Is R30+ possible in a 2x6 Exterior wall for Canadian winters?

Fran6

Hello,

We're planning on building our first home next spring. (Early April)

We are wondering if it is possible to get a solid R30 rating in our exterior walls.

Note that we are also debating if it would be worth the money to invest in a double 2x4 wall setup to achieve our insulation goals.

Thanks in advance

Francis

Stillwerkin

I think the spray foam is rated at 7R per inch. Pricey, but it stops all the drafts and fuel prices aren't going to go down. You can buy DIY kits or have a company do it.

IMO, even a few inches of that with the rest fiberglass would be better than straight fiberglass.

High Gear

Have you considered a SIP constructed home?

http://www.solarhomesus.com/view_pura_vida

I had a chance to talk to the owner and builder when this was being constructed and I went through it after completion , very sharp individuals.

Gary in WA

http://www.buildingscience.com/docum...-climate-house
Be safe, Gary

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itsreallyconc

why would anyone still build wood when sip's OR icf's are available & so easily used,,, we'd NEVER build stick again - our next home'll be icf - r50 walls,,, even down here in ga, heating & cooling costs're significant,,, btw, our choice has nothing to do w/environmental issues - its ONLY based on $$$,,, the 5% addl we'll invest by using icf's will be amortized in 12 mos,,, from then on, its $$$ in our pocket

Bob Mariani

itsreallyconc....
And this option gets you $1500 back as a tax credit. That is a dollar for dollar return.

ccarlisle

If you are building new in 2010, it makes a whole lot of sense to look into what itsreallyconcrete says about SIP building - in other words building to R2000 standards, especially up here in (my home town). If your going to be spending money building a home you have to look not only at actual building costs but future maintenance costs as well.

R30 in the wall is easy to achieve but it's not just the insulation R-value that's important up here...sure, more is better but at what costs with traditional building materials like 2x6s? While you're at it why not go for R38? or R50?

Have you been to the R2000 website?

Fran6

Looks like I have more reading to do

Thanks guys! I'll look into everything you said and will keep you all posted.

Cheers,

Francis

ccarlisle

Put i another way, R38 may be achievable - but not with products you buy from Lowes. Spray-foam isocyanurate panels can get that high I think, but they come at a cost.

With 2x6s, you can fill the wall cavity as much as you can - and may not reach R38...the solution is to apply insulation on the outside as well, and that means dealing with air infiltration considered by many (me included) more important up here than R-values.

We're from Rockcliffe Park...

Fran6

Yes, well obviously the R value is important and we're trying to be at least R30 or more for our walls, but I agree that putting insulation on the outside walls is very important. Now, we're looking at installing a board and baton sort of exterior finish....how much/thick foam panels can we use on the outside.

As for the cost....we know we'll need to invest more money up front but we're positive that we can get that money back in the long run. We are settling for this house and we're planning and staying there for the next 30-40 years.

ccarlisle

How thick the outside insulation panels are is a function of the specific siding you are putting on. 1" or 2" is possible with polyisocyanute 2x8, or 4x8 sheets. That can add R7 per inch thickness.

So R14+R19 should do it...are you building this yourself?

Bob Mariani

Read the latest FineHomebuilding magazine. They have an excellent article on R40 walls. How to make them for new construction and for retro fits. There are several methods and cost versus benefits are discussed. One issue is controlling air infiltration and controlling moisture migration. These work hand and hand with insulation methods.

Gary in WA

I haven't read the article Bob said, so I may be repeating. If replacing the siding, go with the foam AND a rain-screen system. A lot less perforations in the air barrier as ccarlisle said: 2 sidings:

http://www.greenhomebuilding.com/pdf/RainScreen.pdf

http://www.nchh.org/Portals/0/Contents/Article0440.pdf

http://www.coastalcontractor.net/article/135.html
Be safe, Gary

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