Mike597 and Lbear. The Federal Trade Commission, which has policed insulation claims since 1980, cracked down many years ago on the thermal mass crowd. (In the interest of full disclosure, AAC manufacturers were making bogus claims as well.) The manufacturers responded as you would want them to respond: They hired accredited independent labs, conducted tests by accepted standards and based their insulation claims on the results. Durisol's work up is here: http://durisolbuild.com/Webdocs/Durisolthermalperformance.pdf

Now some people on this site think r value equivalency is a crock, but it's accepted by ORNL and the FTC. If you think Durisol's numbers are wrong, say so in an email to agency and include the link above.

Now you may ask where is the ICF study and its DEFENSIBLE r value equivalency claims? Sad to say, when the perception is better than the facts, your marketing types congratulate themselves on a job well done and kick the facts under the table. The result here is pro ICF types making unsubstantiated claims about their product and disparaging Durisol's, even though the latter has jumped through the regulatory hoops. Officially, ICF is "better than the house next door." No offense, Mike597, but big whoop.

Posted By toddm on 21 Dec 2011 01:15 PM
Mike597 and Lbear. The Federal Trade Commission, which has policed insulation claims since 1980, cracked down many years ago on the thermal mass crowd. (In the interest of full disclosure, AAC manufacturers were making bogus claims as well.)

Now you may ask where is the ICF study and its DEFENSIBLE r value equivalency claims? Sad to say, when the perception is better than the facts, your marketing types congratulate themselves on a job well done and kick the facts under the table. The result here is pro ICF types making unsubstantiated claims about their product and disparaging Durisol's, even though the latter has jumped through the regulatory hoops. Officially, ICF is "better than the house next door." No offense, Mike597, but big whoop.

From what I have researched, the true R-value of an ICF home (2.5" EPS x 2 with 6" concrete core) is more of a realistic R-22. The only way to get a higher R-Value would be the EPS blocks that add more EPS to the outer portions (Nudura, QuadLock). With a thicker EPS exterior, one can get R-30 through R-40.

I am still not completely sold on the ICF thermal mass. It is really dependent on the climate. I wish there were better studies out there on it.

Polycrete can make variable EPS thicknesses, up to 12" per side. Also any core width from 5" to 12". This is because the steel wire cross ties can be easily made to any length and proprietary molding machines that are quite versatile -- they can even be used as block molds.

"The only way to get a higher R-Value would be the EPS blocks that add more EPS to the outer portions (Nudura, QuadLock)"

I am not aware of Nudura making ICFs with more than 2.625" of eps each side. Maybe you mean Logix.

With a material cost of more than double ICFs, the finished wall is not as strong and r-value of about 1.7 per inch for the majority of the material with the add in insulation for a relatively small portion of the wall. I just don't see the point of using the wood fiber ICFs.

Posted By toddm on 21 Dec 2011 01:15 PM
Now you may ask where is the ICF study and its DEFENSIBLE r value equivalency claims? Sad to say, when the perception is better than the facts, your marketing types congratulate themselves on a job well done and kick the facts under the table. The result here is pro ICF types making unsubstantiated claims about their product and disparaging Durisol's, even though the latter has jumped through the regulatory hoops. Officially, ICF is "better than the house next door." No offense, Mike597, but big whoop.

Todd,   For the record, I think Durisol is a fine product and significantly better than wood.  Remember, Durisol is still an ICF so it's better than whatever else you may be contemplating.  I participated in one installation where the house walls were primarily Durisol and the radius portion only was Nudura.  It went fine but I don't agree with some of the points mentioned earlier about speed etc.  Anyway, that's just my opinion.  

