Shop Drawings vs IFC Drawings What Project Owners Need to Know

Construction projects depend on accurate drawings, but not all drawings serve the same purpose.

Two of the most important drawing types used during project execution are IFC drawings and shop drawings.

Although both are essential, they are developed by different parties, at different stages, and for different objectives.

Understanding the difference between shop drawings vs IFC drawings is especially important for project owners, consultants, and general contractors because confusion between the two can lead to incorrect construction, coordination problems, delays, and unnecessary rework.

IFC drawings communicate the approved design intent, while shop drawings translate that design into detailed information that contractors and fabricators can actually use for installation or fabrication.

A successful project needs both.

What Are IFC Drawings?

IFC stands for Issued for Construction.

IFC drawings are the approved design drawings released for use during construction.

They are typically prepared by the project’s consultants or designers and may include:

• Architectural drawings
• Structural drawings
• Electrical drawings
• Plumbing drawings
• HVAC drawings
• Fire protection drawings
• Infrastructure drawings
• Landscape drawings

The IFC set should provide the contractor with sufficient information to understand what needs to be built.

For example, structural IFC drawings may show:

• Column locations
• Beam sizes
• Slab thicknesses
• Structural grids
• Reinforcement requirements
• Foundation dimensions

However, IFC drawings do not always contain every fabrication or installation detail required by the contractor.

That is where shop drawings become important.

What Are Shop Drawings?

Shop drawings are detailed drawings prepared by contractors, subcontractors, manufacturers, or fabricators based on the approved design documents.

They show how the work will actually be fabricated, assembled, coordinated, and installed.

Shop drawings may include:

• Exact dimensions
• Material details
• Connection details
• Equipment locations
• Supports
• Fixings
• Fabrication details
• Penetrations
• Openings
• Installation clearances
• Coordination with other systems

For example, an IFC drawing may show the general location and size of a steel beam.

The structural steel shop drawing may go further and show:

• Connection plates
• Bolt sizes
• Weld details
• Member markings
• Fabrication dimensions
• Erection references

The same principle applies across many construction disciplines.

The Main Difference Between Shop Drawings and IFC Drawings

The simplest distinction is:

IFC drawings define what must be constructed.

Shop drawings define how the contractor intends to construct it.

IFC drawings communicate design intent.

Shop drawings convert that intent into practical execution details.

This difference is important because shop drawings should not independently redesign the project.

If the contractor discovers that the approved design cannot be executed as shown, the issue should normally be raised for technical clarification rather than silently modified through the shop drawing.

Who Prepares IFC Drawings?

IFC drawings are generally prepared by the design consultant or project designer.

Depending on the project, this may include:

• Architects
• Structural engineers
• Mechanical engineers
• Electrical engineers
• Infrastructure engineers
• Specialist designers

Before being released for construction, the drawings may go through several stages such as:

• Concept design
• Preliminary design
• Detailed design
• Tender drawings
• Revised design
• IFC issue

Once formally approved and issued, the contractor uses the IFC package as a primary basis for construction planning and shop drawing development.

Who Prepares Shop Drawings?

Shop drawings are typically prepared by the party responsible for executing or fabricating the work.

Examples include:

• Structural steel fabricators
• MEP contractors
• HVAC contractors
• Electrical contractors
• Plumbing contractors
• Fire protection contractors
• Façade contractors
• Joinery contractors
• Ceiling contractors

A general contractor may coordinate the overall shop drawing process even when specialist subcontractors prepare individual packages.

This coordination is critical because one contractor’s shop drawing may affect another trade.

Why Shop Drawings Are Necessary

Construction cannot always be executed directly from design drawings.

The contractor often needs additional detail to turn the design into physical work.

For example, an HVAC IFC drawing may show the required duct route.

The shop drawing may need to show:

• Exact duct dimensions
• Elevations
• Fittings
• Dampers
• Supports
• Access requirements
• Coordination with cable trays
• Coordination with sprinkler pipes
• Ceiling clearances

Without this level of detail, installers may encounter conflicts once work reaches the site.

Shop Drawings Help Detect Construction Clashes

One of the most valuable functions of shop drawings is identifying conflicts before installation.

Imagine a ceiling zone containing:

• HVAC ducts
• Sprinkler pipes
• Plumbing pipes
• Cable trays
• Lighting fixtures
• Ceiling supports

Every system may fit individually on its own design drawing.

The conflict appears when all systems are overlaid.

Coordinated shop drawings can reveal that:

• A duct crosses a structural beam
• A sprinkler pipe conflicts with a cable tray
• A light fixture overlaps an air diffuser
• A pipe blocks an access panel
• Required maintenance clearance is unavailable

These problems can then be resolved before construction.

IFC Drawings Should Be Reviewed Before Shop Drawing Preparation

Contractors should not begin developing detailed shop drawings without first reviewing the IFC package.

The review should identify:

• Missing information
• Conflicting dimensions
• Drawing inconsistencies
• Incomplete details
• Coordination issues
• Differences between drawings and specifications

If clarification is required, an RFI in construction may need to be raised before the shop drawing can be finalized.

This prevents the contractor from building assumptions into the shop drawing.

What Happens During the Shop Drawing Approval Process?

Once prepared, shop drawings usually go through a formal submittal and review process.

A typical workflow may include:

1. Specialist subcontractor prepares the drawing.
2. Main contractor reviews it.
3. Internal coordination is completed.
4. Drawing is submitted to the consultant.
5. Consultant reviews against design requirements.
6. Comments are issued.
7. Contractor revises the drawing if necessary.
8. Final approval is obtained.
9. Approved shop drawing is released for execution.

