Shop Drawings vs. Erection Drawings
Shop drawings and erection drawings are both produced during structural steel detailing, but they answer different questions for different audiences. Shop drawings tell the fabrication shop how to build each individual piece or assembly: dimensions, materials, connection details, welds, and bolt information. Erection drawings tell the field crew where each piece goes and how the structure comes together.
A shop drawing is piece-specific. It typically shows a single member or a small assembly in enough detail for a shop fabricator to cut, drill, weld, and mark it correctly, with a unique piece mark tying it back to the overall structure.
An erection drawing is structure-specific. It shows a floor, elevation, or area of the building with every piece mark placed in its final position, along with the information an erection crew needs to sequence the lift and make field connections — bolt types, field welds, and any erection aids.
Both sets need to agree with each other and with the anchor bolt plan down to the piece mark. A discrepancy between a shop drawing and its corresponding erection drawing is one of the most common sources of field rework, which is why revision control and cross-checking between the two sets is a core part of a disciplined detailing workflow.