Why anyone would build with code minimums today in a cold climate is beyond me.

If you aren't going to live there long, it is typically the best economic choice.

Posted By eric anderson on 08 Jan 2013 07:33 PM
Don't forget that code requirements are minimums, kind of like graduating with a 2.0 in school. Why anyone would build with code minimums today in a cold climate is beyond me.

YMMV

Eric

Unfortunately 98% of all builders in the USA do code minimum. That is the reality of it. If they can find ways to cut corners, they will. All the homes going up today in my area are all code minimum, I have yet to come across a home that is going above code. The only way a home goes above code minimum is when it is a custom home and the homeowner plans on living there for a long time.

Posted By Lbear on 08 Jan 2013 04:03 PM

Posted By Dana1 on 08 Jan 2013 01:23 PM

From an ICF point of view it hardly matters, since all but the most minimalist R16  ICF meets or exceeds code in zones 1-6, and it's not a big bump for zones 7 & 8.

Exactly. For the 99% of all ICF's that are used today, the 2.5" EPS x concrete x 2.5" EPS will pass the 2012 IRC all the way up to Zone 8. The 2012 IRC recognizes mass wall benefits.

Yes it recognized the benefits, but that recognized benefit is pretty slim in zones 7 & 8.  Code requires R21 if more than half the R is on the interior, but is only relaxed to R19 otherwise, even if ALL of the insulation is on the exteror. 

That's only about a 10% difference in U-factor. That is also about the difference the performance of EPS vs. iso under ASTM C518 conditions versus it's performance at typical mid-winter design conditions in zone 7:

EPS labeled at R19 will be performing at about R21 in mid-winter in a US zone 7 location (at the typical average temp through the foam, 70F interior temp), whereas iso labeled at R21 under ASTM test conditions would be performing at about R19.

Yet R21 iso on the interior would still meet code, despite lower-than-labeled performance in that climate.

 So it's a somewhat meaningless distinction there- only in much warmer climates are those distinctions real enough to matter.

An R21 (5" total of EPS) minimalist ICF would still meet code-min there, but barely, and isn't a particularly high-R high-performance wall for the climate.  The code doesn't recognize all of the other fun-stuff that ICF vendors like to hype (like the R-value of the concrete, gypsum, siding, and air-films) to come up with bigger R-values, only the insulation itself, and only the ASTM C518 test performance, not up-rating of EPS performance in very cold climates.  The dynamic mass performance reduction in energy use may be measurable, but it's miniscule in those climates.  Anything that would be considered a high-performance wall starts at R40 (whole-wall) in that kind of climate.  (The GBA guys call R40 whole-walls with similar upgrades on other assemblies a "Pretty Good House" for zones 5 & 6.)

Gotta say I don't see much point in thermal mass north of zone 4 or east of the Pecos unless you have some other reason to pour concrete. The east of the Pecos business is more complicated though. Super insulated houses have a similar problem with humidity, namely that the AC doesn't run enough.

having been down the path with ICF, SIPs, double stud, exterior foam, etc...I landed on ICF in zone 6. However I throw out the mass arguement for my area....dont buy it, never have. Cost wise, since I build and poured it, the price was about the same as double stud and blown cellulose, so called super insulated I would have also framed myself. Additional air sealing details are also required with wood framing. The ICF I chose gets me a pretty much r30 overall value. It has a 2" concrete core, which plays into my belief (or lack there of) of thermal mass in a heating dominate climate. My reaons for going ICF were simple: easier air tightness and tightness I can trust over the years. ICF doesnt rely on caulks and tapes to keep joints tight (except around openings of course...). No water worries, mold, etc. Strong wall (tornado alley, have already been through several in my short life time), quiet wall. Continuous insulation, strength, and tightness from footing to roof. I dont bicker with what Fox, ORNL, code, whoever claims. Sometimes its easier to look past the "data" thats floating out there and focus on what is best for you and yours.