Shop Drawings vs. Construction Drawings: Are there Any Differences?

22 October 2019

A building developer’s desk is covered in different structural drawings. Not a single one of the drawings is alike, although one or two of them might be of the same structure. Even so, drawn from different viewpoints, they convey different information. As for the Shop Drawings VS Construction drawings issue, yes, these plans also convey contrasting sets of design and fabrication data. For one thing, shop drawings communicate workshop instructions.

A Back to Basics View: Construction VS Workshop Drawings

Let’s assume there’s a prefabrication phase going on back at the shop. The architects and project engineers have worked together to come up with a set of plans. Branching off to one side, the structural detailing department has drawn up the shop plans. They look a little like the construction drawings, focus on the same orthogonally rendered views, but the plan details highlight different features. Cut lines and bend points receive precedence on the shop drawings. Out on the construction site, after a partially fabricated structure has been transported to the site, the construction drawings are consulted. They list rigging lift zones, as assigned to a site crane. Away from the prefabricated fastener and shop weld markings, structurally significant weldments are clearly outlined, too.

Keeping the Team on the Same Page

While both workshop drawings and construction plans are made before the erection work begins, they’re meant to convey two slightly distinctive sets of technical data. With exactingly detailed shop drawings in hand, material assets are gathered, schedules are determined, and services are planned out beforehand. This is the fabrication outlining phase, where every bend and cut, material selection decision and structural steelwork element is mapped out in great detail. From here, contractors and suppliers take the lead. As for the construction drawings, they’re every bit as important. Crane services and welders rely on these erection oriented plans. They’re essentially the final plans, which are held back at the office and onsite, perhaps in a mobile headquarters.

Think of the shop drawings as a malleable design resource. They’re produced for the contractors and for the shop fabrication department, but they’re not yet written in stone. Depending on what the project design team, architect and engineers agree upon in their many meetings, several iterations of shop drawings may gather in a small pile. However, when those plans are finalized, their heavily detailed graphics can then be employed as prefabrication or preconstruction assets. Material lists and contractor hirings are now decided upon. Dimensions are added, bend angles, too, then the proposals become final worksite plans. From here, these Construction Drawings are used to guide the erection process.