Regarding your comments above.   Kinda little over the top for the ICF forum don't you think?  Why do you like this forum so much anyway?  You've put out a report that doesn't have a date or a laboratory associated with it.  This is not the nature of a regulatory hoops report.   I took the liberty of posting one of the ashrae reports that is likely the source of at least some of the data in the Durisol report you posted.  This ASHRAE report stands to change things in the market since the most efficient school in the U.S. is ICF.   Also,  since you asked, I've posted the lab report for the our R-value.   Regards.


http://www.nudura.com/Libraries/Tec....sflb.ashx

http://www.ashrae.org/publications/...50pct-AEDG

I should have said, I don't see the point, for the majority of the projects. However I am sure there is a percentage of projects that wood fiber ICFs would be right, and I would like to do those.

What about the concrete? Durisol says;
"Because the Durisol is a free draining material, it is possible to use a high-slump concrete (7” – 9” slump) without adversely affecting your concrete strength. When pouring a very wet concrete mix, the Durisol material immediately starts to drain the moisture so that it does not result in weaker concrete, while ensuring that there are no voids and making the pouring process easy."
If too much water weakens concrete, how does their system really prevent that?

Posted By ICFconstruction on 22 Dec 2011 09:35 AM
"The only way to get a higher R-Value would be the EPS blocks that add more EPS to the outer portions (Nudura, QuadLock)"

I am not aware of Nudura making ICFs with more than 2.625" of eps each side. Maybe you mean Logix.

With a material cost of more than double ICFs, the finished wall is not as strong and r-value of about 1.7 per inch for the majority of the material with the add in insulation for a relatively small portion of the wall. I just don't see the point of using the wood fiber ICFs.

Nudura's standard thickness is 2 5/8".  If you want 2 5/8" inside and a 5 1/4" thick outside you have to put 2 5/8" inserts into the block slide into the dovetails.  I don't recommend it and have never done it since your pretty much at diminishing return.   Just to clarify if you still wanted a six inch core you would use the 10" core block etc.   Regards. 

And it is next to impossible to slide those inserts into the dovetails, we did it many times for beam pockets, I can't imagine doing an entire wall.

Polycrete can make variable EPS thicknesses, up to 12" per side. Also any core width from 5" to 12". This is because the steel wire cross ties can be easily made to any length and proprietary molding machines that are quite versatile -- they can even be used as block molds. What thickness do you want?

TexasICF: Attributing much of the high efficiency of a school building to ICF construction is a bit off the mark. Optimization of the glazing design, the R value of the roofs & roofing material selection, and and the efficiency/control of the lighting/daylighting, plug loads, mechanical systems, & solar orientation have a far bigger impact than the thermal mass & R values of exterior walls in that type of building (& use.)

In many school buildings increasing R value of walls beyond a certain can even increase annual energy use due to higher sensible air-conditioning loads. To tease out the performance and make sense of where to spend the money requires a decent energy use model (DOE-2 or better) and an iterative design process. ICF would usually have better structural capacity than low-cost CMU seen in many school buildings, but even a minimal-R ICF can have a higher R than optimal for many climates, sufficient to null any thermal mass benefit. These decisions are site, climate, building-type and design specific- a blanket recommendation for ICF construction in school buildings or commercial construction isn't warranted, even if that was part of the plan for the current efficiency-winner school.

In the "...ASHRAE report stands to change things..." (titled: Advanced Energy Design Guide for K-12 School Buildings ) the short-sheet recommendations by climate zone (see chapter-4) start at R values of mass walls start at R5.7 for zone 1, and is only R13.3 for zone 5 (still a sub-ICF level), but it finally gets to a minimalist-ICF R19.5 only for US zones 6-8.

I suppose that's a change from recommending mass walls only for cooling dominated climates, but it's hardly a prescription for extensive use of ICF in school buildings. (They have other R values recommended for other structural wall types in the same documents.) If anything it's a prescription for only limited use of ICF in said structures.

BTW: ~R15 ICFs as per the ORNL side-by-side house comparison did/do exist, and were common in the '90s, if less so now.  The basement in an addition on my house was done with R16 ICFs sometime around 1997 (and the contractor who installed it didn't bother to clean or bond to the existing foundation where the ICF foundation met up with it, leaving as much as 1/2" of clay in pockets between the new and the old I discovered recentlym, having to chisele it out and repaired it with hydraulic cement to block the seepage prior to finishing off that room. Grrr...)

