Staggered 2x4 studded walls

[Henry W]

Bob, I would like to thank you for the new sections for the forum. I've been putting lots of thought about a small energy efficient home and I feel staggered studded 2x4 walls would help increase the R value on the walls. I'll post more later.

[LowGear]

This system of framing is also used to separate sound environments as well.  Such as between units in a multi-family dwelling.  I've wondered if placing the studs sideways might enhance their isolation even more?

Casey

[BruceM]

My home is double exterior wall, with staggered studs and a gap between the walls.  2x6 outer, 2x4 inner. The wide wall with gap in the wall also works very well with an insulated, heated (pex) slab, allowing 4 inches of foam board between slab and stem wall.  The inner wall sits on the heated slab. I have 2 layers of 6" fiberglass batts in the walls.  Double wall is fairly common in Canada and works very well.  The extra framing cost is small potatoes compared to the energy savings. 

[mike90045]

This system of framing is also used to separate sound environments as well.  Such as between units in a multi-family dwelling.  I've wondered if placing the studs sideways might enhance their isolation even more?Casey

But would the walls loose a lot of structural integrity?

[LowGear]

Hi mike90045,

That is a consideration until you do some visualization.  My version of stagger stud walls is a 2X6 top and bottom plate with 2X4 studs laid out on 24 inch centers from both sides so you end up with a stud every 12 inches and lets remember that the wall also has a cap plate to compliment the top plate.  This amount of wood when compared to 2X4 on 16 inch centers is significantly more.  The double plates transfer the load to the second and third floors.  If you're not stacking your walls with your joists then you should hire someone to do your drawings and layout.

The staggered stud wall that Bruce M described knocked me back in my chair.  WOW!  Now that's what I call a wall.  In the states "double wall" construction usually means the wall sheathing and siding are applied or installed separately.  WOW!  I wonder what the difference between the Canadian double wall and a 8 inch staggered wall with spray foam would be?  I appreciate when you build a house you expect to live a big chunk of your life has a difference cost effective quotient than does a "spec" or "track" house.  Unfortunately this isn't really appreciated in the states.

I'm also hearing that fresh air to heat exchangers are fundamental to healthy  tight houses.

Casey

[BruceM]

Two separate walls eliminate the thermal bridging at top and bottom plates, as well as at windows.  Plus it allows the inner wall to sit on the warm floor with no bridging to the hot/cold foundation (block stem) wall.  My house temp rises only 3 degrees F on a 100F day despite crappy aluminum windows.  My new neighbors home is using this two wall system and triple pane/argon/low E vinyl windows for even more performance improvement.  For us it means no AC needed, a very big savings in energy system costs for our off grid homes.

While staggered 2x4 studs would be an improvement, I suspect the use of 1.5 or 2" foam board on a 2x6 wall would be superior.  In the Phoenix area, plasticized stucco over foam board over 2x6 became popular in custom homes in the 1980s.  It dramatically reduced AC costs.

I think air to air heat exchangers are a very good idea for conventional homes; you are stewing in plastics (carpets and paints and furniture and drapes) and plasticizers- the stuff that causes endocrine disruption and shows up in your blood. Flushing the home with outside air, without loosing your heat/cool is way cheaper than your future medical/medication bill.  Ask any Environmental Medicine physician.

[dieselgman]

+1 to all said about thermal isolation between inner and outer walls plus AirHandler to provide adequate ventilation for a healthy inside environment. I have long worked in the building trades in Alaska... including a lot of work in remodel insulation renovations for arctic environments. The overall physics of heat transfer apply equally to retaining heat vs rejecting heat. Double walls are common enough for super-insulation.

There are also other options that can work out as well and be much lighter for use in micro-housing. We have used structural foam panels - up to 9" thick. These are sometimes plywood structural frames and sometimes 18ga steel frames cast within the foam sandwich. What you get is both an extremely solid structural performance combined with the superior thermal performance of closed-cell foam in a lightweight panel, basically prefabbed walls you can put together like building blocks of any given size. Since the foam is heat expanded into the voids, the panels become ultra-solid and thermal performance is also exceptional.

We often used a manually controlled 4" (thru-wall) Scandinavian vent device for each occupied room, especially for kitchen and bath, to help control moisture buildup. Low-tech and very effective. The problem with super-tight housing is often condensation... properly controlled ventilation and a proper super-tight vapor/air barrier (inside for winter, outside for summer) is a big part of maintaining a healthy environment. Condensation is your enemy as it gives rise to mold growth and other unhealthy and destructive conditions.

dieselgman

[David Baillie]

for canada with our tight house standards a heat recovery ventilator is a must.  I use a venmar here. At low speed it cycles between heat exchange for 20 minutes and recycling for 40 minutes. The air passes through a core that exchanges the heat from stale air to fresh.  It uses about 40 watts an hour so during the day when we are walking around the house , opening doors and leaving for the day I put it on a timer to shut it down completely.  If you were doing it for a tiny home I would do a tube in tube setup with two muffin fans.  Condensation is those small spaces would be a killer in a cold climate.
David Baillie, Journeyman Carpenter, efficient house enthusiast.

[RJ]

+1 to all said about thermal isolation between inner and outer walls plus AirHandler to provide adequate ventilation for a healthy inside environment. I have long worked in the building trades in Alaska... including a lot of work in remodel insulation renovations for arctic environments. The overall physics of heat transfer apply equally to retaining heat vs rejecting heat. Double walls are common enough for super-insulation.

There are also other options that can work out as well and be much lighter for use in micro-housing. We have used structural foam panels - up to 9" thick. These are sometimes plywood structural frames and sometimes 18ga steel frames cast within the foam sandwich. What you get is both an extremely solid structural performance combined with the superior thermal performance of closed-cell foam in a lightweight panel, basically prefabbed walls you can put together like building blocks of any given size. Since the foam is heat expanded into the voids, the panels become ultra-solid and thermal performance is also exceptional.


dieselgman

When I built my home in Vermont I used SIPS on the walls used 8" and the roof was 12". It was a small home 28x40. It made for electrical work that was a but of a PITA.