Hi all!

I'm a homeowner who is planning to build with ICFs (I should say LANDowner... there's no home on it yet ). I've no experience whatsoever with ICFs, but I've been doing a lot of research. GBT has been a GREAT resource for that! Mostly, I've been able to find answers to my questions, but I had a few ones on concrete placement that I could not find answers to.

So the home is going to be 2-story with a basement and an attic. That means approximately 8.5 feet x 3 stories = 25.5 feet of wall height. I'm also thinking about making the gables ICF as well, so that would add even more height.

1) Is something like this doable in 1 pour? The walls will be 6".

2) If it's not doable in 1 pour, how many pours should I aim for?

3) How long should I let the concrete cure between pours?

4) Is there a particular point in the wall that would be better for me to stop at? Maybe I'm phrasing the question wrong, but where do I want the joint between the pours to be: in the middle of the wall, near the bottom of the wall, near the top of the wall?

I'm sorry if these questions have been answered here before, but I've not seen anything that addresses a situation exactly like this one, and I really don't want to mess this up!

Tall walls can be done they require a really top notch icf contractor as well as some very specialized equipment. I would stick to the standard pour for each floor. As far as the time between lifts, it depends on your mix and the weather at the time of the pour. I usually pour a 3 slump with a mid range water reducer this sets the concrete faster because you have taken some of the water out and the water reducer falls out of solution after about 45 minutes, so you go back to a 3 slump.

Well Ill take a run Concrete achieves near full strength at 28 days. This time can usually be shortened to continue construction, but that will depend on your local conditions. You will have to wait this time for the wall to strengthen sufficiently to support the weight of floor systems and each sucessive wall section. Each pour is one floor. This is done in 20"-30" lifts to allow for consolidation with a pencil vibrator and to keep the hydraulic pressure of the still liquid concrete from blowing out a hole in the ICF. You need to install the floor/ceiling systems at the top of each wall section to provide the support for the wall below before you can proceed upward with the next wall section. You also need the floor system to install the bracing and scaffolding for the next wall section above the floor.  Without the floor systems installed, as mentioned a lot of additional specialized equipment and expertise is required to skip the smaller pours and deal with the taller "fluid" wall.  As I see it you will have the following typical pours for your tall house:
1. Foundation/footings.
2. Basement wall to about 8" above main floor system(halfway up next course of ICF blocks?).
3. Basement pad(then install main floor system and backfill).
4. Main wall to just above next floor system(then install second floor system).
5. Second floor wall(then install attic floor system).
6. Gable ends(then install roof).
With such a tall and heavy wall, and depending on how much of the basement is below grade and your soil type of course, the basement wall may need to be thicker(8" or 10") to support the wall above and retain the backfill without distorting.

Want to get a visual idea of what this looks like, search ICF pouring and construction on youtube. Lots of interesting construction videos there to help you get your brain around the issues...

I like to combine steps 1 and 2 and in the right situation 1,2 and 3 can be done in one pour

I believe 48" lifts are pretty typical for most ICF systems these days. TFSystems has stated that you can do full 12' lifts with their newest vertical ICF product and consolidation via vibration isn't required with proper Helix mix. The forms certainly look robust enough, but not sure I would be brave enough to try it. The pouring sequence largely depends on design (basement, slab-on-grade, or above-ground slab) and if you placing tube for hydronic heating. For typical non-basement construction, one would pour the footings and wait (or perhaps pour footings/slab at same time if slab-on-grade), pour the ICF walls and wait, and then pour slab.  For basement construction, what others indicated.

Thanks for the responses! It definitely helps make things clearer...

ron: Yikes, 28 days between pours sounds like a long time! Upstate NY does not have a very long building season. The last frost of the year (with any luck!) was two days ago, and it can start frosting again as early September (though October is more typical). That means that with 6 pours, if I was going to wait 28 days, I would just barely have enough time -- if there were no delays and if I poured this week!

smartwall: How would I go about combining steps 1 and 2 (footing & basement wall)? In all the videos I've seen, they seem to start with a finished, set footing.

ETA: ron, you are correct, NYS code calls for minimum 7.5" thickness for concrete basement walls.

nysharps - Code - is that for reinforced concrete or just unreinforced concrete?
28 days - that is the theoretical time require to reach 90% design strength. As compressive strength is reached much quicker, ICF walls are traditional pour literally as fast as you can have them ready. I would suggest that 80% of multi storey walls are poured within ten days of each other.
My preference is to stack the basement walls to just above the main floor, install the main floor assembly, square and level and then pour the walls. Repeat main floor wall stack, install second floor and pour main floor. Stack and pour second floor walls and set trusses. The advantage of placing the floors prior to pouring are several. You have time to make sure the floor system is perfectly square therefore the walls attached to it will also be. You don't have to worry about straightening the walls after the pour. You have the whole floor to stand on to pour the walls not just narrow walkways. The floor system provides a diaphragm that prevents much of the torsional tensions on the ICF wall so you only have to worry about achieving compressive strength between pours.
Preferable you want to make your joins close to the lateral supports (floors) as possible. This prevents any possible domino action that you might get if you had a cold joint at mid wall.

