Thursday, February 28, 2013

Interesting + Informative dialog on implementing USA New Wall & Swedish Platform Framing

We had this dialog via our Facebook Page this week, and I thought it hit on several common questions about building with USA New Wall & Swedish Platform Framing today, as in right now - not some point in the future when all that is wrong with house building in the US is fixed.

NM: I am a small builder and am interrested in the Swedish Platform and USA New Wall framing. I am curious though if you have any photos or information on how the electrical is installed in the electrical space. Does the electrician need to do any special? Thank you for any information.

LamiDesign: Nothing special really Nathan. If you are using a 2x wiring space then you would use a 4x4x1.5" box, with a switch plate reducer cover - that will extend the 1/2" to the surface of the drywall. The 4x4 box actually has a bit more room inside than a typical single gang new work box, and being shallow makes the electrical work a bit easier IMO. The boxes can be screwed through the back to the main cavity studs, or through the sides into the cross furring - so there are actually twice as many options for where to mount them.

Now if your wiring chase is deeper you may need to shim the box out, or use a deeper box - this would be driven by the sizing of the ledger member. What I mean is, if your floor spans are longer you may want to use a 1 3/4 ledger rather than a 2x. That would be a ledger from a PSL or LVL rather than 2x lumber. So that slightly deeper chase throws off the nice fit of a 1.5" box. For me I think a better option is to notch your joist ends, and lift your 2x ledger up flush with the bottom of the joist, and supplement the bearing with a short joist hanger. With plate nailed trusses they can likely build that notch right in for you. If you are using I joists, then a full height ledger with joist hangers may be easier, but creates more thermal bridging. Official spec for I joists will require 1 3/4 bearing, but 1.5" works fine for small spans IMO. But both those options keep the wiring chase at 1.5".

NM: Thank you for the information, pretty simple solutions really. Any cost analysis on how much more this framing adds compared to traditional Western Platform Framing? I have frequented your website for a few years now and am a fan of your work, a nice change from the norm.

LamiDesign: No - I don't have any cost data. The insulation can be awkward to install at best - working the main wall cavity below the first floor level, and above the ceiling level requires shoving behind a previously installed vapor sheet. You have to apply the vapor sheet in strips that overlap the floor before the floors are in place.

It would be nice if you could insulate the main cavity before tilting the wall up, but this gets into conflict with your framing inspection. If you use Membrane for the vapor control layer, its completely transparent - you could apply it over the whole wall and you can still see the framing, albeit with the insulation in the way. The Proclima product is not transparent, so there is no good way to apply this over the whole wall ahead.

There is no way around these sequence issues, and this is where cost is raised more so than materials. This is why the Swedish Platform Framing really lends itself to off site building.

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