Note: For the purposes of this article we will refer to them as Wedge Inserts. They are also known as Lintel Inserts, Relieving Angle Inserts, Shelf Angle Inserts, Malleable Iron Inserts and Concrete Wedge Inserts.
Like all aspects of Steel and Concrete, construction variables exist in the field that cannot be controlled and adjustments must be made to correct them. The Wedge Insert is no exception.
Prior to pouring concrete, the Wedge Insert is secured inside the plywood forms, usually at a spacing of 2’ on center. Of course, there will be variations from one to the next, both vertically and horizontally. Adding to that, during the cement pour, pressure is exerted depending on the direction the wet cement is flowing, and then, the exothermic reaction adds its own pressure, flexing the forms during the curing process. Any number of factors will apply, however, the result is the same. Variations must be adjusted for.
For this reason, the Wedge Insert has a horizontal adjustment built into it. The slot shown in the photo above allows the Askew Head Bolt to be positioned anywhere along the slot.
Note: It is essential that the full head of the Askew Bolt be in contact with the back of the slot. It should never overhang the opening at the top.
Wedge Inserts, Relieving Angle Inserts, etc. are available in two sizes as show below:
Regular Wedge Insert:
- Part Number WI-379, Bolt Diameter 3/4”, 2-1/4” wide x 3-13/16” long.
- Slot length is 2-5/8” top to bottom however the askew head bolt limits the distance it can be adjusted. The total adjustment range is 1-1/4” horizontally.
Long Wedge Insert:
- Part Number WI-380, Bolt Diameter 3/4”, 2-1/4” wide x 5-1/2” long.
- Slot length is 4-1/8” top to bottom however the askew head bolt limits the distance it can be adjusted. The total adjustment range is 2-5/8” horizontally.
There is no horizontal adjustment built into the Wedge Insert. That comes from The Relieving Angle, Lintel Angle, Shelf Angle or Concrete Angle. Rather than punching or drilling a 13/16” hole for the 3/4” diameter Askew Head Bolt, the fabricator will punch a horizontal slot. The width (height) of 13/16” remains but the length extends to the desired variable range. Common slot lengths are from 1-1/4” to 2”.
Important Note: Slot length does effect the strength of the connection and the relieving angle. It should be noted clearly on your shop drawings what the slot size should be. If not the engineer or detailer should be contacted for approval.
Working as an example, a given Relieving Angle job calls for Long Wedge inserts and a slot size of 13/16” x 1-1-/2”. The Long Wedge Insert offers a 2-5/8” maximum slot adjustment, so if the Askew Head Bolt were located dead center there would be an up or down adjustment of 1-5/16”.
On the horizontal adjustment, the Wedge Insert and Askew Head Bolt are not factors. The slot in the relieving angle is. The maximum adjustment is limited by the 3/4” diameter of the bolt. The slot is 1-1/2” long, so if the bolt were directly at the midpoint, it would have 3/8” available to travel either way.
Hence, the tolerance in the above example is +/- Vertical 1-5/16” x Horizontal 3/8”.