So in other words 2-3 days between pours should be sufficient setting time?

The code prescribes wall thickness and reinforcement based on the height of the wall and the amount of backfill. A 7.5" thick wall can be "plain concrete" (I assume that means unreinforced) up to a wall height of 7. After that, reinforcements are needed if the backfill is more than 7'. Which should not be an issue in my case. If I'm reading this correctly (it's table 1805.5(5):
http://publicecodes.cyberregs.com/st/ny/st/b200v10/st_ny_st_b200v10_18_sec005.htm

I assumed that because the smallest thickness listed was 7.5", anything under that would not be acceptable.

Does unreinforced concrete mean no rebar in the concrete at all?

Posted By nysharps on 25 Apr 2013 06:32 PM
I assumed that because the smallest thickness listed was 7.5", anything under that would not be acceptable.

Does unreinforced concrete mean no rebar in the concrete at all?

Don't even consider no rebar. 6 inch all the way up will work. The footing will have to be thick and wide enough to support the weight of the wall, plus all the interior dead and live loads, plus roof snow load, for the soil load bearing rating per local building code. As FBBP says, footing first (unless you use something like FastFoot), then the basement wall, then install the floor, then the first floor wall, then the second story floor, then the second story wall. You'll have plenty of time with the stacking of blocks and building floors for each pour to set sufficiently.

Search the forum for a discussion of ICF gable. Unless you're building for a hurricane force wind it's somewhat of a toss up which way is better, ICF or wood. I did wood gables with 6" spray foam insulation for ease of construction and cost.

You say you have no experience with ICFs. How about home construction in general, or other construction? How cold are you coming into this project? If ICF is the only really new aspect, you'll have no problem. If the entire project is new then you really need to have a good contractor work with you.

I wasn't considering no rebar... I was just wondering what the code meant when it said "plain concrete"

I've never done a new home build before and I've no experience with foundations. I've done at least a little bit of all the rest: stick walls, floors, finish work, etc. I was planning to have a contractor help me with at least the footing and the roof.

I think you missed the "can usually be shortened" part after I mentioned the 28 days 2-3 days might be a little too fast, but unless you have a big crew prepping the blocks and fabbing the rough openings, as well as installing the floor systems, that might be a little hard to get a wall prepped and inspected in 2-3 days before the next pour...

I don't see it being done without rebar... Their reference to "Plain Concrete" is probably a reference to it's compressive strength. Wall horizontal re-enforcement should be around 1.8 percent of the wall cross sectional area and the prescriptive tables exceed this. IE: a 16" X 6" wall crosssection has 96 sq/in of area. 1.8 percent of that is .1728 sq/in. #4 rebar has a cross section of just under .2 sq/in, so one horizontal stick every 16 vertical inches of wall is sufficient. Vertical re-enforcement will be a factor of backfill, wall height and weight supported. There are prescriptive tables for the required re-enforcement if your structure falls within the scope of the tables. What are the dimensions of your planned home?

Posted By nysharps on 26 Apr 2013 12:05 AM
I've never done a new home build before and I've no experience with foundations. I've done at least a little bit of all the rest: stick walls, floors, finish work, etc. I was planning to have a contractor help me with at least the footing and the roof.

What's the situation with home financing in your area? Unless you are able to self-finance this project be aware you may run into some significant challenges. Depending on the practice in your area if you are financing the construction you may have to have a contractor in charge of the entire project. Banks in many areas of the country simply will not loan for DIY builds. When I built my house I had to have an established contractor on the construction loan paperwork as the builder, even though I was my own GC.

In any case you need to work hand in glove with a knowledgeable ICF contractor, even if it is just your supplier. Building with ICF is not hard, but it is d*** easy to screw it up, and seriously at that. In my case my block distributor gave me a lot of guidance, and I observed an ICF pour of his before I started my house. My concrete contractor was a well experienced concrete man, albeit with quite limited experience with ICF. He constructed the footings and placed all the concrete. I did the calculations to determine footing size and the building inspector had no problem with that.

If you've read through these forum topics you have undoubtedly read many comments pro and con about DIY builds, some of them rather vociferous one way or the other. My build was a DIY, but I had good contractors working with me. I also did my own design and drafted my own plans. I spent a year doing all the preliminary stuff and built the house at least a half dozen times in my head before we broke ground. There were some hitches along the way, some of my doing and some not. I ended up with a very high quality house, well built but with very little 'bling' and pretty stuff.

