RE ALTON Shotcrete is Portland cement based which StuccoMax will normally stick to .

RE LBear How does one do the details to get any water that might get behind the wall to drain away and dry? StuccoMax is waterproof and after curing has created a permanent bond to EPS with no trapped water behind. As it cures, water is drawn to the exterior face towards air and allows moisture to hydrate outwards until fully cured. The only way water could be behind would be through surface damage through a crack which would also then allow it to escape. Trapped water usually occurs under acrylic/Portland cement based products which we are not.

So STUCCOMAX can be applied directly to the EPS on an ICF? YES

No chicken wire, no scratch coat? CORRECT, STUCCOMAX IS A ONE COAT THEN PAINTED.

Posted By ICFcoatings on 10 Oct 2012 07:36 PM
Dana, RE STUCCOMAX. StuccoMax does not contain any Portland Cement which is what the ASTM C 926, Standard Specification for Application of Portland Cement-Based Plaster relates to. StuccoMax is 100% waterproof meaning it has really no permeability at all. I would suggest you look at the following specs http://gigacrete.com/wp-content/uploads/2012/10/StuccoMax-Technical-Document.pdf

ASTM E96 (which is what I actually wrote, and not ASTM C 926 which I don't care about) measures water vapor permeance, which is absent from the specification you referenced.

Saying that by virtue of being 100% waterproof means it has no permeability is a context-free statement.  Even 10 mil polyethylene has a measurable vapor permeance despite being completely waterproof, as does 3" of closed cell polyurethane foam, which is also completely waterproof. 

If it's truly completely impermeable (similar to the permeance of say, 20 gauge stainless steel?) it's not appropriate to use on the exterior in heating dominated climates unless the R-value of the EPS is sufficient to avoid condensation issues within the fiber insulation on the interior studwall with only a class-III vapor retarder (such as standard latex paint) on the interior, and thus avoid mold issues in the wood & fiber.

Posted By Dana1 on 11 Oct 2012 06:51 PM

If it's truly completely impermeable (similar to the permeance of say, 20 gauge stainless steel?) it's not appropriate to use on the exterior in heating dominated climates unless the R-value of the EPS is sufficient to avoid condensation issues within the fiber insulation on the interior studwall with only a class-III vapor retarder (such as standard latex paint) on the interior, and thus avoid mold issues in the wood & fiber.

Would this apply to ICF?

Dana thanks for the info, we do know that StuccoMax is considered waterproof after testing with 5 foot water column test. Sto and Dryvit will not pass this 60” head pressure test.

Great info to help educate people on the materials out there.

Does StuccoMax require painting?  If not, then can color be added to StuccoMax before it is applied?  As you know, Sto and Dryvit premix can be purchased with color included.

Posted By Chris Johnson on 10 Oct 2012 07:30 AM
Based on how you described what this particular builder was doing, the simple answer is yes, ICF would be cost effective. Now keep in mind, as I see it the tipping point was the grout fill for him as not all areas require grout fill in the CMU.

In my area a CMU wall does not need to be core filled, this translates into about 28.5% straight 8" CMU vs. 6" ICF, typical 2x6 framing on the inside plus insulation is relatively inexpensive, and obviously not as effective as EPS. 1" EPS on the exterior is probably more labor costs than material and between the EPS and framing/insulation items would eat up the 28.5% savings.

The builder you spoke to may not be too familiar with ICF, ICF may not be popular in his area, there may not be qualified installers in his area.

Time wise the same amount of time was spent building the shell, CMU vs ICF install. The additional work of EPS exterior, Frame and Insulate on the interior should not effect the over build time as these items can be done when other work is being done on the project.

So many factors to consider, not enough background to figure out the real answer, perhaps you could go sell him for the next project!!??

Chris - in Calgary the cost of ICF is relatively the same as CMU. Stucco on the outside of ICF, nothing on the inside of either. Time frame for CMU is twice (man hours) the time for six month as four times the time for six months (hoarding takes time!!)

Posted By Lbear on 12 Oct 2012 03:55 AM

Posted By Dana1 on 11 Oct 2012 06:51 PM

If it's truly completely impermeable (similar to the permeance of say, 20 gauge stainless steel?) it's not appropriate to use on the exterior in heating dominated climates unless the R-value of the EPS is sufficient to avoid condensation issues within the fiber insulation on the interior studwall with only a class-III vapor retarder (such as standard latex paint) on the interior, and thus avoid mold issues in the wood & fiber.

Would this apply to ICF?

Depends on where any susceptible materials might be inside the assembly, but yes, there is some potential. The stackup under discussion here had fiber insulated wood studwall complicating the stackup. But many ICF buildings will  contain some structural wood penetrating the interior-side foam, but those at risk would primarily be in cold/very-cold climates.