[quote]
Posted By Dana1 on 22 Dec 2011 11:28 AM
TexasICF: Attributing much of the high efficiency of a school building to ICF construction is a bit off the mark. Optimization of the glazing design, the R value of the roofs & roofing material selection, and and the efficiency/control of the lighting/daylighting, plug loads, mechanical systems, & solar orientation have a far bigger impact than the thermal mass & R values of exterior walls in that type of building (& use.)
[/quote]

I agree that ICF is only one of the pieces in this puzzle. It makes it's contribution just as the other pieces do. This is clearly the nature of this report and that's why I posted it. Along the same lines as you've said in the past ICF brings much more to the table than just energy efficiency. Safer schools for example. Regards.

Not "contribution just as the other pieces do", but rather a very TINY piece of the energy part. From strictly an envelope-design point of view it's the smallest piece of the high efficiency envelope puzzle.

But I'm all for reinforced concrete construction from a durability & sustainability point of view ( ICF or otherwise), and even with sub-optimal R a minimalist ICF will sometimes still be the better choice in the bigger cost/benefit picture, even if not from strictly thermal performance point of view.

Tiny may be true in the theoretical world but it's not tiny in the empiracle world. Regards.

The empirical testing of ICF vs. code-min stick built in the ORNL side-by-side residential study (also modeled using DOE-2 prior to construction) shows just how tiny it was in the bigger picture, even in a structure type & use better suited to take advantage of the mass than a school building. Reality tracks theory when you measure all of the relevant parameters. DOE-2 isn't perfect, but it's been well-validated in empirical testing, and not bad at all. (I'd take a DOE2 predicted number against any sale-droid number, no matter what kind o' sky-pie they're selling. :-) )

In a school building the extra R of a minimalist ICF even works against you sometimes from an energy use point of view. But being such a small part of the overall picture it doesn't hurt by much even at 2x the optimal R, whereas screwing up the glazing and roof by that large a factor would be a an energy-disaster for a high-performance envelope. Mass walls with the exterior skin only being EPS can be more readily optimized at the relatively low optimal R values of this kind of building.

Note that in that ASHRAE K-12 document, in zones 6 & up the recommended whole-wall R values are virtually identical for low mass construction & mass walls, and in lower zones the low mass wall recommendation is rarely more than ~50% over that of a mass wall.

Mind you, that's a generic set of recommendations by climate zone only- optimizing a particular design with energy use modeling for a particular site I'd expect it to diverge from those recommendations significantly & often, and it's better to trust the model more than a generic table.

My hats off to all the good work ORNL has completed. However, all that old study tells me is that if you ignore the roof and make the strong link (conventional walls) in a chain stronger (ICF wall upgrade) you shouldnt expect much improvement to the chain. Along these lines and to your point about roof design - I strongly discourage a BAT roof with ICF. That is to say a putting a screen door on a submarine ;) should be discouraged in this business.

For this reason I provided 25 ICF homes to the MIT study -(but only homes with spray foam attics). Unfortunately, I believe others may have contributed homes of the screen door variety (BAT attics). Regards.

Posted By Dana1 on 22 Dec 2011 01:40 PM
The empirical testing of ICF vs. code-min stick built in the ORNL side-by-side residential study (also modeled using DOE-2 prior to construction) shows just how tiny it was in the bigger picture, even in a structure type & use better suited to take advantage of the mass than a school building. Reality tracks theory when you measure all of the relevant parameters. DOE-2 isn't perfect, but it's been well-validated in empirical testing, and not bad at all. (I'd take a DOE2 predicted number against any sale-droid number, no matter what kind o' sky-pie they're selling. :-) )

Do you believe a properly designed and insulated wood frame construction can achieve just as good or higher R values over ICF?

For instance, a 2x6 wood frame construction, with 4"+ of closed spray foam insulation in the walls, 2" of EPS foam board on the exterior with a stucco finish. One can get R-30 or higher with the exterior walls?

