sure if the gap needs to be very large but I bet if I can get a strip of 1/2" foam in there I'm good. To make a bigger gap I could drill a hole top and bottom, cut two slots on either side of that hole and cut out the waste with the jigsaw.

I saw this as a sound control measure in an old carpentry textbook. Double your utility with the slot method.

As long as it's not a load bearing wall you are fine, but most outside walls are load bearing walls and with how lumber is graded and the movement of the grain cutting your studs in to twin 2x2's will really weaken the wall.
Why it works for sound deadening is that most partition walls where you want sound deadening are not load bearing, I've seen some partition walls in houses built out of 2x2's... not the best idea, lean on the wall and it can bend and flex.

Most of the walls I'm doing not load bearing and have been upgraded to 2x6 so structurally they should be fine.

If I cut the 2x6, what would be the best offset? Outside, inside or a mid cut? I guess it's a trade off but should the priority be sheathing attachment strength or drywall stiffness?

I think that sheathing should get the greater structure, its not going to be as cheap as sheet foam, but caned expanding (great stuff) foam will help stiffen any cuts you make, of course it will also bridge the thermal gap you created, giving a greater R value then the wood had but not as good as the air gap, best would be a reflective insulation in the gap and in the stud space.

I'm not understanding this. Pictures?

I'm ripping the studs in two, creating an air gap, so that there is less heat conducted to the outside wall through the stud. It will also help reduce noise transmission which is great because we live near the tracks and get a lot of freight through here

I have a lot of Reflectix I can use for the gap. That's because it was the only insulation in the cavities of these walls. I guess someone had an exaggerated idea of it's r-value.

~1000 words.

https://picasaweb.google.com/m/viewe...63925072597458

Can't upload from my phone:(

I would suggest that you leave a small bridge (maybe 1") of wood every foot or two to act as a beam web. This will greatly increase the strength of the studs without losing much in the way of R factor.

Ideally for insulative purposes it would be to the outside of the wall, since you are in more of a heating area, than a cooling area. However structurally the best place would be toward the inside. That said if you have the walls apart anyway look at what you can do to increase their sheer strength. By separating the drywall side from the sheathing side of a wall you do lose some sheer strength, it sounds a bit crazy I know but drywall is a part of the sheer structure of a typically framed house. Also look into just adding a 2X2 interior wall separated at the sill plate, that will eliminate almost as much thermal bridging as you possibly can, increase the amount of insulation you can put in the walls, and likely be less labor intensive and thus cheaper than cutting every stud in the wall.

Even adding half inch of ridged foam over the studs will help with thermal bridging without making the room much smaller, foam also helps a great deal with sound deadening.