Pre-engineered steel buildings show up on a lot of self storage sites, and for good reason. They arrive as a designed package, go up quickly, and suit the long, repetitive layouts that self storage uses. But a pre-engineered metal building is not the whole structure, and it is not the right answer for every project. This guide from Metal Engineers LLC, a structural engineering firm for steel buildings and multi-story self storage, explains how pre-engineered steel buildings work on self storage projects, where they fit, and where the structural engineer comes in.
What a Pre-Engineered Steel Building Is
A pre-engineered metal building is a steel building system designed and supplied by a manufacturer. The package typically includes the main steel frames, the secondary framing that supports the walls and roof, and the wall and roof panels. The manufacturer designs these parts for the loads specified for the project and supplies drawings for them.
Conventional structural steel works differently. Beams and columns are designed for the specific building by the project's structural engineer and then fabricated to those drawings. Both approaches use steel. The difference is who designs which parts, and how flexible the system is.
Where Pre-Engineered Steel Buildings Fit in Self Storage
Pre-engineered steel buildings are a natural match for many self storage layouts:
Single-story drive-up buildings. Long, narrow buildings with repeating unit doors suit a pre-engineered frame well.
Single-story interior buildings. Climate-controlled buildings with interior hallways often use a pre-engineered shell around the unit partitions.
Repeatable site plans. Sites with several similar buildings benefit from a system designed once and repeated.
Multi-story self storage is different. Elevated floors carrying stored goods, elevator and stair openings, and heavier foundations often call for conventional structural steel, or a combination of a pre-engineered roof system with a conventionally designed structure below. The deciding factors are height, spans, and loads, which is why the framing choice belongs in the earliest design conversations. The Metal Engineers LLC guide on the cost to build multi-story self storage covers how that choice affects the budget.
What the Manufacturer Designs and What It Does Not
A common surprise for developers is that the pre-engineered building package leaves parts of the structure to someone else. The manufacturer designs its own components. Several other pieces still need engineering:
Foundations. The manufacturer provides the forces its frames put on the foundation. The footings, slab, and anchorage that resist those forces are designed separately, using the site's geotechnical report.
Elevated floors and mezzanines. Upper floors inside or alongside the building are typically designed outside the manufacturer's package.
Elevator and stair structures. Shafts, stair framing, and their openings need their own design and coordination.
Connections to other structures. Where the metal building meets an office, a conventional steel section, or an existing building, the interface needs engineering.
Site-specific review. Someone has to confirm the loads the manufacturer designed for match the building code requirements for the actual site.
Leaving any of these unassigned is how projects lose time in permitting. Settling who designs each piece at the start keeps the drawings complete.
Pre-Engineered Metal Building Drawings and Permitting
A permit submittal for a self storage building with a pre-engineered metal building usually includes two sets of structural documents: the manufacturer's drawings and calculations for its building system, and the project structural drawings for foundations and everything outside the package. The building department reviews both.
When the two sets are coordinated, review moves faster. When the foundation design does not match the manufacturer's reactions, or an elevated floor is not shown anywhere, reviewers send comments back and the schedule slips. Coordinating those documents is a core part of the structural engineer's job, as described in the guide to what a self storage structural engineer does.
Pre-Engineered vs Conventional Steel: The Trade-Offs
Speed. A pre-engineered package is designed and supplied as a system, which can shorten the time from order to erection on simple buildings.
Flexibility. Conventional structural steel is designed around the specific building, which gives more freedom for elevated floors, large openings, and unusual layouts.
Coordination. A pre-engineered building splits the design between the manufacturer and the project engineer, so the two sets of drawings have to be coordinated. Conventional steel keeps the frame design with one engineer.
Questions to Ask Before Choosing a Framing System
How many stories will the building have, now and in any future phase?
Will there be elevated floors, elevators, or mezzanines?
What spans does the unit layout need between columns?
What wind and snow requirements apply at the site?
Who will design the foundations and any structure outside the manufacturer's package?
The answers usually point clearly toward a pre-engineered system, conventional steel, or a combination.
Working With Metal Engineers LLC
Metal Engineers LLC provides structural engineering for steel buildings and self storage, with multi-story self storage as its lead service. The firm's licensed structural engineers each bring 12 to 27 years of experience. Based in Georgia, Metal Engineers LLC is registered in 34 states, including Georgia, Florida, Texas, and Tennessee.
Metal Engineers LLC designs the structure. The building is supplied and built by others. To talk through a project, contact Metal Engineers LLC or see recent projects.
Frequently Asked Questions
What is a pre-engineered steel building?
It is a steel building system designed and supplied by a manufacturer, typically including the main frames, secondary framing, and wall and roof panels. The manufacturer designs those components for the loads specified for the project.
Are pre-engineered steel buildings good for self storage?
They are a common choice for single-story self storage, both drive-up and interior. Multi-story buildings with elevated floors and elevators often need conventional structural steel or a combination of systems.
Do I still need a structural engineer with a pre-engineered metal building?
In most cases, yes. Foundations, elevated floors, elevator and stair structures, and connections to other structures are typically designed outside the manufacturer's package.
What drawings are needed to permit a pre-engineered metal building?
Usually the manufacturer's building drawings and calculations plus project structural drawings for the foundations and any structure outside the package. Requirements vary by building department.
Can a multi-story self storage building use a pre-engineered system?
Sometimes, often in combination with conventional steel below a pre-engineered roof. Height, spans, and floor loads decide it, which is why the framing system should be chosen early.