I have noted that there seems to be two different methods for pouring the basement slab in ICF homes. One method is to place the footings then pour the slab then install the basement wall stacks and then pour the basement walls. Another method is to place the footings , then lay the basement wall stack and then pour the basement walls , then install the main level floor , then pour the basement slab. Are there reasons for the differences, and is one method better than the other. It seems to me that if you are using radiant heat in your basement floor, you have be to be careful with the bracing for the walls to avoid penetrating your embedded tubiing. So if you are using radiant it may more sense to use the second method. Also, does the geographic area (northeast, midwest, northwest) dictate the method used? Thanks JW

Great question, I too have wondered the reasoning for why people choose one method over another. I have seen photos of varying installation methods.

 

I personally, more often than not, don’t even get the slabs poured until the roof is on. Being in the North East (Maine) we are often competing against the ever changing seasons, especially frost in the fall/winter. This also helps keep my crews off any newly poured slabs which will get scratched up pretty easily in the first week or so.

 

I am switching over to using suspended concrete floors, so I expect that I will have coordinate the slab pours with subsequent wall pours to be able to utilize scheduled pump truck rentals.

 

I would love to hear from others on this one.  

Here in Southern Oregon, we enjoy 200+ days of sunshine, so coordinating a slab pour isn't all that difficult. Determining the phase at which to pour one is sometimes. If it will be a decorative, or a slab that will be seen after construction, we don't want a bunch of holes all over the place from achoring out turnbuckles. So, we'll set up our bracing on the outside of the walls. Sometimes this can create more work for you but obviously we must keep the finish product in mind, not what works best for us all the time.
Another thing we have done depends on the shape and access of the structure. If it gets complex or tight, etc. We will set it up like this: footings, first two or three courses (reinforced and poured), and then set up and pour the slab(s). This makes it easier on us or the finishers to come in and work their magic. But, it once again reverts to whether the appearance of the slab is important or not; as to whether or not we set up our bracing on the inside or the outside.
We set up the ICF walls for a customer one time and ran the different scenarios by him, and he told us to stack and pour the two stories in two pours (common) and let him worry about the slab pour later. He installed his floor system for the second floor shortly after we poured the first twelve feet, and quickly realized how difficult he had just made the flatwork on himself. It was so dark in some corners of the building or tight in others, that no matter what way you looked at it, it was gonna be a chore.
Hope this helps you some.

Jesse
ICF Pro Builders
Southern Oregon

Hi jperod:
Hi Jesse:

jperiod: in addition to the options you have laid out, there is one more of the monolithic slab where one will place concrete (pour) the basement slab and footings together.

You have correctly pointed out that if there is going to be radiant heat tubing in the basement slab then one will have to be careful about anchoring the bracing -- but this is just a matter of planning where the bracing would be installed, laying out the tubing, showing it on a sketch and marking off an area that is safe to install the bracing on.

Jesse: as far as messing the slab up, we have not experienced that -- you may want to look at our recent project: Pam and Gary Stehr's House in Highland Twp Michigan at http://www.energyefficientbuild.com where we did use the monolithic slab. The advantage with having the basement slab done before stacking the ICF walls is you have a neat, level surface to work on. And yes, for waterproofing concerns we did use a waterstop at the interface of the basement slab and the ICF wall.

And by the way, having the basement slab in addition to having the First Floor Decking in place before placing the backfill also helps.

I have a few customers that pour the footing, place 1-2 courses of ICF and then pour there floor first which I prefer myself for ease of moving around and fatigue. As you mentioned this is a basement job and the weather will dictate your project. As far as pouring the slab first with radiant, just glue (spray foam) a block of wood 2" x 6" x 12" or so to the floor where the foot of the alignment rest and screw to that with 2-1.25" screw's. We have poured walls 16' tall like this with no problems.
To remove hit block on end with hammer.

Dave

Dave, I like the idea of pouring the 1-2 course but, wouldn't that be a bad spot for a cold joint for below grade? Do you see the plans calling for anything special for that joint?

Thanks
Joe

Thanks Tom, the no concrete makes sense to me now.

Thanks
joe

As I mentioned all job scenarios are different, if you plumbing and or heating contractor Isn't on schedule with you, you may have to move on without him and stack and pour without the floor. I also have guys who pay the excavator to over dig, brace to the outside and pour the walls and floor simultaneously to get out with one pump fee. (minimum charge) The walls generally take less than two hours and the same with the floor.

Dave

Jperiod; I build in Minnesota where we are never more than 5 min away from a change in weather it seems. We have become very focused on pouring the footing and the floor before setting the walls. Here is why we have a heavy clay content soil for the most part so every time it rains we have a mud hole to work in (land of ten thousand sloughs you know) it is great to work on solid ground. we use one of the products that holds our floor heat tube in place very well so we do not worry about screwing into the tubing below on a 4" slab just use tap cons that are no longer than 1 1/2". The holes that are there after the job is complete are filled or glazed over with a leveler product available at most hardware stores or building center. The great part is that we can power trowel the floor out to our rebar stubs so we do not have any one on their knees for finishing. We do lay out poly when we pour the walls to reduce the spill factor, and granted the concrete will get some scratch's in it but that is minimal and most of of us Sweds, and Norskys put a hard wood floor over top of the concrete any how. If you schedule it with your subs it works pretty good or at least here it does we have some very good subs for any thing that goes in the floor before the pour. With the floor poured ahead of time we have also reduced our twisted ankle problem, and our slip in the mud and fall, granted it has cut into our comedy relief but at least no one is going to the hospital. We always use a pump for our floors and footings, I have found that the extra expense for this is equal to or less than the added labor hours due to the efficience of pumping, and the risk of back injury pushing a wheel barrow is eliminated as well as the risk of tripping over the heat tube and pulling it up through the concrete. There is no hard and fast rule in regards to doing it this way but if you try it a couple of times you should discover what we did and that is you will save money and time on your build. One more item to mention, because we have a cold seam at the point where the wall and the floor meet we run a 1/2" bead of butyl caulk where the center of the wall will be to help create a seal against potential leaks, as well as waterproof the outside of our walls.

Although I believe the glue method works, there was another way I read about a few years ago.

Now this depends on what materials and methods you have available butif yu wet down the floor slab, and circulate water that is warmer than the slab, the areas that dry first re where the tubes are located