A DIY house is perfectly doable, but it ain't no walk in the park nor a piece of cake. You've got to have a lot of self confidence, be technically proficient, be able to figure things out, and be willing to ask for advice from others and listen to it.

Good luck. It's a great adventure!

Actually NY code , where i do most of my business has the Prescriptive Method in is the codes and will allow a 5.5 inch icf wall if the rebar schedule is followed in reference to soil type and back fill height, I'm starting one in Keesville NY tomorrow with all 6" walls. I read here that someone was stating that you can fill icf's at 4 ' height . True but not the best way to do it. I don't know how many of these things I've poured but I fill in three lifts on 8' high walls, higher that that I would do 4 lifts. The first lift is the one that causes the most problems so why rush it .. This course is the hardest to vibrate and the one where the voids will be most often found as well as the areas of course overlap. Forget the pencil vibrator it's worthless unless you are pouring a 4" wall with high range water reducer. 1.75" is the one I use. Nysharps I sent you a PM with contact info. Also no one waits 28 days to work on icf, that would be crazy. That's the time it takes concrete to reach full hardness, not the amount of time you need to stay off it. They're pouring a bridge deck on the Adirondack Northway on weekends and the lane is open by 6AM Monday,

Posted By dmaceld on 26 Apr 2013 01:55 AM

What's the situation with home financing in your area? Unless you are able to self-finance this project be aware you may run into some significant challenges. Depending on the practice in your area if you are financing the construction you may have to have a contractor in charge of the entire project. Banks in many areas of the country simply will not loan for DIY builds. When I built my house I had to have an established contractor on the construction loan paperwork as the builder, even though I was my own GC.

In any case you need to work hand in glove with a knowledgeable ICF contractor, even if it is just your supplier. Building with ICF is not hard, but it is d*** easy to screw it up, and seriously at that. In my case my block distributor gave me a lot of guidance, and I observed an ICF pour of his before I started my house. My concrete contractor was a well experienced concrete man, albeit with quite limited experience with ICF. He constructed the footings and placed all the concrete. I did the calculations to determine footing size and the building inspector had no problem with that.

If you've read through these forum topics you have undoubtedly read many comments pro and con about DIY builds, some of them rather vociferous one way or the other. My build was a DIY, but I had good contractors working with me. I also did my own design and drafted my own plans. I spent a year doing all the preliminary stuff and built the house at least a half dozen times in my head before we broke ground. There were some hitches along the way, some of my doing and some not. I ended up with a very high quality house, well built but with very little 'bling' and pretty stuff.

A DIY house is perfectly doable, but it ain't no walk in the park nor a piece of cake. You've got to have a lot of self confidence, be technically proficient, be able to figure things out, and be willing to ask for advice from others and listen to it.

Good luck. It's a great adventure!

We are self-financing, so that's not an issue.

Unfortunately, I don't personally know any ICF contractors in our area. The ICF suppliers (that I'm aware of) are hardware stores, so they don't actually do any work themselves and I can't really come at them from that angle. Otherwise, some hands-on experience or even just a chance to observe would be great.

I'm certainly not expecting house-building (ICF or otherwise) to be easy, but I enjoy challenges of that kind and I'm very much looking forward to getting my hands dirty with this project. I'm a hobby woodworker, so I at least know how to make things square, plumb and level ... and my wife and I chose ICF because of the numerous other benefits (insulation, sound-proofing, strength) not the "it's easier" marketing.

smartwalls: PMed you back

Posted By smartwall on 26 Apr 2013 10:49 AM
Actually NY code , where i do most of my business has the Prescriptive Method in is the codes and will allow a 5.5 inch icf wall if the rebar schedule is followed in reference to soil type and back fill height, I'm starting one in Keesville NY tomorrow with all 6" walls. I read here that someone was stating that you can fill icf's at 4 ' height . True but not the best way to do it. I don't know how many of these things I've poured but I fill in three lifts on 8' high walls, higher that that I would do 4 lifts. The first lift is the one that causes the most problems so why rush it .. This course is the hardest to vibrate and the one where the voids will be most often found as well as the areas of course overlap. Forget the pencil vibrator it's worthless unless you are pouring a 4" wall with high range water reducer. 1.75" is the one I use. Nysharps I sent you a PM with contact info. Also no one waits 28 days to work on icf, that would be crazy. That's the time it takes concrete to reach full hardness, not the amount of time you need to stay off it. They're pouring a bridge deck on the Adirondack Northway on weekends and the lane is open by 6AM Monday,

What smartwall says. If for some reason you need to push the pour, I would sooner do 3 and 5 than four and four. Once the bottom 3 feet have kicked over, you are pretty much good to go.