Im thinking of building a new house, and have started to draw it up on revit. I have looked into building on plies (almost a must up here in Manitoba) the spec on Arxx site shows it done the same way you would do a standard basement or grade beam, just frost cushion between the piles and blocks sitting on top of that. But to me it would seem pretty unstable just sitting on the foam cushions. I was thinking of doing a footer on the piles with a frost cushion under it, just to be sure I can get the wall nice and level. I guess I could get a wider cushion and compact some lime stone under it between the piles to insure a solid starting point. Any thoughts on this, any ideas on how to make sure its solid and will not shift.. Would you just pour the wall 2 feet or so and have a cold joint lower down in the wall? thanks

I would do the typical grade beam on top of the piles and make sure the grade beam has void form below it, between the piles. The grade beam can be built perfect and level and start your block on top of it.

Piles with a beam across them just thick enough to support the wall's weight sounds most practical to me.

Fallguy - Are you doing piling under a full basement or are you starting at grade level? If I understand the conditions you are facing the piling is to by pass expansive soils. That being the case you would be stacking 8 or 9 feet of wall on top of the piles? I understand the concern with stability but you might try laying out you first course on top of the frost cushion and than screwing a 2x to each side of the block. Even with the bottom or top to hold everything level. Than you drive 2x4 stakes and screw them to the ledge, leveling as you go. With the ledger secure you can than set your strong back on the top of the ledger and proceed as normal. It is a bit more work but not as much as cribbing a grade beam.

yes the house would be built on a basement a lets say 6' down or so. then the attached garage would be built on grade, with ICF as well on piles. i was just thinking of doing the piles then using a wide frost cushion and pour a footing on top of it.. nice solid base to start with...

Remember, the frost cushions are not supposed to be supporting any weight. The beams transfer all the weight to the piles.

If you want to pour on top of piles (ie, no footing to form and pour), I would recommend pouring a pile cap at the top of each pile that is slightly wider than the blocks you are using. Be sure the top of the pile cap is about a half inch lower than you want the bottom of the block to be. One the blocks are sets, simply screw a 2x4 to either side at the bottom of the forms (they will sit on top the pile caps). Simply shim as necessary to get the forms level and you are done. Be sure to have void form between each pile, and under any protruding portions of the pile caps to ensure frost cannot heave on any surface.

This work great if you can pour the first couple feet and then form and pour the rest later. If you are pouring 8-9'+ you may want to go with a footing, as the blocks can sag in between each pile with the weight of concrete above (or extra stakes, larger lumber, etc)