ICF or removable form construction?
Last Post 09 May 2009 08:39 PM by icfblocks. 10 Replies.
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wildblueUser is Offline
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02 May 2009 04:50 PM
I am working on my design for a concrete home. It will be about a 2200 sq ft single story ranch style with about half basement, half crawl space. The design will be simple with no odd angles that would require anything but straight forms. 

For the ceiling I plan on laying SIPs flat, covered with a typical wood truss roof.

I was going to use ICF due to its energy efficiency; however I’m now leaning toward cast in place with removable forms. When looking at the insulation factor, I had not realized that the foam board insulation can be placed INSIDE the forms and the concrete poured on either side so that it is not exposed and I can have a finished concrete wall on both sides.
 
A major factor is that there are many concrete contractors around here that are expert in removable forms and that have permanent crews and only a few small ICF contractors.

I believe the construction cost may actually be less with the form walls than ICF. I can hire one concrete contractor to pour the footings, basement floor, walls, main floor and to do the decorative work on the main floor. The guys I looked at use the latest form technology that goes up fast, not the old wood type.

In doing my research all I see is ICF compared to stick construction but not to removable form construction other than if you DIY with ICF you can save much.

Do you experienced folks have any input or suggestions for me? Are there advantages to ICF over temp form cast I am missing? Please feel free to shoot holes in my ideas. I’m not committed to anything except concrete construction. Why should I use ICF over removable form cast in place, insulated core construction?

As a side note, I’m also planning to use Krystol Internal Membrane (KIM) admixture in the basement wall concrete and floor, also their Waterstop system grout at basement footing/wall joints.
JetgraphicsUser is Offline
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02 May 2009 07:02 PM
Ah.... concrete + EPS + concrete = concrete sandwich!
Do the whole house in concrete sandwich walls, and laugh when the SHTF.
AltonUser is Offline
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02 May 2009 08:07 PM

Wildblue,

You might want to read up on the T-Mass system.  My biggest concern would be that the ties that hold the two concrete walls together would conduct too much energy (thermal path).  The T-Mass system uses non-conducting ties.  If the system you plan to use avoids thermal paths then go for it.  At least the exterior side of the concrete could just be painted without having to add exterior siding.  At least with the concrete + foam + concrete you can detect and repair voids in the concrete before the walls are covered.  I am still amazed at how many ICF installers do not vibrate concrete during placement.

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Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979
icfblocksUser is Offline
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02 May 2009 08:11 PM
My experience in the South East leads me to believe that the concrete "sandwich" style of construction is more costly than ICF.  It can be problematic to find an experienced ICF contractor but they are out there.  Contact some of the ICF companies and they may be able to steer you in the rite direction.  Unfortunately or fortunately the economy has driven many out of the building business.  Hopefully the competent have survived. 
Alton is correct in comment about vibration.  Lots of ICF construction is preformed without vibration.  In my opinion vibration is just part of a well done job.  Seen too many forensic investigations where little if any vibration took place. 
Thanks,<br>Tom<br>www.advbuildingtech.com
arkie6User is Offline
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03 May 2009 11:36 AM
How exactly do you intend to finish the interior and exterior side of the walls? On the interior walls, will you have different interior finishes on different walls? i.e. sheetrock on interior walls but painted concrete on exterior walls?

Where are you located and what kind of R value are you looking for the exterior walls? How much foam do you intend to put in the wall and what will be the overall width of the finished wall? Will you need to put steel reinforcement in the concrete on both sides of the foam? How will you attach windows and doors to this wall? Concrete anchors?
wildblueUser is Offline
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03 May 2009 01:12 PM
Posted By arkie6 on 05/03/2009 11:36 AM
How exactly do you intend to finish the interior and exterior side of the walls? On the interior walls, will you have different interior finishes on different walls? i.e. sheetrock on interior walls but painted concrete on exterior walls?

Where are you located and what kind of R value are you looking for the exterior walls? How much foam do you intend to put in the wall and what will be the overall width of the finished wall? Will you need to put steel reinforcement in the concrete on both sides of the foam? How will you attach windows and doors to this wall? Concrete anchors?[/quote]

Thanks for the questions. It is helpful to think about these things.
 
On the interior walls, will you have different interior finishes on different walls? i.e. sheetrock on interior walls<

Yes but probably little sheetrock.

How much foam do you intend to put in the wall and what will be the overall width of the finished wall?

I expect the finished wall to be 10" to 12" but I have not gotten that far. I am trying to decide if my idea is workable.
 
Exterior walls?

