Puh leeze!! Unless you have some scientific evidence that earth coupling is possible in an ICF house, and anecdotal evidence from Colo does not qualify, then I'm with ORNL, which said in 2001 that the jury is still out on that particular claim. If you have some pull with the ICFA, TexasICF, then urge the board to put some money where your mouth is.

The MIT study compared ICF to code minimum houses and found them superior, or this blogger put it: http://www.treehugger.com/green-architecture/big-surprise-new-study-shows-insulated-concrete-forms-are-better-than-crap.html

The actual scientific part of the MIT study is its finding that the thermal mass benefit in ICF was worth 6 percent annual energy savings in Phoenix and 5 percent in Chicago. (Must not have connected the earth coupling plug, eh?)

Now there are many good reasons to build with ICF, as BrucePolycrete notes, and I would add building for multiple generations to his list. But energy savings is a minor one because you can get super tight and super R without pouring concrete.

OK, Narcszm, you own a thesaurus. Now work on your reading comprehension, come back and we'll talk.

Hey, if your client wants Durisol, use Durisol. IMHO the end product will be less strong and energy efficient than a monolithic concrete wall enclosed with EPS on the exterior and interior (standard ICF).
A house that breathes? Really?
Texas ICF refers to some colorado houses, probably mine. I live at 8,000' elevation.
Two houses, pretty much the same square footage, solar orientation, triple glazing, spray Urethene foam attic insulation. No formal study. But...
The SIP house easily drops 9 to 11 degrees (Fahrenheit) overnight during the winter. The NUDURA house loses only about 3˚F in three days.
The NUDURA walls have thermistors (?) cast in the concrete. An energy rater read these during his study of the house; average of 48˚F center of wall, 64" above floor level.
I'm convinced the insulated concrete is "wicking" low-grade thermal energy (isn't all energy thermal?) from the footers up into the walls.
I believe no air leakage, plus thermal mass really helps with the energy efficiency of a structure.
Best wishes for a happy Durisol house ( or whatever eventually is built).
FM

Todd,
"At which point you should ask what are you getting from concrete energy efficiency wise that spray polyurethane couldn't do for far less money? "
Where do you get "far less money"? And that wood wall will still mold, blow away, float away and burn well.

And narcszm is never wrong, just ask him. Cocky name for a newbie.

Interesting discussion. I enjoy hearing from both sides.

There needs to be a THIRD PARTY, independent study, apart from prejudice, bias, or monetary influence. The study needs to be scientific and give a thorough and definitive conclusion as to ICF construction and its benefits when it comes to energy savings. You have the ICF side claiming 70% reduction in energy costs, while a study shows 6% energy cost reductions. There is a great disconnect here. That study would finally put to rest any disputes.

I'm in the middle of doing energy modeling for a LEED project and that would be a good baseline for any comparison. It uses ASHRAE 90.1 2004 Appendix G. My next project is a Frank Lloyd Wright home which uses an 8" concrete block wall. I'll get back to the group with an eQuest decision. http://green-cincinnati.com/category/flw-boulter-house/

"ICF was worth 6 percent annual energy savings [over code minimum houses] in Phoenix and 5 percent in Chicago" that is ridiculous.

peterswet, the product seems to have its merit. If your client is committed to using Durisol, then it seems like it's somewhere right in between foam ICF and CMU, from a labor perspective, and it should perform much like other ICF. It may come down to surface finish and how your client intends to finish the interior and exterior walls.

BrucePolycrete points out that Durisol blocks stack mostly like CMU and have similar labor effort, maybe minus the grout work. The Durisol blocks are approximately 3.5 times the size of a 10" concrete block, and weigh about 30% less, so the production / block laying time should be about 1/4 - 1/5 the time of CMU construction. It's not clear whether the Durisol blocks need to be joined somehow (like an interlocking foam block), or simply aligned and braced.

I think the real difference from a construction and labor perspective between Durisol and foam block ICF is the first fix time of labor. Having to use a mechanical saw instead of a hot knife to make the cut outs for plumbing, electrical, and other utilities, is where building with Durisol would be much more akin to using CMU.

As for the side topic thermal discussion, Durisol should insulate much more effectively than a CMU. Durisol claims the thermal conductivity of their material is 0.083 W/m·K which, if true, is pretty amazing because it's only 4% higher than expanded polystyrene at 0.080 W/m·K, which is an order of magnitude less than CMU.

Posted By toddm on 18 Dec 2011 08:03 PM
Now there are many good reasons to build with ICF, as BrucePolycrete notes, and I would add building for multiple generations to his list. But energy savings is a minor one because you can get super tight and super R without pouring concrete.

