Just wondering if anyone has poured a cold climate monolithic slab instead of standard footings and 4" slab for the basement floor. My thought is that I could eliminate a pump truck visit when I start my storm shelter project also screeding and finishing a mono slab would be alot easier than doing it with the icf walls in place. The bottom of the footings will be 13' below grade with the frostline at 48".  My hope is to get started by Halloween but due to the temps we get here it may have to wait till Spring.

“The enemy of a good plan is the dream of a perfect plan.” ― Carl von Clausewitz

Just make sure you install a waterstop in the slab where the ICF walls are to go, we generally place it flush with the dowels. It is an extra layer of protection which is really important here as your slab will not be higher then the bottom of the wall, as it would be if you poured the slab after walls are completed.

Posted By yayoubetcha on 05 Oct 2013 10:29 PM
Just wondering if anyone has poured a cold climate monolithic slab instead of standard footings and 4" slab for the basement floor. My thought is that I could eliminate a pump truck visit when I start my storm shelter project also screeding and finishing a mono slab would be alot easier than doing it with the icf walls in place. The bottom of the footings will be 13' below grade with the frostline at 48".  My hope is to get started by Halloween but due to the temps we get here it may have to wait till Spring.

“The enemy of a good plan is the dream of a perfect plan.” ― Carl von Clausewitz

I love to do monolitic pours, it eliminates additional steps , saves time and money
but I am in a warm climate,
I also have experience building homes with full foundations in cold climates and the poured slab seperately is beneficial to brace the base of the basement wall and keep it from caving in when the outside is backfilled
unless there is a detail or plan to keep the wall from pushing in, It does not sound like a good idea

A slab with no footing should have a thickened edge and vertical rebar embedded to keep the ICFs from moving inward.

Sounds similar to what we just did with a 32' x 25' addition foundation, where we poured the footing, walls and floor in one single pour. We used a line pump since speed of the pour wasn't a consideration

smartwall - reading between the lines, I'm guessing you pour footing and wall mono and came back to pour the floor when done with the walls. Also I assume you had placed drainage rock for the slab.
This would provide separate support for lateral pressure at the bottom of the wall and also look after Chris's concern with leakage.
Btw what time did your floor finishers get to go home?

Thanks for the reminder about the inward force on the base of the walls... Finding an engineer in Minnesota with exprience in this type of construction seems to be a bit challenging. I will be calling a few more tomorrow.

Worked right along with the excavator. When he finished we set up the form-a-drain and he backfilled the interior to height with stone. As for the floor , it was poured after the first truck was used to pour the footing and part of the wall. I poured a 4000 lb, 2 slump and added Fritz-Pak mid range as well as an accelerator. The finisher wrapped up at about 2PM

I love to do monolithic pours, it eliminates additional steps , saves time and money and have done half a dozen in the North East. We went below the frost line (42") set the forms, placed the rebar etc along with 6 mil poly vapor barrier with 3/4" trap rock under the slab area - and off to the race!

Fast, and if well thought out you will have no problems.

RL

smartwall - how do you keep the concrete in the walls from pushing up through the footer - just a timing\slump thing? Form-a-drain doesn't help with that, unlike Fastfoot which contains the concrete. Do you do it in 2 passes - pour say 6" of the wall with the footer, and then come back again and pour the other 42"? thanks

Timing and slump are the right answer. The reason for the form-a-drain was the fact that we also poured the floor at the same time. Something that the boys at Fastfoot can't do even though they have a great line of products. I use their forming product to pour stepped footings. It saves a tremendous amount of time

We do mono footings/slabs often, both for basements and crawlspace 'rat slabs' Hopefully this expanation helps, as we can't post link here....

We use two by six lumber for the vertical form, and bevel the top in a tablesaw at 5 degrees. Then screw another two by six to the first, to make a 95 degree L. Strike the concrete floor off the lip of the aformentioned 2 by six.

Basically after the pour, the inner ICF face is ripped down 1.5 inches on a tablesaw, and sits on the finished concrete slab. The outer eps sits down lower, on a concrete shelf which now slopes 5 degrees downward towards the weeping tile.
So this method takes care of concrete keyway/shear, waterstop, one only forms one side of footings (we still use fastfoot) and one does not have to hand trowel edges of the concrete slab against the walls....

Any thing over 12 corners we do conventional, or when we can't get plumbers to play along with us....

But you are not pouring the footing, floor and the walls at the same with this setup are you?

where we poured the footing, walls and floor in one single pour.

Sounds like a video would be useful to show others how.

irnivek, a pic or more detailed explanation would help. Thanks.

My understanding is that you add the wall later, just mono pour the footing + slab

I get you want a slope on the exterior portion of the footer for drainage.

I get that you don't want the wall to move while backfilling, but not sure of the mechanism. Is the slab higher than the bottom of the wall?

Like this? (w=Wall, F=Footer, S=Slab), shown is 45 degree angle for F, not 5.

		W
		W	S	S	S
	F	F	F	F
F	F	F	F	F

@ Sharter, that looks right.
@ smartwall, we may choose to pour footings and slab together only, not walls. Haven't yet seen a method that is effective in sand, mud, pitrun gravel, wind to allow me to set protocols to do this proficiently....

This is great way to lower construction cost and couple your foundation to a stable earth temperature.

A frost protected slab, typically 4” concrete with a thickened perimeter footings rest on a variable thickness of foam. In many area of Michigan the horizontal skirt foam is not needed. Skirt foam is typically 1” x 4' that is laid outside of the building envelope a foot or so below grade.

You need stable drain-able soil to build this way. In some cases you can just remove the top soil and start setting forms.

When we build this way, we set the first course of ICF and wet set the vertical bar full height.

In many area of Michigan the horizontal skirt foam is not needed.

This is for soils where frost heave cannot occur?

Have you looked at any raft slab systems? They are super insulated monolithic slabs that can be installed in many soil types including high frost susceptible, low bearing, permafrost ect. They are extremely easy to install and are very energy efficient an readily lend to the application of radiant heat systems

I kind of like this idea. Lay out foam first to insulate the whole slab/footing. http://www.jlconline.com/formwork/super-insulated-slab-foundations.aspx