Icf question

[BERSERKER8845]

Those of you that have icf experience I have a question for a 30x50 garage I'm going to be building. I'm in North Dakota I am going to use the Fab form footing bags that attach to the fox block icfs. The garage is going to be a full wall of icf (no stick framing). I'm just curious to see if the helix mix (steel wire) is sufficient for wall strength? I was thinking about using that with re bar or is that over kill? Or is just the helix added to the concrete enough for strength?

Sorry if this is a dumb question I have no experience with icfs

 

[matt_i]

Right or wrong, when I poured my footer I stubbed in pieces of vertical rebar, every 16". Then when I built the blocks I put in perimeter/horizontal bars every 16".

The manufacturer I used spec'd a pea gravel mix which says to me that they are having trouble with angular objects sticking in the forms and not filling completely. There is a lot going on in the corner ties. Helix wire (I saw some from the pump truck operator) I think would be way out there on the "difficult to fill" table of things you could put in the forms.

The cross-ties have plenty of "crack propagators" in the wall which exposed at the top (its a stem wall and not a full wall) but I don't worry knowing they'll always be tightly knitted.

 

[speed bump]

Taking a quick look through the application guide for helix I'm pretty sure you are going to be in the needs an engineers stamp applications unless you only want 10 ft walls.

You are still going to need to put rebar in the wall just not as much.

Personally with icf forms where I'm not spending a bunch of time tieing rebar and the rebar is needed to hold the forms together anyway I wouldn't be cutting back on the rebar. Blowing out a form on a wall form is catastrophic and dangerous.

Do you have a concrete provider or someone placing the walls who has experience with the helix material? Lots of really cool products on the market that only work well if you know how to use them. A 30x50 massive wall pour isn't where I would want to learn.

 

[GMCGarage]

Those of you that have icf experience I have a question for a 30x50 garage I'm going to be building. I'm in North Dakota I am going to use the Fab form footing bags that attach to the fox block icfs. The garage is going to be a full wall of icf (no stick framing). I'm just curious to see if the helix mix (steel wire) is sufficient for wall strength? I was thinking about using that with re bar or is that over kill? Or is just the helix added to the concrete enough for strength?

Sorry if this is a dumb question I have no experience with icfs

Fibers generally dont replace rebar in a concrete wall, they help with shrinkage, etc. The helix mix says it replaces rebar in a structural design, but it still needs to be designed. Seems it could get expensive too.
At 30' span for your area, I would make sure the walls are properly design for strength.

 

[anythingyoucanimagine]

I did a (small) slab addition on our house last year with icf and helix. Was a really cool process. Boom truck on street reaching over the house to pour. Was crazy. I did everything myself except the pour and the flatwork. The guys at helix and fab form were amazing. They really helped me/us out a ton. Most of why we needed stamps was about the interface of the new slab with the existing slab.


I don't know anything about doing walls. If you do slab on grade you can do it all in one pour. Anything with walls and you have to break it up. Speed bump seems like he's done it a time or two. Have you spoken to the guys at Helix?


The two hardest things I ran into was finding a concrete supplier who was willing to come do such a small job (with helix) and the ******* building inspector (he's family so I can talk **** about him .


But I also did stick framing on the slab.


Helix was very specific about exactly how much we needed, composition of the concrete, etc. Talk to them. They were really awesome. I'm pretty sure you don't need (traditional) rebar in a fab-form monopour system. Take a look at their web page. They have a few videos on their site and also tons of others on YouTube. You can probably look at several time-lapse videos and see that people don't use rebar in a traditional way with helix.

https://www.fab-form.com/fastfootMp/fastfootMpInstallation.php

Installation instructions in that link. Doesn't look like you need rebar at all.

 

[wssix99]

I am going to use the Fab form footing bags that attach to the fox block icfs.

I would not do this and would go back to conventional forms. One of the biggest life savers in the whole process is getting a clean, level footing. I would worry that the flexible formwork could move or settle during the cure and give an uneven surface. Even with a level surface, you will still need to take a LOT of time to perfectly level the first course. (See shims and glue below.) If you don't get the footing great, then your life will be H-E-L-L.

I'm just curious to see if the helix mix (steel wire) is sufficient for wall strength?

No. Fibers don't work the same in the same way as rebar. Fox will have a construction guide and you'll need to follow the specs, rebar sizing, and rebar spacing they provide in that guide.

The possibility exists to deviate, but as speed bump points out - that requires an engineer. (BTW - Finding an engineer that has ICF experience and has experience with your block type and is reasonably priced... is near impossible.)

The manufacturer I used spec'd a pea gravel mix which says to me that they are having trouble with angular objects sticking in the forms and not filling completely.

They spec pea gravel for pump-ability and ease of vibrating the mix into the voids of the block. The block can take angular aggregate just fine.

In addition to the metal fibers not working like the real-deal rebar, they will likely not perform well in the pump or vibrating in the block. (Again, it's only OK if Fox says it is and if they've calculated/tested it.)

We did 4 stories over 5 lifts and had the opportunity to play with the mix a bit. We were able to settle on a 3/4" chip aggregate which was a lot less expensive and worked just about as well as the pea gravel. (I personally prefer the chips over the smooth aggregate as I expect the aggregate interlocks and performs better. Full disclosure, we didn't perform testing but the concrete company had done testing to confirm their mix gave us the 3000 psi of compressive strength we needed.)

