lzerarc
Basic Member
Posts:423
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| 06 Jan 2011 09:59 AM |
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I've been researching pros, cons, facts, myths, case studies, you name it for countless construction systems. I have ICF quotes, ICF block quotes, SIPs quotes from urethanes, eps cores, and also framing numbers for various wall types.
Living in Iowa, our climate is cold, but also hot and humid during the summer. I can basically DIY using Hobbs ICF my upper floor for around $8k including block and concrete. Basement will already be Hobbs ICF. It would be continuous from footing to roof, with the floor framing suspended from the walls. garage frost walls would also be ICF.
Looking at their numbers and case studies, it gives a much different true result of what is often claimed by pushers and sellers of ICF. Case studies I have read are showing ICF perform very well in warmer climates, and not as well in colder ones. Basically an r-20 ICF around here was shown to only benefit from the "mass" (insulated mass, so I so not buy the claimed benefits) by pushing it up another r2-4 with total r around 24-28 for the Hobbs system. Obviously infiltration is next to eliminated completely , but it also is in the other methods I am researching as well.
When compared to a similar price of 6" urethane core SIPs of r-40, it seems to me the super high r for my area would be far more efficient then an ICF wall.
Another thing that concerns me is the construction of each. I am very confident I can do the SIPs and the framed option is also easy. While the block and pouring isnt the main issue, is the finishing out that I am thinking of. Tieing in the inteior framing. Do people usually use the simpson ICF clips? in which case EXACT placement of interior walls would need to be set prior to pouring. I have also seen details of removing some foam and using concrete anchors or tapcons directly to it, but why would I want to remove foam from an already low r assembly?
Also things like cabinet attachment. the L shape kitchen shares an exterior wall. I have also seen details of cabinets being installed again using the simpson icf clips. certainly the plastic screw flanges cant hold upper cabs can they?
What about changes or additions down the road? I was working on my parent's addition and we had the entire thing framed up, roof on, etc. My mother decided she wanted another window added over a staircase.
We ordered the window, i got out the circular saw and cut through the sheathing and reframed it. no big deal.
these are all things I am considering. At this point, it does not really rely on cost, as they are all around the same amount with ICF and SIPs. THe framing is as expensive as I make it. Right now, it is about 3-4k (materials) less then SIPs or ICF option. (again, materials).
ICF seems like a great strong system, but there certainly seems like a bunch of possible issues and not so easily correctable mistakes. |
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thagreen
Basic Member
Posts:283
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| 06 Jan 2011 10:33 AM |
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First off when looking at R's look at the performance and not the value. Regular framing performs at half it's value and icf's add almost 10 points to performance because lack of infiltration.Search this site there's a ton of treads on this issue. My climate is also hot and humid and cold .The icf I've installed for my up to rafters home has an
R- PERFORMANCE of 36. You are right about the fact that choices for windows must be determined and consequently approved before concrete is poured. However in a case where a window addition is required a few years later or sooner, steps to creating this opening will not be any more difficult or time conssuming than another building system. It's only a matter of using different tools to accomplish the end result.
Looking at your post, whichever structural system you choose is considered efficient so congratulation on taking the initiative to create a better living environment for yourself. |
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dmaceld
Veteran Member
Posts:1465
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| 06 Jan 2011 10:41 AM |
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Posted By lzerarc on 06 Jan 2011 09:59 AM
Tieing in the inteior framing. Do people usually use the simpson ICF clips?
Also things like cabinet attachment. the L shape kitchen shares an exterior wall. I have also seen details of cabinets being installed again using the simpson icf clips. certainly the plastic screw flanges cant hold upper cabs can they?
What about changes or additions down the road?
