Both BCI® and AJS® joists are manufactured with perforated knockout holes spaced at 12” on-center and having a diameter of 1.5 inches. These knockouts may be removed in the field for wiring, small flexible pipe, or ventilation. BCI® / AJS® joist shear capacities, including reductions for web holes, are determined through testing that is performed on joists manufactured with the perforated knockout holes. Since the testing accounts for the factory cut knockout holes, the following provisions apply:
- Minimum hole spacing requirements do not apply to field cut web holes that are cut adjacent to knockouts.
- Knockout holes that fall directly in bearing zone areas (bottom 6” of web x 6” wide from bearing edge area from end or either side of intermediate bearing) may be removed, but no other web holes may be cut.
- A minimum distance of 1/8” should always be maintained between the edge of the hole and the top/bottom flanges.
- A group of round holes at approximately the same location is permitted if a single round hole circumscribed around them meets the hole conditions specified in the AJS® / BCI® Specifier Guides.
- Additional 1.5” diameter field-cut holes may be located at any location along the joist length with the following exceptions
- When located adjacent to other field-cut web hole greater than 1.5” diameter, a minimum edge distance of 3” is required.
- No field-cut holes of any diameter are allowed in bearing zone areas
Web holes shall be located by hole charts found in BCI® / AJS® literature or the BC Calc® sizing software. For further information, please contact Boise Cascade EWP Engineering.