The VJH is used to joint the blocks together on the first two rows on top to the footing. This allows the first two rows to behave as a single beam so that you can easily determine the high and low parts of the footing. Once this has been achieved, it is easy to wedge up the low spots so that your first two levels are perfectly level. We recommend four VJHs for each ICF joint.
We recommend using two VJHs on each corner joint as you build the rest of the wall. There is no need to hooks in the middle of your wall
