- Shop drawings translate the design into details that can be built on site.
- Cross-discipline coordination in drawings prevents clashes before they reach site.
- Organised submittals with a clear log shorten the approval cycle.
- No work before approval — building from unapproved drawings risks rework.
The consultant's design drawings show what must be built, but they rarely show in enough detail how to build it. That is the role of shop drawings: drawings prepared by the contractor or its technical office to show exact dimensions, sections, service routes and fixing details, based on the materials and equipment actually approved for the project.
Design drawings vs shop drawings
- Design drawings: set out the concept, requirements and systems; prepared by the consultant.
- Shop drawings: detail how the work will be built using the approved equipment and materials, coordinated across disciplines; prepared by the contractor and approved by the consultant.
- As-built drawings: record what was actually built and are handed to the owner at completion.
When do you need shop drawings?
Whenever details depend on the supplied product or interact with other trades: ductwork, electrical and plumbing routes in ceilings, mechanical and electrical plant rooms, façades and aluminium, steel structures and reinforcement details in complex elements. Specifications usually list the shop drawings required before each activity starts.
Coordination between disciplines
Their biggest value is catching clashes on paper: a duct running through a beam, drainage without enough fall because of ceiling height, an electrical panel with no maintenance clearance. A coordinated drawing combines the disciplines in one drawing and sets the level of each system, so the problem is solved in the office at almost no cost instead of on site through demolition and rework.
A clash found on a drawing costs an hour of revision; the same clash on site costs days and materials.
How shop drawings get approved
- Materials first: shop drawings are based on approved equipment, so the material submittal comes first.
- Submission: the drawing goes with a transmittal stating its number, revision and the specification it responds to.
- Review: the consultant returns it with one of the usual statuses: approved, approved with comments, revise and resubmit, or rejected.
- Close-out: comments are addressed and a new revision submitted until approval, all recorded in the submittal log.
Tips to reduce resubmissions
- Build a submittal schedule linked to the construction programme.
- Check each drawing internally against the specification before sending.
- Answer every comment clearly in the next revision.
- Keep an up-to-date submittal log showing status and dates for each revision.
FAQ
Who is responsible for preparing shop drawings?
The contractor or its technical office; the consultant reviews and approves them. The contractor remains responsible for their accuracy and fit with the site.
Can work start before a drawing is approved?
Not advisable — work built from an unapproved drawing can be rejected and removed at the contractor's cost.
How long does a shop drawing approval take?
The contract usually sets review periods; the real duration depends on submission quality. Coordinated, complete submittals tend to pass on the first or second review.
Engineers and specialists in government tenders, technical office, MEP and central HVAC, with more than 15 years in the Saudi market.