Posted By Lbear on 22 Dec 2011 03:44 PM

Posted By Dana1 on 22 Dec 2011 01:40 PM
The empirical testing of ICF vs. code-min stick built in the ORNL side-by-side residential study (also modeled using DOE-2 prior to construction) shows just how tiny it was in the bigger picture, even in a structure type & use better suited to take advantage of the mass than a school building. Reality tracks theory when you measure all of the relevant parameters. DOE-2 isn't perfect, but it's been well-validated in empirical testing, and not bad at all. (I'd take a DOE2 predicted number against any sale-droid number, no matter what kind o' sky-pie they're selling. :-) )

Do you believe a properly designed and insulated wood frame construction can achieve just as good or higher R values over ICF?

For instance, a 2x6 wood frame construction, with 4"+ of closed spray foam insulation in the walls, 2" of EPS foam board on the exterior with a stucco finish. One can get R-30 or higher with the exterior walls?

In a 2x6 wood frame 16" o.c. with only 4" of closed cell suffers mightily from a roughly R4 thermal bridging for 20% surface area dedicated to framing. It might be ~R24 + R8(exterior) =R32 center cavity, but with thermal bridging that 2x6 wall RUINS the performance of that expensive R24 foam, yielding only ~R13 whole-wall(!)  for the studwall portion, to which you can add the  R8 EPS, for a whopping R21. (Or about a minimalist ICF) Plus, you only have R8 of thermal break over the band joists. 

A mid-density cellulose fill in the same 2x6 studwall yields R14 for a whole-wall number, since the thermal bridge of the studs in a fully filled cavity is ~ R5.5, not R4.  (The thermal bridging still sucks, but not as badly.)  As long as it's reasonably air tight it will edge out the cc foam @ 4" depth on thermal performance.

Moral of the story- save the foam budget for the exterior, use the cheap stuff in the stud bays.

Second moral of the story, always fill stud bays completely to maximize the R of the thermal bridge.

For less money than your R21 wall, you could flash-foam 1" of closed cell in the cavites for air sealing (or assemble the studwall using acoustic sealant between the plates & subfloors, and everywhere the sheathing meets the framing) the blow the stud bays with cellulose (or high density 1.8lbs Optima or 1.8lbs Spider,  or half-pound open cell foam) and skip the flash-foam. and the studwall portion comes in at ~ R15, to which you can add the sheathing-R.  With only 2" of EPS sheathing you'd get R22, but with 3" of iso you'd hit R32 (R31, derating the iso for US climate zones 6 & up), and it would be cheaper than the stackup you proposed.  

Alternatively (at an intermediate cost) you could dense-pack the cellulose/fiberglass in the stud bays and spray 2.5-3" of closed cell on the exterior (having pre-staged furring mounted on XPS-chunk standoffs for installing the siding) for a very high quality air-seal and hit a rock solid R30+. 

Whether that's cheaper than an R30 ICF depends a bit on the price of the concrete, labor, spray foam, and ICF forms in your area, but using spray foam primarily for air sealing and using blown fiber in the stud bays with exteior rigid foam is usually quite a bit cheaper than ICF. But it's not nearly as hurricane proof, isn't as quiet, etc.

To get much higher than R35 performance out of stick built w/ foam sheathing usually requires fatter walls or double-studs/Larsen truss complications, but it's a pretty standard way to build these days in cold climates. Siding replacements on existing stick-built in my neighborhood are typically adding 1" or more of rigid foam to the exterior. When you consider that a 2x4 fiber-insulated studwall has a whole wall R of ~R10, adding R5 in sheathing is a significant performance boost.

Bottom line, yes, properly designed and insulated wood frame construction can achieve just as good or higher R values as ICF- usually at lower cost.  There are plenty of good reasons to go with ICF, at R values under R30, even if bang/buck on raw thermal performance can't be rationalized.  If you skimp on window performance to stay within budget you would blow any climate-specific thermal mass advantage ICF would have over lower mass construction.  The mass advantage alone is pretty limited for ICF in most US climates.

