What Are Shop Drawings and How Do They Work?

Shop drawings are detailed diagrams, schedules, and fabrication instructions that a contractor, subcontractor, or manufacturer prepares to show exactly how a specific portion of a building will be built. They take the architect’s design intent and turn it into working instructions for the people cutting the steel, bending the ductwork, or framing the cabinetry. On most U.S. projects governed by AIA Document A201-2017, shop drawings move through a defined review cycle, and the contract spells out who is responsible for what at each step.

What a Shop Drawing Shows

A shop drawing goes well beyond a standard architectural blueprint. Where the architect’s drawings show design intent and spatial relationships, a shop drawing zooms in on an individual component and gives exact dimensions, material grades, manufacturer part numbers, fastener types, and step-by-step assembly sequences. Fabrication details tell a shop worker how to cut, weld, bend, or join materials before the piece ever leaves the factory floor. Installation diagrams show how the finished component attaches to the existing structure, including clearances, shimming, and connection methods.

This level of detail exists because specialized components rarely come off a shelf. Custom HVAC ductwork, structural steel connections, precast concrete panels, and curtain wall assemblies all require project-specific fabrication instructions. Without a shop drawing, a fabricator is guessing at tolerances.

Shop drawings sit alongside, but are distinct from, product data submittals. Product data consists of pre-published manufacturer literature such as catalog pages, performance charts, and spec sheets, which the contractor marks up to show which options apply to the project. A shop drawing is drafted from scratch for the specific building. Nobody pulls one off a shelf.

How Shop Drawings Get Prepared

Accurate shop drawings start with a careful read of the architect’s design drawings and the project manual, including the technical specifications that spell out required finishes, hardware, and performance standards. Paper dimensions and real-world conditions don’t always match, though, so AIA A201-2017 Section 3.12.6 requires the contractor to verify field measurements and construction criteria before submitting. By submitting the drawing, the contractor represents that the verification actually happened.¹

In practice, subcontractors send drafters to the job site to record the actual dimensions of openings, the real locations of embedded plates, and the as-built positions of columns and beams that may have shifted slightly from the design. Those measurements feed directly into the drawing. Skip this step and you end up with a perfectly fabricated component that doesn’t fit the building it was made for.

The Review Process

The Submittal Schedule Comes First

Before any individual shop drawing can be reviewed, the contractor has to establish a submittal schedule. AIA A201-2017 Section 3.10.2 requires that schedule to be submitted to the architect promptly after contract award, coordinated with the overall construction schedule, and structured to give the architect reasonable time to review each submittal.¹

The penalty for ignoring the requirement is severe. If the contractor fails to submit a schedule, or fails to deliver submittals in accordance with the approved schedule, the contractor forfeits any claim for extra money or extra time based on how long the architect takes to review. Contractors who send shop drawings in late and then blame the architect for the resulting delay usually lose that argument under A201.¹

The Contractor’s Review and Stamp

When a subcontractor finishes a shop drawing, the document doesn’t go straight to the architect. The general contractor reviews it first. Standard general conditions, including AIA A201-2017 and EJCDC C-700-2018, require the contractor to apply an approval stamp to every submittal before forwarding it. The stamp certifies that the contractor has reviewed the drawing, coordinated it with other submittals and other trades, verified field measurements and material selections, and confirmed that the drawing complies with the contract documents.

The stamp also provides a space to identify any deviations from the contract documents. Burying a deviation in the drawing itself without calling it out on the transmittal backfires, for reasons covered below.

The Architect’s Review

After the contractor’s review, the submittal goes to the architect or engineer. Under AIA A201-2017 Section 4.2.7, the architect’s review has a specific and limited purpose: checking for conformance with the design concept expressed in the contract documents. The architect is not checking every dimension, verifying quantities, or confirming installation methods. Those remain the contractor’s responsibility.¹

Review Dispositions

Architects respond to submittals using standardized stamp dispositions. The four most common are:

Approved. The drawing conforms to the design concept, and fabrication may proceed.
Approved as Noted. The drawing is acceptable with minor markups; fabrication may proceed, but the contractor must incorporate the noted changes.
Revise and Resubmit. The drawing has significant problems. The contractor must correct them and go through the review cycle again, and fabrication cannot proceed.
Rejected. The drawing does not comply with contract requirements at all. A new submittal is required, and no work can proceed.

A “Revise and Resubmit” response must include written comments explaining what doesn’t comply. Each resubmission cycle adds time, which is another reason the submittal schedule matters so much. Two or three rounds of review on a complex structural steel package can easily consume six weeks.

