Can there be a high efficient house built with walls 3.5 inches thick?

Vrooman said:

This house is going to be a high efficient house, as like all the houses we build.

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If it is a exterior-wall-bearing, double-exterior-wall house. That would be an R50 wall (leave 5.5" space between the walls.

For this house it will be a 2x6 exterior wall with 2" of extruded polystyrene outside.

That's a lot of lumber!!

Vrooman said:

If it is a exterior-wall-bearing, double-exterior-wall house. That would be an R50 wall (leave 5.5" space between the walls.

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Gottcha. :thumbsup:

Are you familiar with :
http://www.amazon.com/Building-Affordable-House-Fernando-Pages/dp/1561585963#noop

He goes into a lot on OVE which is where 24" framing came from right? Also I believe he goes into a lot of issues with thermal bridging like corner design especially.

Also in the last issue of Fine Homebuilding I believe there is an article about 6 different ways to build energy efficient wood walls.

http://www.finehomebuilding.com/des...-to-build-energy-smart-walls.aspx?ac=ts&ra=fp

Vrooman said:

For this house it will be a 2x6 exterior wall with 2" of extruded polystyrene outside.

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It is somewhat common in high efficiency home building in Canada. its only 33% more lumber than one wall framed 16" on center for the studs

WarnerConstInc. said:

That's a lot of lumber!!

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A single top plate usually means you need a gusset to connect 2 pieces together on a long wall. Not unusual, but definitely not common.

1/2" sheetrock as opposed to....what? Do you use anything other than 1/2" sheetrock? I think it would be spongy unless you use ceiling board or 5/8". Just my opinion.

Usually the ply is 1-1/8" and it should be fine. Span ratings for that usually say you can go 4' centers which sounds absurd to me, but again, I'm sure it's done. I used 1-1/8" DFir once before and that was one solid floor.

Vrooman said:

I have been thinking about trying 24" centers on exterior walls with a single top plate, for a house coming up this spring. This house is going to be a high efficient house, as like all the houses we build. So I am trying to come up with as many ideas to eliminate thermal bridges as possible.

It meets code, and if the trusses land on studs, I see nothing wrong with it.
I was thinking if we do this, 1/2" SR would be better for the drywall.

I have also heard you can build a stronger floor with 24" centers and 1.25" plywood than 16" centers and 5/8" plywood.

Just looking for some input from you guys.

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Didnt know about the gusset plate, but makes sense. I will have to check the code and see if anything is specified for that.

1/2" SR, as in Sag Resistant drywall intended for ceilings.

I think the hardest part of this would be educating the inspectors that there are alternative ways to build that still meet the intent of code.

Thanks for the input

framerman said:

A single top plate usually means you need a gusset to connect 2 pieces together on a long wall. Not unusual, but definitely not common.

1/2" sheetrock as opposed to....what? Do you use anything other than 1/2" sheetrock? I think it would be spongy unless you use ceiling board or 5/8". Just my opinion.

Usually the ply is 1-1/8" and it should be fine. Span ratings for that usually say you can go 4' centers which sounds absurd to me, but again, I'm sure it's done. I used 1-1/8" DFir once before and that was one solid floor.

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Sorry, you typed 1/2" SR, I thought the SR meant sheetrock. Your SR is our ceiling board. Same product.

The book "Building an affordable house" has a lot of information on framing efficiently including single plates, 24" o.c. framing, omitting headers on gable ends, etc. There are some important rules to follow but one can significantly reduce the amount of wood going into the structure.

The book also goes into how to deal with the plan checker and the building inspector when faced with this very different type of framing.

I think in our IRC 24" o.c. spacing is only permitted on the second floor of a 2 story house or on a single story house if the wall is only supporting a roof above it, I might be wrong though I don't have the code book on me. Have you already planned to do the california corner's at outside corners of the house?

What is a California corner?
We usually do an L-corner, but have also been thinking about drywall clips, but don't have any experience with them

Yep, a California corner is an L corner. Umm I used the clips once on a habitat house and didn't really like them but I don't know how people with more experience with them feel about 'em.

One of the builders in Fairbanks (Jack Hebert) has been doing "Remote Wall Construction" with great success. He utilizes 2x4 walls, vapor barrier on the exterior over sheathing, 2 to 6" of blue-board, furred out with 1x4 then covered with siding of choice. Has some positive benefits such as high R-Value 30-50 depending on amount of rigid insulation, very tight house requiring an HRV but most high efficient homes that is a standard and for us with moist climates or extreme cold weather it moves the dew point to the exterior of the home thus eliminating the potential for moisture in the wall cavity. Of course there are some cons, of which the two that come to mind are cost and "It's something new" were as getting your Building Official to buy off on it. Were this applies to your question is that it does utilize 24" framing centers to save on the amount of lumber. The other option is a double wall yet that does require more lumber. As mentioned, as long as the floor or trusses are over a stud should not be an issue but that is up to the engineer on record.



Go to www (dot) cchrc (dot) org. This will take you to Cold Climate Housing & Reasearch Center. They have statistical data, manuals and other data regarding this. I threw in an attachment to show a few examples. Something Different.

Our state is offering energy rebates up to $10,000 for upgrades. My house is not to efficients so this summer I will be doing a retro with 4" of blueboard along with sealing up air leaks that I have. Just have to find the time to do it.

Vrooman said:

If it is a exterior-wall-bearing, double-exterior-wall house. That would be an R50 wall (leave 5.5" space between the walls.

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Have you looked into SIP panel framing?

I want to say our wall value is R-50...We have a complex roof so we stick framed our roof conventionally, with closed cell spray insulation. OUr insulation contractor will spray our hidden rafters (not cathedral) to help eliminate the thermal break, and makes for a very tight envelope.

I really wish I knew all the specs....code for roofs here was 42, may be 48 now. I think 1" foam is R-7....we're spraying 7"

If nothing else, I hope this gives you another option to look into....I don't believe the route I described is any cheaper than other methods.


For our SIP project we only invested in a Prazi "chain saw" attatchment, and a "hot knife". SIP is relatively simple to construct.

There were a few SIP panel homes built here locally but due to the cost of getting material up here I have not seen any done recently. Cost, especially shipping, kill us up here for material.$225 a yard of concrete, $48 for 3/4 T&G subfloor, well you get the picture. With that said the SIP homes I have been in are pretty darn tight and well insulated. The other problem we run into regarding the roofing panels is the snowload, wind and sesmic requirements. But it is diffently another option to look into.

I have also seen a few homes up here built with 2x8 walls - 24"oc. Seen those skim coat with a couple inches of spray foam then remainder of space filled with regular batts. Still does not address the thermal bridge regarding the studs and inside/outside temperature difference. Hence another reason why steel studs just have not been to popular up here. A double wall with staggered studs would eliminate that along with the SIP and REMOTE setup.