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# Posted: 1 May 2021 11:09

Hello all. Beautiful wife n me are planning on building our retirement home. Yeppers lumber cost will get get me.
I am planning on double wall construction. Gets chilly in Ak. I was thinking 2x6 and 2x4 or vice versa. Then research led me to 2x4 and 2x4 inner and outer walls. Single story so compression strength wouldn't matter. I was thinking cost of framing would be considerably cheaper.
I was thinking a 2x10 top n bottom plate. Does anyone have experience with this design for residential housing ?
Currently we're looking at 28x40 .
Or a good forum web site I can get info from. I have been looking at Ak cold climate center.
Thanks all

# Posted: 1 May 2021 11:40

Have you considered the other way around by building an Advanced Framed homes using 2x6 walls with a 1" thermal break between studs & sheathing ?

The thermal break (high density foam) prevents the exterior cold from leaching the warmth out and prevents external heat (summer) from being drawn into the building. The rest of the insulation between studs could also be spray-foam or even sheet foam or Rockwool (Fiberglass is not suggested at all).

A thermally broken wall can be extremely efficient and reduced overall building operating costs significantly as well it does not complicate construction too much.

Siding installation can be accomplished in various ways BUT if installed like a proper Rainscreen Fashion it can also act as an additional Thermal Break. BTW: Just because the "method" is called Rainscreen don't assume it applies only to wet rainy areas... I'm in the Deep North as well.

# Posted: 1 May 2021 14:46

An acquaintance built a house like that in Moab about a dozen years ago. Double 2x4 wall framing. I visited once in the hot summer and it was remarkably cool inside. Their heating and cooling costs were extremely low.

You do not need anything bigger than 2x4's. A two story house can be safely framed with 16"OC 2x4.

I do not recall how the top plates were made or connected. A solid top plate that completely spans the distance from inner wall to outer wall might not be necessary and using one introduces a thermal bridge.

A friend here has built a pumice-crete home. Google that. The walls are about 24 inches thick IIRC, and are cast in place concrete that uses pumice as aggregate. Very light weight. Pumice is full of air spaces and can float in water. The walls were formed with reinforced sheets of plywood and filled with pumice-crete. Then the forms moved horizontally or vertically to pour the next section. That house also has a very low energy use for heat and cool. NM has areas with lots of readily available pumice. The exterior is stucco and much of the interior is old fashioned hand troweled plaster. Some T&G pine that we milled from onsite timber. It took some planning to allow for chases to be cast in for pipes and wiring but it is very impressive. Concrete perimeter foundation (we only needed 24" deep) and a well insulated concrete slab floor.

# Posted: 1 May 2021 22:47

What R value are you trying to achieve? 2x6 wall r24 and 2x4 is r12=r36
You can frame 2x6 put r24 then use 2” silver board thats r10 and get r34 with a lot less framing and less space needed.
Get trusses built with a large raised heel and blown in atleast r55. Make sure to spend the extra on triple pane windows

# Posted: 6 May 2021 12:30

Thanks all. Things are starting to come together in my head. I like the idea of 2x6 with spray foam insulation. And back in the 70s I was working for a crew building homes using 2x4 wall n 2" of blueboard over them on the exterior. Back when most folks were using colored Masonite siding with color matching nails. We had to use a plastic cap on the hammer to not damage the paint. There weren't nail guns then. Achieving a thermal break.
From bottom up. Footers , kinda sandy soils so compaction is required. I build footers 16" wide to accommodate a compactor. 4 foot tall 6" wide poured concrete foundation wall.
For floor joists 12" , TJI-BCI manufactured joists. Topped with 3/4" TnG. Vapor barrier on dirt floor of crawl space ran 18" up foundation walls. Rim joists n interior walls of crawl space will be spray urethane. Sealing Vapor barrier on floor. Basic stuff.
Then it gets interesting. Assuming I used 2x6 with spray urethane for wall insulation. Lay out the exterior bottom plates and internal walls. I will be installing basically a double bottom plate cinareo. Nail in all the plates with acoustic caulk under outside plates.
Should look like a house with no wall studs. I'm doing in floor hydronic heating. So lay down some material like rolled reflex on the floors. Then lay in the heat tubes. No heat under the kitchen cabinets, n such. Then float the whole floor with light weight cement. Should end up with a flat floor with the lower wall plates exposed. Each room will have its own loop or thermostat.
I still have the desire to watch a flame dance it's glow through the house n beautiful wife is right about getting older. So I'm going to put a fuel oil drip stove in the living room. They make them look like wood stoves now n use no electricity. We'll have a genny for back up power also.
Toyo makes a fuel oil fired hydronic boiler combined with on demand hot water. That will be the primary heat source.
Walls, current thoughts are. 2x6 with a 2" thick insulation board like blue board. Spray urethane between studs. That gives me a 2" thermal break surrounded the home. I will use 2" blue board down past the sill plate on the foundation wall.
Roof trusses with a 5/12 outer 3/12 inner Scissors trusses.
I have used a unique design for my n sons house. Inn cord of the truss comes down to interior wall. Then a 4' horizontal area, top cord of truss meats that part then a 2' tail. So I have a 6' dripline. And an energy heal of over 24 " . On my current home the trusses span 40' with no interior support and used this design. No evidence of truss flex in 25 years. No cracks in the sheet rock. A tip here, don't nail closer than 2' to the wall , let float, kinda..
On insulation, all I can achieve. Every dollar spent on energy lost is a dollar saved.
On windows, triple pane gas filled. Kinda thinking something different here too.
Adding storm windows. Now that's dating myself. But should increase r value similar to putting up plastic shrink film window stuff. It works well in our current home.
Probably outside the box to in thinking shingle roof. I just get tired of the steel roof look. The roof will be designed to handle the snow load. Onour current home each side of the roof is about 32' wide n 38' long. When a foot of snow comes off you wouldn't want to be under it.
Anyhows kinda long but times fly n there's lots of good folks with great ideas here.

Thanks all

# Posted: 6 May 2021 15:58

Quoting: Steve_S
Have you considered the other way around by building an Advanced Framed homes using 2x6 walls with a 1" thermal break between studs & sheathing ?

Easiest and cheapest.

# Posted: 8 May 2021 12:06

Thanks, I don't know what advanced framing is. But I think that's what I am doing. Walls will have spray urethane between them. And 2" of blue board foam insulation on the outside of the stud. Probably seal joints
On siding I'm thinking wood. But nothing nailed in yet 🙄
Thanks all, I appreciate all comments

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