ICF vs normal concrete block
Last Post 02 Nov 2009 05:42 AM by ICFconstruction. 28 Replies.
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cfl-greenUser is Offline
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30 Apr 2009 10:47 AM
Hi there,

I'm new to this and just starting doing some research on green building.
We are looking into building a larger home in the Central Florida (Orlando) area and would like to incorporate some green building aspects.

I've done lots of reading on ICFs but I usually only see them being compared to stick plans.
But how do they compare to "normal" concrete block construction which is usually used in Florida?

I'm interested to know what advantages to except vs using normal block in terms of strenght and insulation.
Can anyone give me a very rough idea what the price difference would be?
This is for a 2 story 2500sf downstairs, 1800sf upstairs.

Thanks!


jamesmacdonald1User is Offline
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01 May 2009 10:20 AM
From a thermal performance perspective, building a CMU wall and having 4" - 5" of insulation on the exterior would perform as well as (possibly better) than ICF. Strapping the interior and putting drywall would be the simplest interior finish. This may be less expensive than building with ICF (I have heard CMU gets installed for $2.00 - $3.00 per square foot including materials). With CMU option, you have the cost of CMU, insulation, interior surface prep (strapping, etc). With ICF there are no additional steps.

There is probably little difference on the non-structural performance.

With respect to structural strength. A reinforced concrete wall is typically stronger than a CMU wall with cores filled every X ft with rebar and grout. I am not sure whether this is sufficient reason to us ICF since both are designed to meet code requirements. Code designs are based on the 1/50 year wind loads or 1/100 year wind loads (I don't know exactly). An ICF wall might exceed these code requirements, but then again, you could grout fill every CMU core and be stronger than required by code as well.


DonnerwetterUser is Offline
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01 May 2009 11:39 AM
WOW!!!

$ 2.00 - $ 3.00 a square foot including materials??? Here in the USA??? Do these installers have Green Cards???


AltonUser is Offline
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01 May 2009 01:16 PM

Now why can't ICF walls be this low in price?



Residential Designer & Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu, 334 826-3979
DonnerwetterUser is Offline
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01 May 2009 02:25 PM

My installers have green cards and the gas station wants to be paid after I fill up the truck with gas...Go figure!


wesUser is Offline
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01 May 2009 04:12 PM
Lets see. A standard CMU is 8" tall by 16" long = 128 sq. inches divided by 144 = .888 sq. ft. of wall. That block costs me about $1.40, labor is $2.00, mortar, sand, etc. pushes the cost up to about $4.00 per block or about $4.50 per sq. foot. That is for empty blocks with no reinforcing steel, no grout, etc. Nothing that would make it safe to build more that 3 feet tall. Yes, you can build cheap walls with CMUs, but when you are done, you have a CHEAP wall.


Wes Shelby
Design Systems Group
Murray KY
wandr@ainweb.net
SoCalScottUser is Offline
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01 May 2009 06:19 PM
In Florida (South Florida) CMU has been mainstream for quite a while due to building codes in response to hurricane resistance, so the amount of residential walls built with CMU is much much higher than the rest of the country, therefore the subs are much more experienced and the installed rate is much cheaper - the same reason for the disparity between lumber framing and ICF. However $2 -$3 per s.f. is not quite accurate it is more in the $8 psf range (turnkey subcontract rate). This is still much lower than ICF installations wich can run between $14 and $20 psf depending on design. Granted, you still have to insulate the CMU wall. There are also upcharges for lintels in CMU walls.



JetgraphicsUser is Offline
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01 May 2009 06:45 PM
Don't forget dry stacked, surface bonded concrete block.
http://www.thenaturalhome.com/drystackblock.htm
http://www.acecreteproducts.com/products/surface_bonding.pdf
http://quikcrete.net/PDFs/Projects/MortarlessBlockConstructionWithQuikwall.pdf
http://www.ourmissourilife.com/2008/07/page/2/
http://mha-net.org/msb/docs/surfbond.PDF


Jim CUser is Offline
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02 May 2009 09:28 AM
The cmu wall here in central fl will be $6-8 per sq ft with rebar and lintels poured. Now add furring and insulation to the interior of the wall.

The cmu wall as typically done here in FL will be about R-13 This is very inferior to ICF

We typically use 6"core ICF which far superior to a typical block wall

I have found that typically a cmu house that requires 5tons of AC, the same house in ICF will be a max of 4ton.  This reduces the cost of installation by typically a min of $1400 now add this to the cost difference of cmu and ICF, along with the reduced energy bill.

If you are going to use hardie bd you will typically fur the ext of a cmu wall,  No need to on ICF which again affects the cost dif.

Don't frame your second floor!  Do it ICF

You can't simply compare the cost of cmu installation and ICF installation, there are many factors due to the individual home.

Attachment: misc2 001resize.jpg

cfl-greenUser is Offline
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02 May 2009 09:38 AM
Do we have to change the 2nd floor plan to match the downstairs bearing walls if we want to do upstairs walls in ICF as well?
What about Lite-Deck? Is this far more expensive than using a standard wood construction?


Jim CUser is Offline
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02 May 2009 03:05 PM

Any 2nd floor bearing wall will have to be supported properly regardless of construction.

Most of the time the exterior walls do align.