Lbear, what exactly are you looking for? You keep asking the same questions. There is only one answer to the energy efficiency question. Yes, you can build a stick frame house and get higher R value than a conventional ICF house. But the magnitude of the difference is insignificant. In terms of monthly dollars saved on energy bills, the diff will not amount to a hill of sh*t.

Call some contractors, get some comparative pricing and make a freakin decision.

Dana - whole wall value of r4 studs with r24 in the cavity with 20% framing factor (which is a bit low for better homes) is 12.

R = 1/((.2/4)+(.8/24))

Granted it only a diff of 1. But in the other example how does filling the cavity change the r value of wood from 4 to 5.5?

Posted By Ray Gladstone on 22 Dec 2011 05:00 PM
Lbear, what exactly are you looking for? You keep asking the same questions. There is only one answer to the energy efficiency question. Yes, you can build a stick frame house and get higher R value than a conventional ICF house. But the magnitude of the difference is insignificant. In terms of monthly dollars saved on energy bills, the diff will not amount to a hill of sh*t.

Call some contractors, get some comparative pricing and make a freakin decision.

There's a thought!

The magnitude of the insulation & framing/structural costs can differ substantially when viewed on their own, but in the bigger picture it's not usually the cost driver of a home, particularly a high-end home (I've seen master-baths that cost more in fixtures & accoutrements than the insulation & framing package.)  There's no "payback" in energy terms for the thermal mass of  granite countertops or marble floors/staircases, even if it marginally improves the thermal performance of the building (do they give subsidies for that? )

And the R-value of the walls at R20+ is typically on par with (or less than) the impact of the window choices, and less than 1/4 the thermal performance of the house as a whole(!). Yes, high-R walls are a good thing, it makes the place more comfortable & energy efficient, but it's not the only thing.  On new construction it's almost a crime to build at less than R20 (whole-wall-R, not center cavity or mass-weighted R-equivalent), since the increase in comfort level over code-min at the climate's temperature extremes is "worth it" in most places, even if there isn't a net-present-value argument for it on heating & cooling savings.  It's far cheaper to build high-R than it is to retrofit high-R.  But what you're buying is comfort more so than near-term utility savings.

Codes are catching up- in many places IRC 2009 has been incorporated into code, and R13+5 (2 x 4 stick built, R5 sheathing, for a whole-wall R of ~ R15) is now code-minimum for US zones 5 & 6, and the cost of bumping that to 2x6 construction with R7.5 foam sheathing (R21.5-R22 whole-wall) isn't very much.  Code minimums make economic sense even for low cost cooling electricity & heating fuels on a 20 or 25 year net present value analysis.  When heating with oil or propane there's an economic rationale for code min x 1.5 or more (but with cheap fuels, maybe never.)  But the payoff in comfort is on the hottest & coldest day of year 1. 

At 2x code min there may be a 50 or 100 year  (or building-lifecycle) cost ationale, but at 2x code min you have to start looking at the lifecycle costs of (unsubsidized) photovoltaic panels and heat pumps, balanced against the energy savings of higher R. To go much higher would be to assume that in the future energy costs more than PV power supporting heating & cooling loads with an R410A-refrigerant air-source heat pump (like most mini-splits) costs RIGHT NOW!!

R30 walls would be about the max-rational for wall-R in US zone 5 where I live, and that's assuming a lower-cost method of achieving low-R (2x6 + 3" of exterior iso.)  An R20 ICF still beats my code-min by 33% (this is R13+ 5 country)  and is a perfectly fine way to go.  Going any fatter on wall R one would balance the benefit of a higher R wall against the energy returns/$  on a higher R roof/attic, or lower-U windows, etc.  The increase in creature comfort between R20 walls and R30 walls is barely noticeable, so a that point it's mostly about energy savings, and fatter EPS isn't always the best bang/buck on that front.