Double Stud “Deep Wall” Framing

The day following the completion of the excavation, backfill, grading and dirt hauling, Taylor and Curtis with EcoSmart got to work framing the double-stud exterior walls. We had chosen to use the “deep wall system” originally developed by Rob Dumont, a local Saskatoon engineer who is widely recognized as one of the pioneers of super-insulated green building. He has been a major inspiration to the owner of EcoSmart Developments, Murray Guy.

Rob Dumont had been one of primary engineers in creating the Saskatchewan Conservation House – which is one of the original homes that inspired the German Passivhaus movement. This is a fantastic article about Rob Dumont’s own home that he built in 1992 using his deep wall system (it was considered to be the most energy efficient house in the world at the time!).

Saskatchewan Conservation House, 1977
Rob Dumont’s personal home

Rob Dumont developed this super-insulated wall system and Peter Amerongen from Edmonton AB has been perfecting it over the past few years, using it in the Riverdale NetZero and the Mill Creek NetZero homes, amongst others. To my knowledge, no one since Rob Dumont himself, has built another home in Saskatchewan using this type of wall system. I’ve written about this wall system previously, but now we were going to see it come to life before our eyes.

Taylor and Curtis had of course never built this type of wall before, but they had done extensive research and were very motivated about it. This wall system utilizes two 2×4 walls, spaced 16″ apart thereby creating an 8″ void between each 2×4 wall. There is no need to offset the studs as the large void, which will be filled with dense-packed cellulose (recycled newspaper), has no thermal bridging whatsoever. We elected to space the 2x4s at 16″ centers for both the interior and exterior walls. It is possible to space the non-loading bearing wall at 24″ centers, but when attaching the wood siding to the exterior wall (our non-load bearing wall) this might be a little more tricky.

Of course this wall system takes a bit longer to construct then your typical stick-framed house, as each wall needs to be built twice. What the guys did was to lay the lumber one on top of the other to ensure that the spacing was appropriate. The studs were nailed together with a double bottom plate (we will be pouring 1.5″ of concrete for the main floor so you another bottom plate was needed in order to secure the drywall to it) and a double top plate. The two walls were then secured to a 16″ wide 3/8″ OSB header and footer and tipped up into place using wall jacks. The walls were then glued and nailed into place and sheathed on the outside.

The first day they framed the west wall which is 30′ in length. Honestly, the excitement of seeing a wall could not be contained that day.DSC_0316

Side door with transom overtop
Side door with transom overtop

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Day two they framed the north side which is a longer 48′ wall with minimal penetrations – one window in bedroom, one in the hall for ventilation and the back door.

Day three was the west wall, again 30′, which included three large windows (energy efficient geeks will note that there is minimal benefit to large windows on east side and there is risk of overheating in the Spring and Fall) however these windows look onto an amazing river view that we had to enjoy. The windows will be glazed in a special coating to reduce heat gain (more on that later).

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Looking east to the river
View from the kitchen sink
View from the kitchen sink

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Main entrance and foyer corner window
Main entrance and foyer corner window (tricky detail)

Day four they ambitiously completed our southern wall, our primary 48′ wall, with three MASSIVE windows – all of which are more then 10′ wide – and a patio door to the deck. This side of the house looks onto a beautiful southern view across the river valley, but also will be a source of heat gains in the wintertime.

Four walls!
Four walls!
HUGE south windows
HUGE south windows
Dining room corner window
Dining room corner window
Framing details
Framing details
Corner window framing details
Corner window framing details

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Next would come the interior walls and roof – and suddenly this was looking like a house!

3 thoughts on “Double Stud “Deep Wall” Framing

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