Project > Design
Wall Construction: ICF, SIPs or Double Wood Wall?
If we're going to build an affordable energy efficient home the very first question is "What do we build the walls out of?" Before we get into the options, let's look at what is typically built in our climate.
A typical new home is built with 2x6 studs spaced at 16" and the cavities filled with R20 fiberglass batt insulation (minimum insulation as required by the building code). When considering the conductive heat loss through the wood studs, this wall performs at R17.7 overall. We deemed this to be far below what should be built for the climate of the Canadian Prairies because, yes dear readers from warmer climates, -40 degrees celsius is typical in the depths of winter.
The alternatives we examined included:
1. Insulated Concrete Forms (ICF) - R22.4* EPS Foam Insulation
2. Structural Insulated Panels (SIPS) - R17** EPS Foam insulation
3. Double Wall Construction - R24 to R60 and above, many insulation options
There is a lot of debate about the merits of each building technology, which generally serve to confuse the customer and builders alike. ICF claims benefits due to thermal mass in their walls, SIPs claim air tightness and heat retention, both claim that fiberglass let's too much air into the wall cavity. While I do not refute these claims, I have yet to see a direct comparison between these technologies and a double wall construction (Thermapan has an excellent case study with a standard 2x6 wall).
Despite these points of debate, we have decided to go ahead with a double wood stud wall because of the flexibility and materials used: skilled labour is plentiful, insulation levels can be increased infinitely, and the materials are low energy, potentially recycled and locally sourced. Our goal is to continue increasing the R value as long as the additional investment produces savings above our acceptable limit of 9% return.
My only hesitation to pursue a site built home is related to the quality control of the finished product and the waste created along the way. Factory produced products are inherently lean and efficient, minimizing material waste along the way, and we will have to take extra measures to minimize our waste given our decision to build wood framed walls.
All things considered, we are convinced that this strategy of a double wood wall design will help us to deliver a Shift Home that is equally green and affordable. Our next installation will address some of the details of our double wall construction.
* Nudura, 6" concrete core, finished with vinyl cladding and gyproc, as tested by Bodycote Materials Testing Canada
** As published on Thermapan website
Write a comment
Posts: 10
Reply #11 on : Tue January 17, 2012, 11:30:04
Posts: 10
Reply #10 on : Sun January 15, 2012, 06:23:41
Posts: 10
Reply #9 on : Sat January 14, 2012, 22:52:25
Posts: 10
Reply #8 on : Fri January 13, 2012, 03:20:55