I found the Red Head drop in anchors worked great. Drill into the concrete, set the anchor, and use a 3/8" bolt of whatever length is needed to go through the stud and foam and into the anchor. Very solid. I hung cabinets with screws into the webs. With a web every 6" you can put in lots of screws. The Red Head anchors would also work. Changes? Ever heard the phrase, "Set in concrete?"  |
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| Even a retired engineer can build a house successfully w/ GBT help! |
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lzerarc
Basic Member
Posts:423
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| 06 Jan 2011 10:53 AM |
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I understand differences between wall r and performance r. I am trying my best to compare apples to apples with performance. All systems will be very well sealed and should maintain very similar infiltration rates. The frame wall would be 2x6 advanced framing, plates caulked, with zip sheathing, then 2" of XPS. The idea would be 2 layers of 1" offsetting the seams. it would also be able to be ran past the rim boards creating a full seal from ICF foundation to roof. This should give me around an r-32 and very tight. dm- I am trying to avoid drilling into the concrete...i hate drilling into concrete loud, takes time....would rather just shoot a nail gun.  Technically, there are only 2.5 wall cabinets on the exterior wall (.5 is due to a corner unit) so its really not as bad as I make it out to sound, ha. |
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Alton
Veteran Member
Posts:2164
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| 06 Jan 2011 12:50 PM |
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Izerarc, Since you will be building in Iowa, have you priced out the Thermomass system? See http://www.thermomass.com/ . I have been getting quick respones from E-mails with Linda Conaway of Thermomass in Boone, Iowa. I wish other companies would respond as qucikly. |
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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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lzerarc
Basic Member
Posts:423
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| 06 Jan 2011 02:13 PM |
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they have came and gave lunch n learn presentations at my firm before, but I do not think we have spec'd them for anything yet. its really more geared toward a cast in place, non-ICF style application of I remember correctly. Simply breaking the concrete and holding the wall together by the ties. |
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Alton
Veteran Member
Posts:2164
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| 06 Jan 2011 04:29 PM |
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It is non-ICF style since the foam is inside the wall. I understand that Thermomass lends itself to cast-in-place, tilt-up on job site and factory precast. |
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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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mslgaltx
New Member
Posts:8
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| 06 Jan 2011 09:58 PM |
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Izerarc,
You may look at air entrained concrete, it has an R value of 3.9 or so per inch, Google will bring up some of the research articles on it. I was considering SIPS myself until I read about how easily they transmit sound.
Scott |
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TexasICF
Advanced Member
Posts:622
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| 06 Jan 2011 10:19 PM |
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mslgaltx, I agree with you regarding the STC for some SIPs if they transmit sound they may have an infrastructure that transmit heat via steel or wood. I am, however, very curious about the air entrained concrete r-value you mention above. I found it on Wiki but would appreciate you pointing me to some of the other articles you mentioned. Air obviously has an r value as does concrete but is is hard to imagine (for me) that mixing the two can have an R-value so much higher than each - or the sum of its parts. Regards. |
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dbollermann
New Member
Posts:20
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| 07 Jan 2011 10:12 PM |
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I'm not sure if air entrained concrete is the same thing as the autoclaved aerated concrete blocks that were somewhat popular a few years back. Those blocks boasted a high r-value and were reputed to be easy to finish with stucco or plaster. They required that hollow cored blocks be placed vertically and horizontally at even intervals and around openings, with these "columns" and "beams" being filled with rebar and concrete. This created a post and beam structure with aerated concrete infill, not unlike a post and beam wall with straw bale infill. A builder friend of mine built one building with them and didn't want to do it again. His comments were that they were hard to cut and stack straight (he's a precision kind of guy), no place to run plumbing and electrical, etc. There are lots of ways to build, but for what it's worth, everyone I know that has built with ICFs loves them. Advanced framing with spray foam and or SIPS may have their places but everyone I see doing those things wanted to build with ICFs but thought they could get close to the quality of an ICF structure, especially when measured on one metric, like r-value, for a few less bucks. They may have done that, time will tell, but I don't hear any of them raving about their buildings like the ones who went with ICFs. If you have the opportunity; I suggest you tour a few buildings being built or recently built with the systems you are considering. My experience is that the inside of an ICF building has a whole different feel than any framed or SIPS building that I've ever been in. It's kind of like being in a man made cave or bomb shelter, it just feels solid and secure. It's a subjective thing. Yes ICFs cost a little more up front. Thermal performance wise, with the exception of houses built with some of the very early type cementious ICFs, I've never seen anyone in this climate with zero degree and below winters and 100 degree and above summers that wasn't more than happy with the thermal performance of their ICF house. Yes, you can probably get the same thermal performance from other systems at a similar cost, and maybe get the same MPG from a Ford as a Mercedes. The question is, what do you like?
