# Box Sections

The figure shows the location of holes and clipped corners, which must be flush. Using the following formulas, the table shows typical sizes of holes.

Internal Gussets

• Space at minimum of 36 (91 cm)

Box Sections

• If H + W = 24 (61 cm) or larger, the area of the hole, plus clips, should equal 25% of the cross-sectional area of the box (Area = H x W).
• If H + W is between 16 and 24 (41-61 cm), the area of the hole, plus clips, should equal 30% of the cross-sectional area of the box.
• If H + W is between 8 and 16 (20-41 cm), the area of the hole, plus clips, should equal 40% of the cross-sectional area of the box.
• If H + W is less than 8 (20 cm), leave completely open, with no end-plate or internal gusset.

The table below is for square box-sections only. For rectangular sections, calculate the required area and check with the galvanizer for positioning of openings.

Box Size Holes A-Dim (H +
48 (122 cm) 8 (20 cm)
36 (19 cm) 6 (15 cm)
32 (81.3 cm) 6 (15 cm)
28 (71 cm) 6 (15 cm)
24 (61 cm) 5 (12.7 cm)
20 (50.8 cm) 4 (10.2 cm)
16 (40.6 cm) 4 (10.2 cm)
12 (30.5 cm) 3 ( 7.6 cm)