made up of the ladders and core it also makes subsequent positioning of the other form 60 simple and precise since the truss 64 is held in an exact perpendicular orientation to the forms 60 62 by the vertical ladder 18 in the most convenient method for forming the inner structure of the wall prior to pouring the first form 62 is set in place then the insulation core panels 20 22 are positioned with the vertical ladders 18 between panels once the vertical ladders 18 and the insulation core panels 20 21 are in place the horizontal ladders 30 32 are slid into place as shown in fig3 since the vertical dimension 48 is less than the transverse dimension 46 of the horizontal ladder the horizontal ladder is inverted for insertion such that the lengthwise rods 40 42 are vertically positioned relative to each other adjacent the insulation core the horizontal ladder is then slid horizontally along the insulation core 12 until it spans at least two vertical ladder structures this is shown at the top of fig3 once the horizontal ladders are correctly positioned such that the v shaped transverse members 44 are directly adjacent the cross members 28 of adjacent vertical ladders the horizontal ladder is rotated into engagement with the outer wall 34 of the insulation core 12 and the vertical member 24 of the vertical ladder thus forming the v shaped aperture.