Gusset Plates use 18 gauge steel with what penetration?

• A. 16 Gauge with 1/2 inch penetration
• B. 18 Gauge steel plates with 3/8 inch penetration
• C. 20 Gauge with 1/4 inch penetration
• D. 22 Gauge with 3/8 inch penetration

Answer: (B)

Gusset plates are thin metal plates used to reinforce joints, so the combination chosen for these plates is about providing enough strength while staying practical to fabricate and install. An 18-gauge steel plate is thick enough to carry the loads typical in these connections but light enough to handle easily, since 18 gauge is roughly 0.0478 inches thick. The 3/8 inch penetration refers to the hole size in the plate for fasteners, meaning a 3/8 inch hole to accommodate a standard 3/8 inch bolt. This pairing—18 gauge thickness with a 3/8 inch hole—gives a good balance of strength, weight, and compatibility with common hardware. The other gauge and hole size combinations would either be unnecessarily heavy or too weak, or would not fit standard bolts cleanly.