What Is a Shop Drawing and Why the Review Process Makes or Breaks Your Industrial Project
There is a moment on every industrial project — somewhere between the design phase and the first bolt being tightened on site — where everything either clicks into place or quietly starts to unravel. Most project owners never see it happening. Their engineers do. Their fabricators do. And contractors who have been in the business long enough know exactly what that moment is.
It is the shop drawing review process.
It sounds administrative. It sounds like paperwork. But ask anyone who has managed a grain handling facility build in Saskatchewan, a mining structure in Northern Alberta, or a structural steel installation anywhere across the Canadian Prairies, and they will tell you the same thing: a missed or poorly managed shop drawing review is one of the fastest ways to blow your timeline, inflate your budget, and end up with components that simply do not fit.
At Credence Construction Ltd., we have seen both sides of this equation — the smooth builds where the review process was tight and disciplined, and the projects that inherited someone else’s shortcut. Here is what every project owner and operations manager needs to understand.
So, What Exactly Is a Shop Drawing?
A shop drawing is a detailed, fabrication-ready document produced by the contractor, manufacturer, or fabricator — not the design engineer. While architectural or engineering drawings show what needs to be built, a shop drawing shows how a specific component will actually be made, assembled, and installed.
For a structural steel project, for example, a shop drawing would include exact weld locations and specifications, connection details down to the bolt size and grade, component dimensions verified against real field measurements, material grades and finishes, and the sequence in which pieces are to be erected on site.
Think of engineering drawings as the vision and shop drawings as the execution manual. One tells you where the hopper goes. The other tells the welder exactly how to build it so it fits perfectly when it arrives on a flatbed.
This distinction matters enormously in industrial construction, where prefabricated components are manufactured offsite — often hundreds of kilometres from the project location — and must integrate precisely with existing infrastructure the moment they arrive.
Why the Review Process Is Where Projects Succeed or Fail
Producing the shop drawing is only half the work. The review and approval process is where the real value is created — or lost.
Here is how a proper shop drawing review process works:
Step 1 — Preparation. The fabricator or contractor prepares the shop drawing based on the contract documents and actual field measurements. At Credence, our Drafting & Design team works directly with our fabrication and site crews to ensure the drawing reflects real-world conditions, not just theoretical specifications.
Step 2 — Internal Review. Before the drawing ever leaves our office, it is reviewed internally against the project specifications, local building codes, and safety requirements. This catches the easy errors before they become expensive ones.
Step 3 — Submission to the Engineer of Record. The drawing is submitted to the project’s architect or structural engineer for review. This is where design intent is verified against fabrication intent. Any deviations from the original specifications must be clearly flagged — not buried in the details.
Step 4 — Revise and Resubmit (if required). Complex industrial projects often require multiple review cycles. Each cycle is an opportunity to catch a problem on paper rather than on the job site.
Step 5 — Approved for Construction. Only once the drawing carries an approval stamp does fabrication begin.
The reason this process is so critical is simple: errors caught at the drawing stage cost almost nothing to fix. Errors caught after fabrication has begun cost time and materials. Errors caught after installation can cost an entire project its schedule.
What Goes Wrong When the Review Process Is Rushed
In a competitive industrial construction market, the pressure to compress timelines is constant. Shop drawing review is often where corners get cut first — and where projects pay the heaviest price later.
The most common failure modes include:
Fabrication beginning before approval is confirmed. This happens more than anyone admits. A fabricator eager to hit their production schedule starts cutting steel based on a drawing that is still under review. When revisions come back, components have to be reworked or scrapped entirely.
Deviations going undocumented. Sometimes a fabricator makes a practical adjustment — a slightly different connection detail, a modified dimension to match available stock — without formally flagging it in the drawing. If the engineer of record is not aware of the change, it can create structural or compliance issues downstream.
Field measurement errors carried into the drawing. If the shop drawing is based on design dimensions rather than verified field measurements, prefabricated components arrive on site and simply do not fit. In remote mining or agricultural locations across the Prairies, that means project delays of days or weeks while corrections are sourced and delivered.
This is precisely why accurate engineering drawings are the foundation of any successful build — a principle we explored in depth in our post on why precise engineering drawings prevent construction delays.
How Shop Drawings Connect Directly to Steel Fabrication Quality
For industries like agriculture and mining — where Credence primarily operates — the shop drawing is inseparable from the fabrication process. Every structural steel component we produce, from custom hoppers and bin systems to conveyance structures and equipment platforms, begins with a reviewed and approved shop drawing.
Our Steel Fabrication team operates out of a CWB-certified facility, which means our welders work to documented weld specifications that are captured in the shop drawing itself. The weld type, size, location, and inspection requirements are all prescribed before a single arc is struck. That level of traceability is what separates a compliant, reliable fabrication from one that is built on assumptions.
It also directly supports our Construction Solutions work. When a structural component arrives on site with a fully approved shop drawing in hand, our installation crews know exactly what they are working with — connection points, bolt patterns, erection sequence. There is no guesswork, no field improvisation, and no rework. Projects move on schedule because the decisions were made on paper, not in the field.
What to Look for in a Contractor’s Shop Drawing Process
If you are evaluating industrial contractors for your next project, the shop drawing process is one of the most revealing questions you can ask. A contractor who treats shop drawings as a formality will almost certainly create downstream problems for your project.
What you want to see is a contractor who maintains version control on all submitted drawings, flags deviations from contract documents explicitly, coordinates shop drawings across multiple trades before submission, and does not release work to fabrication until written approval is confirmed.
At Credence, our multi-trade capability — spanning drafting, fabrication, construction, and repair and maintenance — means that shop drawing coordination happens within a single team rather than across fragmented subcontractors. That continuity eliminates the communication gaps where most shop drawing problems originate.
The Bottom Line
The shop drawing review process is not a bureaucratic hurdle. It is the moment where your project either locks in quality and schedule certainty, or quietly inherits problems that will show up later at the worst possible time.
For owners and project managers in agriculture, mining, and heavy industry across the Canadian Prairies, understanding and demanding a rigorous shop drawing process is one of the highest-value things you can do for your project before construction even begins.
If you are planning a new build, a facility upgrade, or a maintenance shutdown that involves structural or fabricated components, connect with the Credence team early. The right conversations at the drafting stage are always cheaper than the right corrections at the fabrication stage.