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galore
New Member
Posts:40
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| 08 Jan 2011 09:42 AM |
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SIPS being wood is too susceptible to degradation over time for my taste. With ICF, the thermal performance and air infiltration won't change and it's solid. |
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slenzen
Basic Member
Posts:434
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| 08 Jan 2011 10:34 AM |
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Posted By Alton on 06 Jan 2011 12:50 PM
Izerarc,
Since you will be building in Iowa, have you priced out the Thermomass system? See http://www.thermomass.com/ . I have been getting quick respones from E-mails with Linda Conaway of Thermomass in Boone, Iowa. I wish other companies would respond as qucikly.
what kind of R value are they getting from thermomass now? It seemed the insulation was fairly minimal 1-2" ? Wonder about cost vs. other systems as well. I inquired at a builders show years ago and they said it was pretty expensive, but things may have changed over the past few years. I did tour the builders show home in orlando that was built with thermomass. Western Forms has a concrete insualtion system as well. http://www.westernforms.com/Systems...fault.aspx |
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Alton
Veteran Member
Posts:2164
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| 08 Jan 2011 11:55 AM |
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Slenzen,
My understanding from communicating with Thermomass (Linda Conaway) and an Thermomass installer in Atlanta, GA (Doug Herbert) is that the thickness of insulation can range from 2" to 8" between the two wythes of concrete. By using brand name Styrofoam the R-value would range from R-10 to R-40. I also understand that most applications use 2" of Styrofoam. |
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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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buildbetter
New Member
Posts:3
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| 08 Jan 2011 04:39 PM |
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Instead or R value's look at U value's as they are way more accurate. Also look at M.I.T's study of icf's, you can't go wrong. |
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TexasICF
Advanced Member
Posts:622
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| 08 Jan 2011 06:11 PM |
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Buildbetter, I have to agree with you that U values are better. Most don't know why. You may likely know this already but it's not as straighforward as most think. So, here's a tidbit that might be valuable:
Using R-values:
What's the R-value of the following wall: 16" O.C. 2x6" (Wood R-value of 1 per inch) and filled with foam (Foam R-4 per inch)?
1) Many builders will say it's an R-24 based on 6"x R-4 per inch.
2) Another builder will say since your typical 2x6" is actually 1.5x5.5" the R-value is 5.5 (R-4 per inch) or R-22.
3) Still another builder wanting to be more accurate will acknowledge the stud contribution and calculate an average:
In my example, I'm using a framing factor of 20% (some will argue that it should be lower based on the 16" O.C.) but ORNL and others say that due to headers, top and bottom plates etc. the framing factor it is often as high as 25%. The framing factor represents what percentage of the envolope has the R-value of wood.
Therefore; 20%(5.5) + 80%(22) = R-18.7
So which is correct? R-24, R-22, or R-18.7 ?
Actually all three of these calculations are mathematically correct but each used the wrong formulae.