That's a fair statement, and I agree there are many ways to skin the insulation cat. I'm unclear on what you're trying to offer or contribute by posting links that claim ICF is marginally more effective at a few things than other construction methods. Are you trying to dissuade peterswet from building with an ICF technology? Are you saying that Durisol may fare better or worse than other ICF solutions?
If your intent is to bash on ICF, that's probably beyond the scope of this discussion.

Back on the subject of Durisol, why would someone choose that over the more common ICF; can't be insulation or strength. It doesn't appear to be ease of use. If it is that it uses recycled wood, than why not a composite ICF like Apex or Cempo, they have recycled EPS and there is less use for recycled EPS than wood chips.

Posted By narcszm on 19 Dec 2011 02:00 AM
As for the side topic thermal discussion, Durisol should insulate much more effectively than a CMU. Durisol claims the thermal conductivity of their material is 0.083 W/m·K which, if true, is pretty amazing because it's only 4% higher than expanded polystyrene at 0.080 W/m·K, which is an order of magnitude less than CMU.

To answer the thread:  Someone early on suggested 2 inches of foam to the outside and I believe that's a good idea.  I think it was ICF Construction.  

Regarding the actual heat transfer claim ... It may be based on the foam inserts which actually add very little value.  Increasing the average R-value of the wall with the inserts may have helped get around code pre-IECC 2009 but that loophole is gone.  Anytime you have two materials in parallel to heat flow the path of least resistance is going to significantly dominate.  You may know this already but this equation comes from electrical engineering - two or more resistors in parallel.   Synergy is one thing but adding two conductors together (concrete and wood) is not going to give you the performance of an insulator.  I'll stop going on with this point but if you are interested in ICF -- its important to understand that this new code and old thermo is an important contributor to why the ICF market is growing today vs. CMU.   Regards.

Chuck, I read (and watched some of) your foam project and wondered if the webs of the blocks will conduct heat around the foamed cores. I am interested in your results. You should get the infrared camera lady back. My house design is a compilation of Usonian features. FLW knew how to design a small house, which is greenest of green in my view, in terms of energy and carbon footprint.

I missed the reason I would I have built with ICF were it DIYable: worry free stucco. Everyone has a unique set of circumstances and preferences and has the right to exercise them. BS claims are a different matter.

As one of the few that have tried both Durisol and other ICFs, and having developed a preference for Durisol, I will offer the following:

1. It is heavier than polystyrene, but lighter than CMU. In terms of overall build time it is a wash. Although the blocks are heavier, if you organize the site correctly and take into account the decreased bracing required for Durisol, it ends up being the same. We can typically install 13 - 18SF per manhour depending on the complexity of design/openings.

2. Someone commented/implied that the "hygroscopic" nature of Durisol is not particularly special or anything to get too excited about. The truth is that although wood does absorb moisture, when it does, it also is then prone to rotting and mold. Because the wood in Durisol mineralized and encased with cement, it is not prone to any of this. The water is technically "adsorbed" not "absorbed", which means the water molecules are stored in the large capillaries within the Durisol matrix and does not actually go into the wood particles. This allows the Durisol to buffer humidity without any cause for concern with respect to mold.

3. The other comment that humidity buffering is not relevent because we run AC to keep target RH is exactly the point of usingDurisol. Now you don't need to run the AC for temperature control (as a result of more energy efficient construction) and you don't need to run AC for humidity control since the Durisol will address this. With conventional ICFs, the humidiy issue is a big one and does necessitate the use of mechanical humidity control.

4. Although the R-value of the Durisol material itself is lower than polystyrene, the overall thermal units are the same or higher than polystyrene ICFs. With the rockwool inserts, you can get R-28 (true steady-state, 2-dimensional) not including dynamic effects. Some think that the webs are thermal bridges, but this is also not true. Durisol is R-1.75 per inch. With the 12" Durisol unit (R-21), the R-value through the cavity is R-21 and through the web it is 1.75 x 12" = R-22. Hence no thermal bridging/shorting. This is the same or higher than polysytrene ICF. Also, R-28 is available if you want even more R-value. The thermal bridging in Durisol is a red herring that does not reflect the facts.

5. You don't end up with less concrete with the higher R-value units. You do end up with a thicker wall. This might be an issue in some cases. At the most, you would get a wall that is 1" -2" thicker for the same R-value and same concrete core.

6. Saying that Durisol is "less strong" is also a bit misleading. Building codes require you to design and withstand the required loads with a required safety of factor. Providing something stronger might be better, but it costs more and is not doing the homeowner any favours. With Durisol, the same strength as conventional ICFs is acheived through a combination of more steel and less concrete. Conventional ICF will have more concrete and less steel. The whole point of codes and design standards are that we design to a certain safety factor, if you want more, you can get more with any ICF system and it will cost more.

