Folks,
Planning 1 storey, 3000sf home (slab on grade) with 6.25" ICF block with various wall heights at 9'4"(7 blocks), 14' (10.5 blocks) and 17'4" (13 blocks).   Enclosing garage (800sf) as well.  Located in southern Kansas where the frost depth is 24-30".  Radiant floor heating in slab so want to insulate slab edge/bottom.

1.  ICF installation manual show a detail of ICF wall directly on the footing.  Is it acceptable to pour the floor after the walls are erected, butting it up to the wall foam?  Will the slab be adequately supported if we compact the granular material well, place VB and insulate under the slab?  Does slab need to rest on the foundation?
 
2.  Local practice is to dig a trench, pour foundation full width of footing, pour the slab, and then start stacking block on top of slab.  Do we need a drain tile at bottom of foundation or need to moisture proof the exterior of the foundation?  Obviously can't do with a trench foundation.

3.  My preference would be to excavate, pour the footing, stack the block and then pour slab.  Can we go basically up to 20' in some walls with 6.25" concrete? 

Appreciate your inputs

I am not a builder but a wannabe in a few years (took a hands on class and have been reading a lot), here is what I would do. French drain to sump with accessible cover at grade.
Use Fast Foot http://www.fab-form.com/products/fastfoot/fastfoot.html to form your footers. Depending on how you want to use your basement slab, if left unfinished then pour and set your wall bracing on that, gives a good solid level relatively clean work area. In my case I may stain most of my floor so I will want it undamaged from the support spikes and I will pour it after the basement walls are up. Also this way will lesson the chance of damaging the pex in the floor.
Hope that helps, am sure others will jump in here with more/better info.
Jim

Sorry didn't read "Slab on Grade" first. Have you looked at the "Frost Protected Shallow Foundation" process on the HUD web site? I would build with that process.
Jim

Farmboy:

Prescriptive methods limits you to a wall height well below 20', you may be able to go taller, just please use an engineer, as required by the prescriptive method for a building with walls of this type. Also, please note that wall thickness is determined by the thinnest section of the wall, for engineering, so I doubt it is a 6.25" thick wall, it is likely grooved on the interio, and the smallest dimension governs design engineering.

Mark Ross

Thanks for the replies. Talisker2: I've read up on Frost Protected Shallow Foundations and will see if any in this area. Also will read about Fast Form. PCoughlin: Roger all your inputs. Mark: Using Logix forms which are made locally and have made a mockup of some 6.25" forms to simulate a recessed window install (also have a Pella window sample). There are grooves on interior of the form but the narrowest width is actually 6.25"! Even so, your advice is well-taken.

I forgot to include a question: How does one determine the reinforcement, spanning and lintel rqmts for 6.25" when the Prescriptive manual shows 5.5" and 7"?

Farmboy:

Use the 5.5, and you will be slightly overbuilt, but fine and welll within any design requirements.

so long as your project is within the scope of the prescriptive method, although the 20' high wall, may push it outside of this.

Mark Ross