Using U-values:
The U-value is 1/R-value. Therefore:
U-value of wood in this example is 1/5.5 and U-value of foam in this example is 1/22
The R-value of the wall = 1 / ((%wood)*(U-value wood) + (%foam)*(U-value foam))
= 1/ ((%wood)*(1/R-value wood) + (%foam)*(1/R-value foam))
= 1 / ((0.2)x(1/5.5) + (0.8)x(1/22)) = R-13.75
If you want to build conventionally and exceed your typical ICF you will need to build with a 2x10" filled with foam (with no air infiltration). Then you will have a similar R-value, much lower STC, much lower fire rating and you will still be significantly weaker (perhaps 4-5x) than ICF.
If you question my equation I suggest you try two things:
(1) Replace the studs with 20% NUDURA at R-22 and the foam with 80% ARXX at R-22 - if you get a resultant R-22 then you know you have the equation correct.
(2) Leave the studs in the assembly and introduce extremely high make believe R-values in the foam e.g. 100, or 1,000.
Why do the numbers change very little in terms of the resulting R-value of the wall assembly?
When you have a small resistor (studs) in parallel with a large resistor (foam) adding more foam (or making the large resistor larger) doesn't help. Regards.
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lzerarc
Basic Member
Posts:423
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| 09 Jan 2011 10:53 AM |
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thermal breaks play a huge role in that equation as well.
I started adding up additional items I would need besides the block and concrete. Adding in the rebar (about $400- Hobbs requires vertical every 16" and cont. horizontal at top and bottom)
but the kicker is the Simpson ICFw acnhors to suspend the LVL within the ICF. In addition, you need to add a cont. LVL the length of the house x2, and then the work and expense of hangers every 16" oc for the floor structure. The ICF anchors are not cheap either. They added around 500, LVL would be around 600, plus anoth couple hundred for hangers and nails. Basically we are adding another 1500-2000 to the price of the block (6k) and then concrete (2k) plus pump (900).
Comparitively, a double stud wall with ZIP exterior sheathing, and an r-40 prices out around 4k including cellulose. Again, all prices are DIY.
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galore
New Member
Posts:40
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| 09 Jan 2011 05:48 PM |
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Going through a DIY build myself (concrete with external EPS insulation; poured in place - not ICF) I find it awkward that you nickel and dime the shell construction. +/- $2000 is NOTHING in home construction; this may matter to high volume builders where $2000 or each home adds up to $2M for 1000 homes but for DIY there are so many variables that are difficult to control that worrying about a $400 price for rebar seems a bit weird. I'm DIYing because I love manual labor and construction and because I could not afford otherwise and I do have to keep a tight budget but deciding on what system to use based on a $2000 difference seems weird (I mean this is probable less than 2 months mortgage payment; why would this amount be so significant to decide on the bones of the house???) |
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thump
New Member
Posts:14
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| 09 Jan 2011 06:09 PM |
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Thank you Galore for breathing some common sense into this thread. |
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lzerarc
Basic Member
Posts:423
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| 09 Jan 2011 10:24 PM |
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its not a 2k difference, I was simply pointing 2k additional items required besides the already 7k higher, so its more of a 9k difference. the point of DIY is to manage the budget and make a build possible that otherwise would not be. It would be different if I were comparing a bad system (2x4 framing, batts and sheating) to something like icf or sips. but i am comparing r35-40 construction with icf/sips construction, attempting to justify another 9k to the budget over wod framed materials.
we are still waiting on the rest of the final numbers from subs and bank funding to be finalized, and if we can swing the additional, then I will most likely opt to go all icf, or maybe icf and sips upper. |
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slenzen
Basic Member
Posts:434
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| 11 Jan 2011 09:53 PM |
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Posted By Alton on 08 Jan 2011 11:55 AM
Slenzen,
My understanding from communicating with Thermomass (Linda Conaway) and an Thermomass installer in Atlanta, GA (Doug Herbert) is that the thickness of insulation can range from 2" to 8" between the two wythes of concrete. By using brand name Styrofoam the R-value would range from R-10 to R-40. I also understand that most applications use 2" of Styrofoam.
thanks Alton, I didn't know they could range up to 8" of foam. |
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