The south wall will be an attached solar heated green house for winter gardening. That's one reason I want exposed concrete on the exterior so I can use it as thermal mass in the greenhouse. I was thinking the rest of the exterior painted with a Nansulate coating or stucco with an insulating additive.

Maybe I'll do a hybrid house with that wall poured and the rest of the house ICF?

There will be steel reinforcement but I don't know how much. I need it to stand up to a mega-thrust earthquake. There is also fiber reinforcement that can be mixed in the concrete. Also I will use composite, not metal, connectors.

How will you attach windows and doors to this wall?
 
I don't know. There are options. It will depend on the contractors form system.

Where are you located and what kind of R value are you looking for the exterior walls?
 
Seattle area, mild winters and summers. Cooling will not be a big issue; we don't get enough sunny hot days to spend them indoors. LOL!
 
Heating with some type of heat pump or reverse chiller so I can have forced air and radiant floors.
jamesmacdonald1User is Offline
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05 May 2009 08:56 AM
Take a look at Durisol ICF. It might provide what you are looking for.
ICFconstructionUser is Offline
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05 May 2009 08:21 PM
T-mass is usually and should be cheaper than ICFs, it is inferior. The typical T-mass has less insulation and less strength. A two inch and and a four inch wall separated by insulation is not as strong as a six inch monolithic wall.

It is difficult to attach drywall and siding to a concrete wall such as T-mass. T-mass is the removable form industries way to keep using the pan forms and try to compete with ICFs, instead of setting them aside to rot somewhere (which is what they should do).
Brad Kvanbek - ICFconstruction.net
RobvUser is Offline
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05 May 2009 09:23 PM
The ICF systems I have used are getting better all the time. They have an R-40 rating and with the right help are cost effective to build with. There are a ton of accesories to help install features like window and door that add to the R-values as well. They have hardware for any application you could think of to attach to the concrete.The exterior veneer can be wood, stucco, or stone. The building is solid will not burn and sound proof if that is important. It may be if your out in the woods. For thermal walls pour cast in place with black concete, you can have it polished to add unique shine and add this to matching polished floors with hydronics for heat. If I was building in the North west I would build with the lowest energy footprint, lowest lifetime cost in mind.
Walls need to be poured with the right mix design to get to the correct PSI but the other advatage is the concrete is protected by the foam while it cures from extremes of hot and cold enviorments. The bracing systems and best practice make it so you can vibrate the walls no problem. There ae lot of simple tricks to insure that even the tricky areas get completly filled. The other practice is to look at the work and clean up any sloppy steel work or tranition in the work. There are good constructors in North West that will do the installation.
JetgraphicsUser is Offline
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06 May 2009 09:25 PM
Posted By icfblocks on 05/02/2009 8:11 PM
My experience in the South East leads me to believe that the concrete "sandwich" style of construction is more costly than ICF.  . 

What kind of sandwich?
[] shotcrete (i.e., tridipanel  http://beachshack.ai/1997-09-25.html)
[] tilt up (poured on site)
[] factory made
[] poured in vertical form

How much encapsulated insulation?
What kind of insulation?

Were there any form liners used to texture the exterior / interior concrete surface?
(i.e., http://www.dur-o-wal.com/Form_Liners.html?sc=326)

Frankly, initial costs are deceptive when evaluating functional shelter. In the long run, if you build something that costs more, but saves you $$$ on comfort, endures natural disasters, and won't burn, rot, feed vermin, grow mold, and can endure flying objects, I think it's a winner.

IMHO - it would appear that the least wasteful, frugal way to build a 'disaster resistant' domicile, would be to build a concrete sandwich wall, encapsulated insulation, and with textured finished surfaces. (and don't forget helix wire reinforcement http://www.helixfiber.com/ )


The next question: would removable vertical forms be better than tilt up panels?
icfblocksUser is Offline
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09 May 2009 08:39 PM
I was referring to poured in vertical form systems.  Usually with a foam core of 2" to 3".  The costs are a reflection of the engineering of the walls. I have seen jobs that were quoted using vertical forming sandwich systems and they were always more costly than ICF.  No form liners were mentioned in the quotes.  Walls were 10"

I think all of your listed benefits certainly apply to most types of concrete construction including ICF. 

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Frankly, initial costs are deceptive when evaluating functional shelter. In the long run, if you build something that costs more, but saves you $$$ on comfort, endures natural disasters, and won't burn, rot, feed vermin, grow mold, and can endure flying objects, I think it's a winner.

[/quote] [/quote]
Thanks,<br>Tom<br>www.advbuildingtech.com
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