I just wanted to mention that many Colorado counties (if not all) have gone over to the new residential insulation building codes.  That is, walls were a minimum of R-19, are now a minimum of R-21.  Ceilings were a minimum of R-38, and are now a minimum of R-49.   That means that a 2X6 wall with R-19 batt insulation won’t pass code, and it will be more expensive to build a stick built home than before.  And, a SIP home that meets these local codes, is now much more competetive in price to a stick built.

 

Steve

GrandCountySIPs.com

Hmm, guess you didn't get the memo that fiberglass makers have offered a high density R21 batt for several years now because of said code change.

Not saying thats a good thing, but your attempt at increasing market share on that point appears to have come to a dead end. Sorry to be the bearer of bad news.

Compare the price difference between the R-19 fiberglass insulation per sq/ft with the high density R-21 fiberglass insulation per sq/ft. You will find that the high density R-21 insulation costs about 50% more. If you want a vaulted ceiling, you will need wider rafters to accommodate thicker batts of insulation, or go with the higher priced high density fiberglass insulation. Or if you want a conventional ceiling, you will need more blown-in cellulose insulation. Bottom line, it’s now more expensive to build a stick built home than it was before. The only bad news is for those that build a stick built house that’s still not as energy efficient as a SIP home.

Steve
GrandCountySIPs.com

The best-case as-installed per manufacturers instructions R value of R19 batts is R18(!). In 16" o.c. framing with a 25% framing factor its an R14 whole-wall R (after thermal bridging.) A best-case perfectly installed R21 batt is R21, and in 24" o.c. framing comes in at R15.

But that's using 75F as the center temp for an ASTM C 518 test. When it's 0F outside the R15 wall with the high density R21s will still be performing close to R15, maybe as low as R13, whereas the low density R19 batt wall is performing about R10.

And that's best-case, perfect installation, in a lab. In the real world all batt installations underperform spec by at least 10%.

A cellulose blown (any density) into a 16" o.c. 2x6 wall is also about R14 for whole wall R, but is very stable over temp, and with blown insulation real world performance is pretty close to lab performance. Add 1" of exterior XPS sheathing and it's R19. Add 2" of XPS ( or 2.5" of EPS) and it's ~R24, but performing closer to R26 when it's 0F outside.

A minimalist R16 ICF will run about R17 at 0F outdoor temps, but about R14 at 100F outdoor temps (but the thermal mass usually helps out big time on those days.) In places that require R13+5 (~R15 whole-wall) or R19+7.5 (~R20 whole wall) construction as code min, the code-min for mass-walls is usually R16, and the performance as measured in the heating/cooling energy use is pretty comparable. An R20 SIP has a slight performance advantage over R19+7.5 in places with large diurnal temperature swings, but in the bigger picture it's not that much- adding a half inch of foam above code min on the stick built evens it out for all but high-desert type environments.

Rigid foam sheathing on a cellulose-filled stick built with the structural sheathing detailed as a primary air-barrier is almost always a more favorable price/performance compared to ICF, if looking only at thermal performance, even if you have to go to 10-15% higher on R value to make up for dynamic mass effects of the wall. With any wall assembly, once you're at R20+ whole-wall values the windows start to dominate the heat transfer through the walls.

SIPs are even lower thermal mass than stick built and get no dynamic benefit allowance, so if R21 cavity fill is code min, a 5.5" EPS SIP (~4" of foam) would have similar ~R15 whole-wall performance (due to lower fraction thermal bridging elements.)  But a 2x4 w/R12-R13 cellulose-fill with 1.5" of exterior iso would buy you ~R20 whole wall performance at the same 5.5" thickness, usually for less money.  The 5.5" SIP would do slightly better than the no-foam 2x6 R12 wall at the cold extremes due to the negative temperature coefficient of the R value of EPS, but it would do slightly worse at the summertime peaks (lower, R, lower mass.)

But this is at code min.  Anybody who is looking only at code min values on things isn't really taking the long term view on value.  In most of Colorado there's a 25 year present-value financial argument for R25-R30 walls if done with best R/$ method,  even higher if the only heating fuels available are propane or oil.

Steve,
I get your angle, but for the sake of healthy discussion is a fiberglass batt stick house really the competition of SIPS?

I would think sips as a botique high performance building system that would compete with hybrid stick frame systems and icf, not production stick frame, dont you?

Someone looking at standard construction who has to pay $125 more for wall insulation (high density batts are maybe 20% higher here BOX store prices) and maybe $200 to go from R38 to R49 in the attic for cellulose, that's not going to cause them to look at SIPS. This trend becomes evident if you have followed home buyer trend survey's in Builder magazine, consumers just don't care yet what there walls are and they are leery of small market share building systems.

I guess my .02 would be increased energy codes are not the magic bullet for SIPS, as is evident by the number of hybrid stick threads on this site. The status quo lobby keeps the changes within grasp of their own capabilities. Maybe a national production builder needs to adopt a SIP division or maybe some SIP mergers need to take place and panel costs need to get slashed for sake of market share. I think once the ball got rolling it would be hard to stop but it's kind of like the celliulose vs fiberglass industry.

I'm with greentree- R13+ 5 is an acceptable substitute for R21 in 2x6 in most local codes, is relatively easy to air seal, and usually a lot cheaper than a 5.5" SIP. R13+ 10 outperforms a 5.5" SIP and can still be done more cheaply in most markets. Batt-insulated stick built isn't the competition for SIP, but blown/sprayed cavity + foam sheathed stick built often is.

Standardized home designs and mass production might bring costs down and make SIP more viable to the mass market, but for the time being it seems custom designs at the higher end of the market and high(er) performance buildings is the only place where SIP has much traction.

Yes, they should specify "R19 @ xx degrees F".

... and as-prescribed by the installation instructions!

Low density R19 batts perfectly installed in 2x6 framing only deliver R18, center cavity, at 75F and a 25F delta-T.

Low density R22 batts designed for the same 2x6 framing deliver only R19, best-case, and the labeled R is bordering on fraud, IMHO.

(This is according to the manufacturer's own published data!)

R21 high density batts deliver labeled performance in the 50F-95F outdoor temp range, but still fall off a bit at the extremes, but not nearly the performance loss at the low-density junk experiences. Installed in a wall they perform only slightly better than R19s in the mid-range (R15 vs. R14 nominal whole-wall R), but FAR better at the temperature extremes.

R13 batts are OK in 2x4 framing, but R15 batts suffer less loss at the extremes. R11 batts in 2x4 framing falls into the same category as R19 batts in 2x6 framing- densities too low to hold up over temp, but still better than nothing.

Note, when exterior foam is used, the temp at the exterior side of the batt stays closer to the mid-range, and loses less performance to convection within the fiber. In R13+ 10 wall (1.5" of exterior iso) the steady-state temp on the outside of the batt at the center point between the studs, with 70F interior, 10F outside temp is about 34F, just outside the 25F delta-T of the test used for labeling. (If it's 2" of XPS instead of iso it'll be closer to 37F.)