Lbear
Veteran Member
Posts:2740
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| 09 Oct 2012 07:53 PM |
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I ran into a builder
who was working on a new residential build utilizing CMU & wood frame. I talked with him and he mentioned all the steps involved in CMU; the need to install 1" EPS
on the exterior of the CMU for the stucco wall, the need to furr the interior CMU walls with wood
frame 2x6s, and finally the need to still insulate the interior 2x6 wall cavities. This involved many different trades including masons. He also mentioned that he has to call in the concrete
truck a lot more times because with CMUs you are limited in pouring
heights. I believe he said 4' max. With all these different tradesmen, labor costs, time, wouldn't it have been cheaper to just do it with ICF?  |
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ICFHybrid
Veteran Member
Posts:3039
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| 10 Oct 2012 12:48 AM |
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With all these different tradesmen, labor costs, time, wouldn't it have been cheaper to just do it with ICF?
It is sorta hard to determine without knowing what was spent on the CMU, isn't it? |
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Lbear
Veteran Member
Posts:2740
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| 10 Oct 2012 12:55 AM |
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Posted By ICFHybrid on 10 Oct 2012 12:48 AM
With all these different tradesmen, labor costs, time, wouldn't it have been cheaper to just do it with ICF?
It is sorta hard to determine without knowing what was spent on the CMU, isn't it?
I'm speaking in general terms. With CMU you have numerous trades (masons, wood framers, insulation company) and the time & labor spent is much higher due to the numerous people & steps involved. I just don't see how it could be less money than ICF. |
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Chris Johnson
Advanced Member
Posts:877
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| 10 Oct 2012 07:30 AM |
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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!!?? |
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| Chris Johnson - Pro ICF<br>North of 49 |
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Lbear
Veteran Member
Posts:2740
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| 10 Oct 2012 07:33 AM |
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Here is an informative article from ICF MAG: ICF MAGThe author is our local GBT forum member, TexasICF. Well written article! |
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toddm
Veteran Member
Posts:1151
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| 10 Oct 2012 08:50 AM |
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Wow. Met a cmu builder. Read an article by TexasICF. What a coincidence. FWIW, in central pa, masons outnumber icf contractors 10-1. While both groups are very hungry, seeking out a ICF contractor signals that the odds are now down to 1 in 3. (Yup. Three of them.) Someone should explain economies of scale and learning curves to Cameron Ware. |
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ICFHybrid
Veteran Member
Posts:3039
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| 10 Oct 2012 08:52 AM |
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I just don't see how it could be less money than ICF. Is this another gedanken experiment in which you think real hard about something and come up with a concrete conclusion which then becomes gospel despite the lack of any methodological structure or data? Examples might be the universal superiority of a certain window or the absolute unsuitability of a particular building practice. |
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jonr
Senior Member
Posts:5341
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| 10 Oct 2012 09:45 AM |
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It's not clear to me why the 1" exterior EPS was needed. |
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Lbear
Veteran Member
Posts:2740
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| 10 Oct 2012 10:51 AM |
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Posted By jonr on 10 Oct 2012 09:45 AM
It's not clear to me why the 1" exterior EPS was needed.
It is used as backing for the stucco and provides above grade waterproofing. Every stucco home in AZ has EPS behind it. They usually use 1/2" - 1" of EPS, chicken wire and then the stucco coat. |
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Dana1
Senior Member
Posts:6991
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| 10 Oct 2012 10:59 AM |
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Stucco is often applied directly to CMU, but it's more apt to suck up moisture potentially compromising the interior 2x6 frame wall, and more likely to crack with foundation settling. Adding the inch of EPS enhances air tightness, puts a capillary break (and semi-permeable vapor retarder) between the stucco and brick, and allows a bit of mechanical compliance between the CMU & stucco to limit cracking potential.