Now, here are the true Pros and Cons (In my experience):

1. Pro - Can attach to Durisol at any point on the surface. the Pull out strength of Durisol material is 150lbs (50lbs with a safety factor of 3). This is better than cement/EPS material and EPS material alone. Not as good as the plastic webs, but more convenient and more than adequate for conventional building requirements

2. Pro - Can leave it exposed on the interior. Surface Burning characteristics are Class 1/A.

3. Pro - Impact resistant. Doesn't dent,break or chip. Stucco on Durisol is quite hard.

4. Pro - Hyrgroscopic (it really does make a difference).

5. Pro - concrete pours are easier. Because the Durisol is porous, air can escape through the face of the material. Voids in concrete occur when air gets trapped. With durisol, air can never get trapped.

6. Cons - Need an air barrier. This is like conventional construction, but better. conventional ICF has naturally better built-in air barrier than Durisol

7. Con - Blocks are heavier. The installers used to polystyrene will complain.

Environmental considerations are there, but some people care and other don't, so I won't get into them.

Anyway, I think if you look at it from a technical/logical point of view, there is a lot of merit to the system. Like anything, there is no perfect system and you need to evaluate the system against your own prioritized goals and then make the decision. Using Durisol won't ever be the wrong decision, just like using SIPs or polystyrene.

Hi Todd, Regarding your question about pumping insulating foam into the concrete block cavities of our 1956 Frank Lloyd Wright home, I'll need to research how to model the concrete webs that still act like thermal bridges. Roughly, I'll start by modeling 92% of the walls as having layers of concrete, foam and concrete. And model the other 8% of the concrete block wall as solid concrete. I'm using DOE-2 eQuest and that is how they look at thermal masses. It's all about the timed transfer of heat through the thermal mass in the modeling process. Thanks for the question. Learn more at http://green-cincinnati.com/category/flw-boulter-house/. I'll post the savings after I get a comparative heating bill.

i can add two more cons, based on my experience with AAC and cautioned by the fact that I have never laid eyes on a Durisol block:

Durisol was considerably more expensive than AAC when i shopped hybrids a couple years ago. Shipping is a major issue for composite ICFs, though, and NS should be closer.

Don't listen to folks who tell you dry stacking blocks is idiot proof. Aercon, my block manufacturer, promises a sixteenth inch tolerance in the mating dimension. But up by four courses, that tolerance can turn into a quarter-inch problem. Above all, you need a perfect start on the first course. If you can't find an experienced Durisol installer, and the house is reasonably complicated, I'd definitely scout up a mason with a sense of adventure. My house wouldn't have gotten done without John Sucik, mason extraordinaire.

Nothing is really idiot proof (idiots can do a lot of damage when they are left to their own devices). The quality and speed of the build is directly related to the quality of the installer. Durisol won't make a bad installer do a good job and it won't make a good installer do a bad job.

James, good info. I am still sceptical, but that is never having worked with it, but would like to. I heard the material cost is about $7 sf, that is more than double what I pay for the typical ICF. Is that accurate? How about Faswall? I have heard they are better made?

At the risk of continuing to sideline this post (sorry OP), I'm gonna throw my hat in the pile.  My neighbor across the street from the ICF house we building was curious about the energy savings as he had never heard of this type of construction.  His home is slightly bigger (about 5% more sq ft), both with walk-out basements and very similar hvac setups (radiant, etc).  After realizing we are both in the same industry (data center power and cooling OEMs) we decided to compare utility bills when all is said and done.  I know it won't be a perfect comparison and far from scientific, but it will be real-world and honest.  His is 2x6 framed with spray foam, should be interesting.

Posted By mike597 on 20 Dec 2011 06:48 PM
  I know it won't be a perfect comparison and far from scientific, but it will be real-world and honest.  His is 2x6 framed with spray foam, should be interesting.

Here's hoping you don't have a conventional roof and attic insulation. Start a new thread and keep us up-to-date; many will be interested in your method and results.

Posted By narcszm on 20 Dec 2011 06:55 PM

Posted By mike597 on 20 Dec 2011 06:48 PM
  I know it won't be a perfect comparison and far from scientific, but it will be real-world and honest.  His is 2x6 framed with spray foam, should be interesting.

Here's hoping you don't have a conventional roof and attic insulation. Start a new thread and keep us up-to-date; many will be interested in your method and results.

I'm waiting on 2 estimates from insulation contractors but right now it looks like spray foam for the attic.  I might have missed something earlier in the thread but what do you mean by conventional roof?

Conventional roofs typically have little or no insulation between the underlayment and sheathing, and no insulation in the attic rafters (inside the sheathing). Conventional attics are typically vented with passive inlets in the eaves with a ridge vent, so air turnover in the attic is fairly high. Having a rigid foam near the sheathing with a small air gap for ventilation might be the best you can do in your climate. If you can get away with a sealed attic, you're doing even better. Expanding spray foam (which I presume you're installing between the ceiling joists) should also provide very good performance.