For the Beekeeper's Bungalow we've decided to build what is often referred to as a Swedish or Scandinavian Wall. This type of wall calls for horizontal furring strips to be installed throughout the interior of the house typically at 24″ intervals (see illustration). In light frame construction, furring strips are just long thin strips of wood (or metal) used to make backing surfaces to support the finished surfaces in a room.In the past we’ve insulated our houses with traditional fiberglass, open cell spray foam (Icynene) and even some cotton. More recently, we began considering natural sheep’s wool from Oregon Shepherd and mineral batts manufactured by Roxul. For our current project, The Beekeeper’s Bungalow, we chose a type of fiberglass insulation, the Knauf Ecobatt, touted as “greener” than standard fiberglass insulation products because it contains a higher content of recycled glass bound together with inert organic plant polymers (as opposed to formaldehyde and/or other toxic glue chemicals).
The benefits of this type of wall are well worth considering, especially if a breathable insulation is going to be installed. Why? Well, for one it enables a single piece of insulation (e.g. a fiberglass batt) to be fully inserted into a stud bay without being interrupted, and therefore compromised, by electrical wiring, gang boxes, plumbing and other systems. Secondly, it allows a vapor barrier to be installed continuously over the studs and insulation – once again without being compromised by protruding electrical boxes, etc. The results are walls that greatly reduce air and moisture migration.
But that’s not all…
You’ve probably also gleaned that there’s also an additional 1-1/2″ space for insulation. This is yet another benefit of furring out walls. Okay, it’s not a vast amount of space but it’s something, especially in a cold climate where every inch of insulation counts. If you’re willing to incorporate, say, rigid board insulation, you can add up to an additional R-9. Add that furring to the exterior as well and you’ve got up to an additional R-18! In addition, all that furring reduces thermal bridging to the small points where the furring crosses a stud.If the furring strips are 2×2 in size then it’s also possible to use the open space between each one as a chase to run electrical wiring. If the electrical project is planned well, then smaller, correctly sized gang boxes can be installed directly onto studs without puncturing the vapor barrier. To do this all that needs to be done is a simple unit calculation to determine the required volume per box (most standard sized boxes are bigger than necessary anyway). Any electrician worth his salt will be able to properly size your electrical boxes as a matter of course. Also, a good up to date wiring book from the library or Amazon.com should have this information as well.
If you choose to build a Scandinavian style wall, keep in mind that the International Residential Code requires fire blocking every 10′ both vertically and horizontally, so you’ll need to install blocking (more furring) at these locations. Not a big issue but don’t overlook it.
I’ll also mention that in Scandinavia, notably Sweden, balloon framing, which utilizes long continuous framing members (i.e. studs) that run from the sill plates to the top plates, with intermediate floor framing let into and nailed or bolted to them, is far more common than it is today in the USA. Historically, many houses built in New England and across the country before the advent of Western Platform Framing (1800′s) utilize balloon framing. Balloon framing still has virtues worth considering. Why, you might ask? Well, when floor joists are bolted to corresponding studs the overall strength of a structure is greatly improved and can be expected to handle high winds and earthquakes more effectively than standard Western Platform Framing, which end up with weaknesses (hinges) between systems that can fail during lateral pressure. Also, blocking might still be required between floor joists in a Balloon framed house but the need for a rim joist is eliminated, thus reducing thermal bridging further (hey, you insulated behind your floor all the way to the exterior sheathing!).
And a Few Words About Balloon Framing…
And for all you outspoken patriots and moderns out there – before you decide against balloon framing as a foreign import or an outdated design – you should know that code builders are beginning to again warm up to balloon framing, especially when engineered wall and floor systems are to be used (true: engineered walls of any sort benefits the construction lobbies).
In sum, a fully employed balloon framed Scandinavian style wall has many benefits and is gaining some popularity. It might not be long before it’s again detailed and unabashedly encouraged by code. For more details, visit architect Gregory La Verdera’s blog. He’s a talented and outspoken modern architect with Lami Design who employs his own style of Scandinavian wall designs. He’s even developed his own type of insulated wall called a New USA wall.