Action vs. Informational Submittals

Not every submittal requires the architect to take formal action. Shop drawings, product data, and samples are action submittals, and they require the architect’s express written response before the associated work can be installed. Most standard construction contracts prohibit the contractor from proceeding with any portion of the work that requires a submittal until that submittal has been approved.¹

Informational submittals, such as warranties, test reports, certificates of insurance, and maintenance manuals, document compliance without requiring a formal approval stamp. The reviewer verifies them and, if something doesn’t comply, notifies the contractor in writing with specific reasons.

Deviations and Substitutions

One of the most common procedural mistakes is trying to slip a material substitution through a shop drawing. Contractors sometimes show an alternative product in the drawing without going through the project’s formal substitution procedures. Design professionals typically reject these on procedural grounds alone, regardless of whether the substitute would actually work.

The proper route for a substitution is a separate written request submitted under the substitution procedures in the project specifications. If approved, the substitution requires a contract modification such as a change order or architect’s supplemental instruction. Once that modification is issued, the shop drawing can move through normal review.

For deviations that aren’t substitutions, the rules are equally strict. Under AIA A201-2017 Section 3.12.8, if a shop drawing shows any variation from the contract documents, the contractor must specifically notify the architect of that deviation at the time of submission. The deviation has to be called out both in the drawing itself and in the transmittal letter. Without that notice, the architect’s approval does not authorize the deviation. Federal construction contracts contain a nearly identical rule under FAR 52.236-21, which requires the contractor to describe variations in writing, separate from the drawings.¹²

Shop Drawings Are Not Contract Documents

AIA A201-2017 Section 3.12.4 states it plainly: shop drawings, product data, samples, and similar submittals are not contract documents. That distinction has real consequences. Because submittals sit outside the contract documents, they can’t change contractual requirements on their own. An approved shop drawing is not a change order. If the drawing shows something different from the contract documents and the architect approves it anyway, the contract documents still control unless the deviation was properly flagged and authorized through a change order or other contract modification.¹

The practical effect is a one-way ratchet. If an approved shop drawing calls for higher quality or greater quantity than the contract requires, the contractor may be held to the higher standard. If the approved shop drawing calls for less than the contract requires, the approval doesn’t reduce the contractor’s obligations. The contractor is effectively bound to whichever standard is more demanding.

What Architect Approval Does Not Do

Contractors frequently argue that because the architect approved a shop drawing, the architect bears responsibility for any defects in the work shown on it. The argument almost always fails. AIA A201-2017 Section 3.12.8 is explicit that the architect’s approval does not relieve the contractor of responsibility for errors or omissions in the submittal. The architect’s review is limited to design-concept conformance. Detailed dimensions, quantities, installation sequences, and construction methods all remain the contractor’s responsibility.¹

The only way a contractor can shift responsibility for a deviation is by meeting both conditions in Section 3.12.8: specifically notifying the architect of the deviation at the time of submittal, and then either receiving written approval of the deviation as a minor change in the work or obtaining a formal change order or construction change directive. Without both steps, the contractor owns the deviation regardless of the stamp on the drawing.¹

When the Contractor Provides Design: Delegated Design

Some portions of a building require the contractor to go beyond fabrication drawings and actually provide professional design services. This is called delegated design, and it changes the stakes considerably. Under AIA A201-2017, when the contract documents require the contractor to provide professional design services for a portion of the work, the contractor must hire a licensed design professional to prepare that design. All resulting drawings, calculations, specifications, and shop drawings must bear that professional’s seal and signature.¹

The owner and architect have to specify all performance and design criteria that the delegated design must satisfy, and the contractor is entitled to rely on the adequacy of those criteria. Delegated-design shop drawings must already carry the delegated designer’s written approval before they reach the architect. The architect’s review stays limited to conformance with the stated performance criteria and the overall design concept.

Liability splits in a way that catches people off guard. The project architect is responsible for the overall design and for setting adequate performance criteria. The contractor’s delegated designer is responsible for the detailed design of the delegated element. Neither is responsible for the other’s work, and they typically have no direct contractual relationship. Vague performance criteria leave a gap that neither professional may feel obligated to fill.

What Happens to Shop Drawings at Closeout

Approved shop drawings don’t just serve their purpose during construction and disappear. During the job, the contractor marks up drawings in the field to reflect actual conditions, changes, and deviations from the original design. These field markups are commonly called as-built drawings. The architect later compiles them, along with addenda, post-bid bulletins, and design revisions, into a clean set of record drawings showing how the building was actually constructed. For owners and facility managers, the record set becomes the authoritative reference for future renovations, maintenance, and system upgrades, which is why sloppy shop drawing markups during construction cause problems for years after the project is finished.

1
AIA Contract Documents. AIA Document A201-2017 General Conditions of the Contract for Construction
2
Acquisition.gov. FAR 52.236-21 Specifications and Drawings for Construction