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02 May 2009 08:38 PM
Anything done in Florida must be engineered.  Most anything can be built with ICF.  It becomes a mater of cost.  When the question of "meeting code"  ICF will always exceed standard code requirements.  When you get near the coastal wind zones and need 130 mph requirements ICF, block, and stick will become equal in cost.  But the performance of ICF will still be superior. You can apply enough "doe" to block and stick built and get close but usually close only counts with horseshoes and hand grenades.

I have some pictures of block walls blown over during hurricane Charley that had grouted cores with re-bar.  I have never seen a picture of an ICF wall blown over in a hurricane, yet. 


Thanks,
Tom
www.advbuildingtech.com
jamesmacdonald1User is Offline
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04 May 2009 08:08 AM
I will backtrack and recant. My $2.00 - $3.00 per sq ft was based on information from a "tract" home builder and is about 12 - 18 months old. I am guessing they don't have green cards. Once you are at around $8.00 per sq ft for CMU, ICF will make more sense economically (or at least be a lot closer to warrant further analysis).


icfblocksUser is Offline
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04 May 2009 10:17 AM
If you add the cost of furring out the wall and adding insulation to equal the R-24 of the foam you have probably exceeded the 8.00 per sq. ft. cost of the block wall.  Now add the waterproofing qualities and safety to the air tight qualities of the ICF wall there is no comparison. Just the use of ICF will almost get you to a LEEDS qualified or Energy Wise Qualified building. 


Thanks,
Tom
www.advbuildingtech.com
arkie6User is Online
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06 May 2009 02:57 PM
Posted By schmausser on 04/30/2009 10:47 AM
Hi there,

I'm new to this and just starting doing some research on green building.
We are looking into building a larger home in the Central Florida (Orlando) area and would like to incorporate some green building aspects.

I've done lots of reading on ICFs but I usually only see them being compared to stick plans.
But how do they compare to "normal" concrete block construction which is usually used in Florida?

I'm interested to know what advantages to except vs using normal block in terms of strenght and insulation.
Can anyone give me a very rough idea what the price difference would be?
This is for a 2 story 2500sf downstairs, 1800sf upstairs.

Thanks!

The following link has some comparisons between an ICF poured wall and a comparable concrete block wall.

http://www.liteform.com/features.htm


ICFARXXUser is Offline
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06 May 2009 10:12 PM
Like most on here there is just no comparison. ICF is the way to go. By the time it is over the price will be fractional if you look at the big picture. One thing that has not been mentioned is the noise reduction and you are really creating about R 40 in the walls or better. That equals $. The over all feel of the house when complete and relaxing you will notice a big difference no kidding. I have installed many ICF systems all over the nation and the one thing that the homeowners and contractors say is that building with ICFs was the best decision they made in building there home.  


gncc35User is Offline
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26 Aug 2009 11:26 PM
arkie6 how do you figure an 8" unreinforced cmu is comparable to a reinforced 6" cavity icf. For starters to compare apples to apples you need to get the cmu on some type of equal playing field. If you either start them out with an equal outside dimension example 12" cmu vs 6" cavity 12" outside dimension icf or take the savings of the cost of the cmu and add reinforcing to the cmu and styrofoam for insulation and or both. also if you will notice lite form is using a psi of 1200 for cmu this is the minimum allowable psi to pass astm specification, yes a cmu has to pass stringent guidlines, but anyways if you were to ask the cmu supplier for the actual test results on their cmu you will find most will triple the 1200 psi listed in lite forms website.Now lets turn this around a little. Take a 12" cmu, reinforce it with rebar and core fill like icf has then apply 2" polyiso or polystyrene sheating to each side of the cmu and now you have a far superior product strength and energy savings. these icf companys have a way of wording things to trick the unknowing into purchasing their products it is very misleading and should be outlawed!!!!!


gncc35User is Offline
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26 Aug 2009 11:46 PM
This is the absolutely the most rediculous post i have yet to see on this forum, I think in earlier posts you have said that I have no idea what i am talking about, just look at what you just said, you are stating that a cmu wall is not safe to go over 3 feet high without reinforcing. You probably just started a pandemic!!! Now over 50% of the people in america are living in homes that are ready to collapse at any moment! Also if you check out some of the icf websites they have studies showing a 12" non reinforced cmu is equal in strength to a 6" reinforced icf , so now you would have to assume by your statement icf is not safe, also how strong would that icf be without any rebar. Why when everyone compares icf to strength of cmu do they always assume there is no reinforcing in the cmu. Everyone who has had any building experience knows what happend to concrete without reinforcing. Would you put trusses in a house without braces? Would you put roofing on a house without fasteners? Your comment yes you can build cheap walls with cmu is correct , then if you want to spend a little extra you can exceed the performance of icf , at leadt with cmu you have that option, with icf the strength is already mostly maxed out, but the cmu potential the sky is the limit!!!!


cking2User is Offline
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27 Aug 2009 08:39 AM
Posted By gncc35 on 08/26/2009 11:46 PM
This is the absolutely... but the cmu potential the sky is the limit!!!!


Oh god! Please, don't start answering your own posts now.


gncc35User is Offline
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27 Aug 2009 10:00 AM
that was your first post and that is all you have to say? That really answers alot of questions. If you want to go ahead and join the bashers and not add anything intelligent to the forum than go ahead but you will be the one junking it up for everyone who wants to come on here and get real facts!!!


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