Double Stud Wall Framing for Passive House

The interior comfort level with double stud is A+, in my experience. Love it.

Great video, Steve. Thanks for sharing this one

My son has been building double stud walls for a few years now. Outside wall is 2x4 16” on center and that wall is spray foamed. 2” gap and than inside wall again 2x4 16” OC but of set 8” with exterior wall and that gets Rockwool insulation. Now for a question I have for you. Have you had drywall screw heads start showing up over time? First 3 houses he did, so he came to me and asked way that might be happening. I thought about it for a bit and figured out that the inside stud wall was twisting because nothing on the back side stopping it from twisting. Put blocking half way on wall and next 4 houses and no problems so far

Thanks for the detailed explanation!

Great content Steve. Are the numbers crunched to see what more cost effective putting added insulation on the outside or as you did in that house. A double studded wall. I like the double studded approach. Wish big red can show some cost comparison.

Hello Steven! When you have the opportunity, would you please expand your explanation of the possibility of a double negative of a thicker a 24" double wall in a cold climate. You commented something about making the exterior side of the wall colder and the possibility of greater issues. Your content is greatly appreciated and I have watched all of your videos. Thanks for sharing! Always liked and subscribed... 👍👍👍👍👍

For the recessed windows, are you doing nail on to a 2x that's connected to the sheathing? or are they blockstyle windows connected directly to the sheathing on the inside of the window buck you've designed? ( LOVED THIS VIDEO!!, amazing details!)

Puzzled why you'd go to that much effort for a 3" gap when you could add a whole lot more so easily - especially when the common studs aren't even offset from each other, so at every stud you literally only have that 3" gap. Upgrading even a little bit, to say a 6" gap, and having the common studs offset so they're not so close to each other, would give you a much better performance for zero extra effort.

Question: Would it make sense to stagger the inner and outer studs, potentially increasing the thermal break from three inches to 6.5 to 8.5 inches, in most stud locations? Or is this effect negated by something else? Great video.

Love your video! QUESTION: to be clear, is the 3" thermal break filled with cellulose? Also, isn't he true weighted average R-value of the wall significantly reduced by the large window?

Great video, thanks! Hey, do you have a favorite type of house building method I.e. wood, metal, ICF, concrete or concrete block etc.?

OR you could try the following . my house is a log/block house . the laminated 'logs ' are 14 cm thick with 14 cm of wood fiber insulation on the outside followed by verticals furring strips and wood paneling over that . the space in between the FS acts as an air vent to remove any moisture build up . no vapor barrier is necessary as the entire wall assembly is vapor permeable . The mass timber on the inside regulates humidity and tempeture swings making for a very comfortable atmosphere . The air blower test was almost at a passive house level . No air to air heat exchangers are necessary as the entire structure is non toxic and non off gassing. opening a window for five minutes is sufficient to refresh the room . heating is done by a two ton soapstone down draft oven . A three hour burn is enough for two days at 72 degrees or warmer at 32 degrees outside . The exterior walls can be erected in about two days including g roof framing . the lower labor cost offsets the higher price for the timbers .

That was great coverage on dbl stud walls Steve! And glad you talked about how the "dew point" moves within the wall assembly and having to pay attention to potential condensate. I was wondering your view on offsetting the 2x6's and 2x4's centres (ie by 12")? Effectively that would produce greater depth of insul in the cavity between the two walls (ie., 6-1/2" of insul between the inside face of a 2x6 and the vap barr / drywall, and 8-1/2" of insul from the front face of a 2x4 to the exterior sheathing, respectively). Obviously most applicable on long running walls, but do you think that would add materially to the R-values, rather than simply a consistent 3" thermal break? Worth the bother?

A lot of people naysay about putting OSB on the outside of a double stud because of its relatively low permeability. Do you see that being an issue at all or is that overblown? Will this walk use a vapor control membrane on the interior to slow moisture drive during heating seasons or is it fine without one?

So…where’s the fire stop required in most areas?

Informative as ever Steve. But I have a question. Lets assume the same thickness of insulation is included in 2 different wall configurations. Along with the same interior and exterior finishing layers. Number 1 wall is the double wall as shown here. Number 2 wall is a standard 2x4 wall with 3.5" of insulation within it and the remaining thickness of insulation is applies to the exterior. Is there any advantage to No1 over No2? To my mind Number 2 has a better thermal break and a lot less lumber so will also be cheaper. Also as a potential owner builder with little framing experience I think No2 would be easier to build. Or if I did get framers in at least I'm only paying for one 2x4 frame to be built? Whats your thoughts? TIA

Staggering the interior framing members so they don't align b right behind those in front of them on the exterior wall will also make the wall more efficient.

Like it but could you use Zip R9 with 2” closed cell foam, then 4” RockWool in cavity, A vapor barrier, then the 3” of cellulose? Can this eliminate condensation and have higher rated insulation over long term.

Can you add exterior insulation to this wall to stop the problem of the sheathing getting cold?

Steve, what factors should be considered when choosing between these two 12" double-stud walls: 2x4+5" gap+2x4 OR 2x6+3" gap+2x4?