 

[MushCreek]

+1 on being sure that the footings are as perfect as you can get them. I built my house of ICF, and had a contractor do the footings and fill the forms. Stacking the forms was a breeze, and the whole structure come out extremely level, plum, and square without me having to do any compensating. I used rebar as directed by the manufacturer (Fox). I like to think all that rebar helps keep the forms from floating as they are filled.

 

[wssix99]

the whole structure come out extremely level, plum, and square without me having to do any compensating.

I think your experience in this regard is the only one I've ever heard of.

 

[MushCreek]

Checked with lasers, the top of two stories was within 1/4", which I consider very accurate for a house. The only adjustment was when filling the forms. They are set to lean inward very slightly, then adjusted once filled but not set. A string stretched tight from each corner is used to adjust to. I'm a toolmaker by trade, so I'm sure I spent a lot more time than typical to keep everything perfect as I went. But we also started with really, really good footings. I snapped lines, and glued the first course of blocks down with a foam gun. I was impressed by how accurately the Fox Blocks stacked up.

There was only one thing annoying about Fox. I used 8" for the basement, and 6" for the main floor. The two sizes, when fit together will line up on the inside, and leave a 2" ledge on the outside. That's fine if you want a brick ledge; I didn't. I had to shorten the blocks at the corners of the 8" to get the walls flush on the outside.

I did something unique with my windows. Due to the thick walls, you get a tunnel effect at the windows if you make them flush with the outside, and of course you need to make huge jamb extensions. Instead, I used windows for a typical 4" wall, and then tapered the forms on the inside. It makes the window seem much larger, and lets more light in. It was a fair amount of extra work, but I like the results. It would be cool if a manufacturer made special blocks for that purpose. Here's the semi-finished kitchen:

 

[Firebrick43]

As other stated, do a level footer first. Also I was interested in helix but decided against it.

One is that doing rebar is not that bad and it signicantly stiffens the forms up and holds them against the weather. I tied them well(not neccessary for final strength) as it helped even more.

Two was advice from my pumper. He actually liked helix from his point of view as it cleaned his pipes out of dried crusty bits and made cleanup easy. But he said it was rare for a load to come to him properly mixed. The batch plant has to carefully and slowly add it. He said most just chuck it in before heading to the sight hoping it will mix but because the wires interlock they stick in clumps. They are sharp so they won't stick their hands in(should use a hand weeder). He had even several times see them chuck the box, cardboard and all in. This was with multiple different yards not just one.

Also I would suggest something other than Fox such as logix, buildblock, or amvic. Every sight I visited that used fox had blowouts and bulges. My flat works guys couldn't believe the lack of and straightness of my walls.

 

[gnpenning]

I think your experience in this regard is the only one I've ever heard of.

All the icf installs including my own that I have been involved with other than dialing in the walls at the end of the pour, they have turned out flawless. Definitely far better dealing with today's lumber on stick framed walls.

 

[MushCreek]

It's interesting the different experiences that people have had. I have nothing but praise for Fox Blocks, and my walls came out perfect, but I'm meticulous in my preparation, and the crew that filled the forms had many, many ICF builds under their belts.

 

[imjustdave]

Checked with lasers, the top of two stories was within 1/4", which I consider very accurate for a house. The only adjustment was when filling the forms. They are set to lean inward very slightly, then adjusted once filled but not set. A string stretched tight from each corner is used to adjust to. I'm a toolmaker by trade, so I'm sure I spent a lot more time than typical to keep everything perfect as I went. But we also started with really, really good footings. I snapped lines, and glued the first course of blocks down with a foam gun. I was impressed by how accurately the Fox Blocks stacked up.

There was only one thing annoying about Fox. I used 8" for the basement, and 6" for the main floor. The two sizes, when fit together will line up on the inside, and leave a 2" ledge on the outside. That's fine if you want a brick ledge; I didn't. I had to shorten the blocks at the corners of the 8" to get the walls flush on the outside.

I did something unique with my windows. Due to the thick walls, you get a tunnel effect at the windows if you make them flush with the outside, and of course you need to make huge jamb extensions. Instead, I used windows for a typical 4" wall, and then tapered the forms on the inside. It makes the window seem much larger, and lets more light in. It was a fair amount of extra work, but I like the results. It would be cool if a manufacturer made special blocks for that purpose. Here's the semi-finished kitchen:

I like the tapered windows... but it reminds me of a prison windows... no experience inside just from seeing shows on TV. you should patent the idea .

 

[spudley]

I did something unique with my windows. Due to the thick walls, you get a tunnel effect at the windows if you make them flush with the outside, and of course you need to make huge jamb extensions. Instead, I used windows for a typical 4" wall, and then tapered the forms on the inside. It makes the window seem much larger, and lets more light in. It was a fair amount of extra work, but I like the results. It would be cool if a manufacturer made special blocks for that purpose. Here's the semi-finished kitchen:

That's a great look. Bravo.

 

[MushCreek]

I tried to get my contractor (who builds ICF) interested in the idea; even told him he could bring people through to see them. He said it would cost too much (Duh! Doesn't he know how to upsell?) I did have a guy I met through a forum come look at them, and he brought his contractor with him. Don't know if he did it or not. Some clever ICF manufacturer should make special pieces for that application. They also could be rounded and stuccoed, if that's your thing.