Well I am planning to give this study to my ICF contractor for his opinion. I don't want voids or lower psi concrete by adding water. Good stuff thanks for shaving this information...

Use a very high flyash content. It vastly improves the flowability. Instead of just letting the forms fill up, watch where you place the mud and only vibrate when you lose track. We vibrated very, very little and I haven't found any voids.

There's are a lot of amateurish and unprofessional opinions being slung around here. In 2003, the Portland Cement Association did an in-depth study of concrete consolidation in ICF walls. It is considered by responsible ICF professionals to be the last word...

"Abstract: This report summarizes the findings of a study regarding concrete consolidation and the potential for
voids in insulating concrete form (ICF) walls. Eighty-four wall sections were constructed to represent a variety of
configurations including clear wall sections, corners, and lintels. Concrete was placed and consolidated using
internal vibration, external vibration, and by modifying the concrete flow (slump). Results of the study showed
that internal vibration could provide adequately consolidated concrete as long as proper vibrating techniques
were maintained." Here's a link to the full report
http://icfmag.com/documents/PCA_Consolidation_Report.pdf

It also says that high slump concrete worked. So is there general agreement with Lbear's "The belt and suspender approach is a good flowable mix (6" or greater) and the use of internal vibrators." {slump achieved with admixtures not extra water}?

As I read it, it also suggests that lack of consolidation in small voids right next to the rebar might not be detectable after the pour.

Good reason to skip the rebar and use Helix

Posted By smartwall on 25 Sep 2014 08:40 AM
Good reason to skip the rebar and use Helix

I was told that engineering code does NOT allow one to eliminate the rebar in all applications. Especially critical when tying the wall to the footing to create a continuity of tensile resistance and when using rebar to resist horizontal displacement, uplift and twisting forces. All of which rebar is necessary in and Helix cannot perform those functions.

The other issue I was told is that when it comes to inspections before the pour, rebar can be visually inspected while Helix cannot be inspected and poses liability issues.

I pour all my jobs mono pour, footing and wall in one shot. As far as Helix. Find an engineer that understands the product and they'll specify it every time.

I pour all my jobs mono pour, footing and wall in one shot.

It seems to me that someone should produce a jumbo block suitable for creating a fully (even underneath) insulated footing. Every design I've seen creates thermal bridging into the center of the wall.

Posted By smartwall on 26 Sep 2014 08:17 AM
I pour all my jobs mono pour, footing and wall in one shot. As far as Helix. Find an engineer that understands the product and they'll specify it every time.

How does that work with the local building inspector? Out here you can't do that. When you pour your footing the inspector has to come out to inspect it and once he OK's it, you can then do your stem/wall but the footing must be cured and inspected.

I feel so neglected. Polycrete Big Block is a "JUMBO" block. Our standard size ICF is 24" tall X 96" long. We make any core size from 5-5/8" to 24" full assembled. We make a footing form that's 1' tall, up to 36" wide and 8' long. Accomplished installers do a monolithic pour of walls and footing every day.

Do you have a link to a non thermal bridging footing design? - all I saw on the Polycrete web site were bridging designs.

We do put rebar in the footing but Helix for everything else. As far a thermal bridging, it was - 20 F last winter here in upstate NY, so being coupled to 55 degree ground is a good thing.

so being coupled to 55 degree ground is a good thing.

If your house it at 70F in the Winter, it's not a good thing - it's just not nearly as bad as some alternatives. Not to mention that footings just below frost level fall well below 55F.

@Jonr, sorry for the delay. Here's a link to great marked-up picture of a Polycrete wall on a Polycrete footing topped by a Polycrete Split-Blok. Most of our good pics are on our facebook page.
https://www.facebook.com/246132040589/photos/a.10152265429345590.1073741834.246132040589/10152265429515590/?type=3&theater

Posted By jonr on 26 Sep 2014 11:28 AM

It seems to me that someone should produce a jumbo block suitable for creating a fully (even underneath) insulated footing. Every design I've seen creates thermal bridging into the center of the wall.

Insulating under footings is a bad idea that can result in major structural failure of the home. The theory has been discussed by building professionals on Green Building Advisor and the consensus is that it's bad practice to try and insulate under footings. Some even question the long term structural effects of insulating slabs with rigid foam but for sure, insulating footings is a risky venture into the unknown on how it will play out 10+ years from now. We may start seeing major structural failures of foundations.

The tried and true method of placing a footing on raw natural, compacted, undisturbed soil works best. Termites and other critters can eat through foam, even borate treated foam. When the weight of your home is sitting on top of a foam board that can be damaged or literally removed, the footing can sink/shift which will result in major structural damage to the home. When the foam on the side of the home is damaged, nothing structural happens, since it's all just R-Value.

The minimal energy "gains" in having an insulated footing are not worth the cost and risk involved in putting foam under the footing. It's just a bad idea that doesn't have the time tested structural results.

There are many soils have have less bearing capacity than some foams. And are easier for insects to move. As Martin Holladay says on Green Building Advisor, "Yes, you can build your house on rigid foam — as long as you can convince your local code official to let you do it". There isn't any consensus otherwise.

Unheated type frost protected foundations have been built on foam for decades - and are still a recommended design. There are no mysteries regarding the structural properties of EPS foam.

Capillary barriers are a good idea

Yes, I also think the jury is still out with regard to insulated footings.

Helix is certainly getting more popular, but finding structural engineers that will design with it is still challenging. You still need to use rebar for ICF footing dowels and typically for door/window lintels too. Some folks have been experimenting with higher Helix density pours to avoid using rebar for the lintels. They add different color dyes to the mix to identify the different Helix densities for the inspector.  Personally, I think the jury is still out on Helix and I sure wish that we had better long-term data to see how well it holds up over time, especially in wet environments that may challenge its corrosion resistance and life.

And most everyone knows that you design your footings based on the load bearing characteristics of the soil…

Posted By sailawayrb on 29 Sep 2014 08:03 PM
Yes, I also think the jury is still out with regard to insulated footings.

Finding an engineer that will sign off and stamp his seal on a set of drawings that has rigid foam underneath the footing is next to impossible. Nobody wants to deal with the litigation/lawsuits when they fail and put their engineering license on the line. If one finds a structural engineer that will sign off on such a set of plans they will probably include footnotes that state the practice of placing foam under a footing is a new venture and there are undetermined risks involved. After that hurdle is crossed, the next hurdle is dealing with the local building inspector who will allow foam underneath the footing and sign-off on it.

Received my first shipment of Helix in Sept. 2006 and naturally we spilled some outside the loading dock.. It's been there ever since with rock salt hitting it every winter and except for lose of that new galvanized shine there is no rust. This isn't a scientific study but it proved something to me.