Whether the EPS absolutely necessary is questionable, but it IS a more resiliant way to build with CMU, and brings the whole-wall R up to about ~R17, ( assuming ~R20 cavity insulation in the interior 2x6 frame wall.) |
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ICFcoatings
New Member
Posts:61
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| 10 Oct 2012 11:30 AM |
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If StuccoMax is used and applied to CMU it will not suck up moisture and will not Crack. It is an excellent choice for either CMU or ICF. FYI |
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jonr
Senior Member
Posts:5341
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| 10 Oct 2012 12:34 PM |
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I would consider putting the EPS on the inside. Perhaps drystack CMU or poured walls. |
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Dana1
Senior Member
Posts:6991
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| 10 Oct 2012 04:41 PM |
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Posted By ICFcoatings on 10 Oct 2012 11:30 AM
If StuccoMax is used and applied to CMU it will not suck up moisture and will not Crack. It is an excellent choice for either CMU or ICF. FYI
It's been referred to as "low permeance" in some of the promotional material, but there's no ASTM E96 rating in the specs. Putting it on the exterior of a building in a heating dominated climate without knowing it's permeance would not be prudent, if it's truly low-perm. |
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jacktca
Basic Member
Posts:180
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| 10 Oct 2012 05:24 PM |
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jonr wrote:
> It's not clear to me why the 1" exterior EPS was needed.
In Europe where it gets very cold styrofoam is applied to the outside. My mason told me he's from Pennsylvania, a cold climate, nobody ever applies styrofoam to the outside. It's an inside job. I had it all wrong. OK fine, read on..
> I would consider putting the EPS on the inside.
I was approached with the same situation by my mason. The foundation was ready for ICF's. He came across as knowing it all and I came across as stupid so I agreed. I caved in and built the structure out of CMU's with the plan to add styrofoam later. Biggest mistake in construction that I have made so far in my life! Interior walls need 16" on center rigid supports that you can attach drywall or plywood for tile backer board to. I cannot begin to tell you how much work I put into trying to install EPS on the inside. I ran out of space on the inside and did not want to frame it out with 2x4's. In the county I'm building you can build anything you want without permission or forgiveness. It has to be less than 120 sq. ft. I built an 8x10. Anyway, to make a long story short, EPS does not make sense on the inside. You would have to cut it up and dice it up to fit in 14.5" strips in between 2x4's. Better to just use fiberglass insulation. Take it from someone who has spent countless hours trying to get this to work: DON"T DO IT. Skull and crossbones!
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jonr
Senior Member
Posts:5341
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| 10 Oct 2012 05:47 PM |
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EPS ... cut it up and dice it up to fit in 14.5" strips in between 2x4's Agreed, I wouldn't do it that way. |
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Dana1
Senior Member
Posts:6991
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| 10 Oct 2012 06:23 PM |
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Posted By jonr on 10 Oct 2012 05:47 PM
EPS ... cut it up and dice it up to fit in 14.5" strips in between 2x4's
Agreed, I wouldn't do it that way.
No kidding! Better to put it flat against the CMU and put furring (or a 2x4 studwall) on the inside of the foam! With the thermal bridging of the 2x4s it takes the whole wall R value down about 25%, and without the foam between the wood and the (now weather-susceptible and moister) CMU the stud edges are at some risk of mold/rot. |
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ICFcoatings
New Member
Posts:61
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| 10 Oct 2012 07:36 PM |
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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 |
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Lbear
Veteran Member
Posts:2740
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| 10 Oct 2012 09:59 PM |
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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
How does one do the details to get any water that might get behind the wall to drain away and dry? So STUCCOMAX can be applied directly to the EPS on an ICF? No chicken wire, no scratch coat? |
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Alton
Veteran Member
Posts:2157
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| 10 Oct 2012 11:09 PM |
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Will STUCCOMAX bond to shotcrete? |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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Chris Johnson
Advanced Member
Posts:877
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| 11 Oct 2012 07:51 AM |
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Posted By Dana1 on 10 Oct 2012 06:23 PM
Posted By jonr on 10 Oct 2012 05:47 PM
EPS ... cut it up and dice it up to fit in 14.5" strips in between 2x4's
Agreed, I wouldn't do it that way.
No kidding! Better to put it flat against the CMU and put furring (or a 2x4 studwall) on the inside of the foam! With the thermal bridging of the 2x4s it takes the whole wall R value down about 25%, and without the foam between the wood and the (now weather-susceptible and moister) CMU the stud edges are at some risk of mold/rot.
There is actually a product out there used for retrofitting old non-insulated basement walls, comes 2.5 or 3.5" thick EPS, 4x8 sheets with 1x already embedded, just drill and tap con thru the wood into the concrete/CMU structure.
Some consider it expensive, but when you weigh in all the factors...not looking so bad after all |
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| Chris Johnson - Pro ICF<br>North of 49 |
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