why not rebar into subgrade to help hold vertical

[Fred]

I have an install video for ICF blocks that shows the contractor placing the rebar maybe 4-6" through the footing and into the subgrade to hold vertical. I have heard that this is not a good practice. What to do. In my plans the rebar will be 10' long to stack blocks..(8'8" above top of footing. I don't see any other way to handle this except placing into subgrade. I prefer not to use 4' dowels and tie verticals to these later as the wind will be an issue in our area and I like the idea of tying the blocks to anchored verticals.

[Rich]

You've got the right idea - in my opinion it's not a good idea to place through the footing. Personally I would place 4' verticals to tie the wall to the footing (footing to have a keyway), place a horizontal at the first course height tied to the 4' verts, stack the blocks halfway up and place the 8'8 rebar into the blocks tie it at that height to the prescribed horizontals, place the rest of the blocks and tie to the horizontals as you go up.
The 4' rebar at the bottom along with the horizontals will hold the bottom solid from kickout and the 10' will give the wall the deflection resistance needed.
You might ask over at www.concrete-home.com also.

[RobBase]

Fred, Rich is correct that it is not good practice to stake your vertical rebar into the ground. The theory is that ground water will rust the rebar and the rust will travel up and begin to rust the rest of your rebar grid. On commercial and government jobs we do, inspectors will not allow footings or any other pour to go on with rebar in contact with the ground.

If I can, I will post some pictures to show how it's done.

As far as not wanting to have 2 piece wall rebar, it's perfectly ok as long as you lap any splices 40x the bar diameter. The rebar's don't even have to be tied together as long as they are in contact along the length of the lap by any means..........
I'm using Reward ICF forms for my house and they suggest, as do Fold form and others, to pour your footings with the vertical dowels coming out of the footings. Then drop a 2" long piece of PVC pipe over each dowel. The diameter of the PVC should be slightly larger than 2x the diameter of your rebar, i.e. 1 1/4" for 2 #4 rebars or 1 1/2" for 2 #5's. Then lay your blocks up to the top of wall height, afterwards you drop your full length verticals down the wall cavities and into the piece of PVC sleeves at the bottom. The sleeve will hold the rebars in contact and become your splice connection. See Fold-form.com or Reward.com installation guides for more specific details.