What is a shop drawing?
A shop drawing, in Dutch “werktekening”, shows exactly how a component is to be made, fabricated or installed. It is usually produced by the contractor, a subcontractor or a supplier (for example the steel fabricator, precast concrete plant or window maker), based on the design and contract drawings from the architect and structural engineer.
How it differs from other drawings
- Contract or design drawing: states what is to be built and forms part of the contract.
- Shop drawing: works this out to millimetre dimensions, connections, materials, quantities and production information.
- Detail drawing: shows a junction or component at large scale; shop drawings often contain such details.
- As-built drawing: records what was actually built.
What is on it?
- Exact dimensions, levels and positions relative to grid lines or datum.
- Sections, plate thicknesses, bolt holes, welds or reinforcement.
- Material, grade, finish and coating.
- Mark numbers so each part can be identified on site.
- Parts lists and, where needed, erection sequence.
Approval
Shop drawings are submitted to the architect, engineer and/or main contractor before fabrication. Only after approval does the component go into production. Approval usually does not relieve the maker of responsibility for accuracy; make sure the contract says so.
Practical tips
- Measure first: in renovation work, base shop drawings on site measurements, not old drawings.
- One current revision: work only from the latest approved version and remove old ones from site.
- Check interfaces: make sure openings, services and adjoining components fit.
- Allow time: drawing, checking and fabrication often take several weeks before delivery.
Related terms
- Detail drawing
- As-built drawing
- Symbols in construction drawings
- Drawing legend
- Section drawing
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