The exact approval status terminology varies between projects.

Typical responses may include:

• Approved
• Approved with comments
• Revise and resubmit
• Rejected

Construction teams should always confirm that they are working from the latest approved revision.

Approved Shop Drawings Do Not Replace the Contract Documents

This is an important distinction.

Shop drawing approval does not necessarily transfer design responsibility from the contractor or eliminate contractual requirements.

The contractor is still responsible for verifying:

• Site dimensions
• Fabrication accuracy
• Coordination
• Installation requirements
• Compliance with approved materials
• Relevant contractual obligations

Likewise, shop drawing approval should not be used to introduce unauthorized changes to the original design.

Any significant departure from the IFC documents should be clearly identified and approved through the appropriate technical process.

Shop Drawings in Structural Steel Projects

Structural steel is one of the clearest examples of why shop drawings are essential.

The IFC structural design may define:

• Member sizes
• Structural loads
• General connections
• Grid locations
• Building geometry

Fabrication drawings then provide detailed information required by the steel workshop.

These may include:

• Cutting dimensions
• Bolt holes
• Welds
• Plates
• Stiffeners
• Connection details
• Piece marks
• Assembly references

Erection drawings may also show where each fabricated member should be installed on site.

Errors at this stage can affect both fabrication and erection, which is why detailed review is essential.

Shop Drawings in MEP Projects

MEP shop drawings focus heavily on coordination.

For example, plumbing shop drawings may define:

• Pipe routes
• Diameters
• Slopes
• Invert levels
• Valves
• Supports
• Access locations

Electrical shop drawings may include:

• Cable tray routes
• Conduit routing
• Equipment layouts
• Panel locations
• Connection details

HVAC shop drawings may show:

• Duct routing
• Equipment locations
• Grilles
• Diffusers
• Supports
• Levels
• Maintenance clearances

These systems must be coordinated with structural and architectural elements before installation begins.

Why Revision Control Matters

Projects constantly generate revised drawings.

The design team may issue a new IFC revision while shop drawings are already under preparation.

If the contractor continues using an outdated revision, the result can be serious.

Possible consequences include:

• Incorrect fabrication
• Wrong openings
• Material waste
• Rework
• Delays
• Commercial disputes

A proper document control system should therefore track:

• Drawing number
• Revision
• Issue date
• Approval status
• Distribution
• Superseded versions

Only the latest approved drawing should be available to site teams.

What Should Project Owners Check?

Project owners do not need to review every fabrication detail personally, but they should ensure that the project has a controlled drawing workflow.

Key questions include:

• Has the complete IFC package been issued?
• Are all disciplines coordinated?
• Is there a shop drawing schedule?
• Are critical drawings being prioritized?
• Are consultant comments tracked?
• Are approved drawings reaching the site?
• Are obsolete revisions being removed?
• Are changes reflected across affected disciplines?

These controls are particularly important on fast-track projects where design, procurement, fabrication, and construction may overlap.

Common Shop Drawing Problems

Copying IFC Drawings Without Adding Execution Detail

A shop drawing should provide practical construction information.

Simply reproducing the design drawing provides little value.

Submitting Uncoordinated Drawings

A technically correct HVAC drawing may still be impossible to install if it conflicts with structural or electrical work.

Starting Fabrication Before Approval

This can lead to expensive material waste if changes are later required.

Ignoring Consultant Comments

Approval comments should be incorporated before the drawing is released for site use.

Using Outdated IFC Revisions

Shop drawings should always be based on the current approved design documents.

How Skilya Coordinates IFC and Shop Drawings Across Construction Disciplines

Skilya works across multiple construction disciplines, including general contracting, civil construction, structural steel, MEP systems, infrastructure, finishing works, and industrial project execution.

Because these scopes frequently interact, drawing coordination is an important part of Skilya’s project delivery approach.

During execution, Skilya can review IFC requirements alongside the practical needs of construction teams, specialist subcontractors, steel fabrication activities, MEP installations, and site conditions.

For structural steel work, detailed shop drawings help translate engineering requirements into fabrication and erection information. For MEP activities, coordinated drawings help organize ductwork, piping, cable routes, equipment, supports, and access requirements around the architectural and structural design.

Through its integrated general contracting services, Skilya can also coordinate interfaces between different disciplines before work reaches the installation stage.

This helps reduce situations where one trade completes work that later needs to be modified to accommodate another.

For industrial, commercial, and complex building projects, this drawing coordination supports more accurate fabrication, clearer construction sequencing, better communication between project parties, and lower risk of avoidable rework.

How IFC Drawings, Shop Drawings, and RFIs Work Together

These three processes are closely connected.

The sequence often works as follows:

IFC Drawing → Contractor Review → RFI if Required → Technical Clarification → Shop Drawing → Approval → Construction

This workflow allows technical uncertainty to be resolved before installation.

Skipping one of these steps can increase project risk.

For example, creating a shop drawing based on unclear IFC information without raising an RFI may result in the contractor introducing an unapproved assumption.

Final Thoughts

The difference between shop drawings vs IFC drawings is not simply a difference in drawing format.

They perform two different functions within construction delivery.

IFC drawings define the approved design requirements.

Shop drawings translate those requirements into detailed fabrication and installation information.

When both are properly prepared, reviewed, coordinated, approved, and controlled, they help construction teams identify clashes before work begins and reduce the risk of incorrect installation.

For project owners, a strong drawing management process provides greater confidence that what is being fabricated and constructed on site remains aligned with the approved project design.