Pre-engineered metal buildings are one of the most common commercial and industrial building types in the United States, but many buyers are surprised to learn that the foundation engineering is not included with the building package. The manufacturer engineers the steel superstructure, but a local PE must design the foundation separately. Our new building structural engineering team designs PEMB foundations for contractors across all 50 states.
The Split Responsibility in PEMB Projects
Pre-engineered metal building manufacturers engineer the steel frame, roof panels, wall panels, and all primary structural members. Their engineers size the columns, rafters, and bracing for the specified loads and produce anchor bolt plans and reaction forces at each column base. However, the manufacturer’s engineering stops at the foundation top surface. Everything below that point is the local PE’s responsibility.
This division of engineering responsibility is standard practice in the metal building industry and is acknowledged in the manufacturer’s documents. The manufacturer’s drawings and calculations cover the superstructure above the anchor bolts, and the local PE’s drawings cover the foundation, anchorage, and any other site-specific structural work such as concrete slabs and grade beams.
Contractors sometimes assume the manufacturer’s package includes foundation engineering because the package is so comprehensive for everything else. This misunderstanding can cause significant schedule delays when the permit stage arrives and the building department requests foundation drawings stamped by a local PE. Our structural engineering team can be engaged early in the process to avoid this delay.
What the Manufacturer Provides
The manufacturer provides an anchor bolt plan showing the location and size of all anchor bolts at each column line, along with the column base plate dimensions. They also provide a reactions table listing the vertical load, horizontal shear, and overturning moment at each column base for each governing load combination. These reactions are the primary input to the local PE’s foundation design.
The manufacturer may also provide a general foundation design guide, but this guide is not a substitute for site-specific engineering. The guide typically describes foundation types used with that manufacturer’s buildings but does not account for local soil conditions, frost depth, seismic zone, or wind exposure at the specific project site.
What the Local PE Must Design
Column Footings
Each column base receives a spread footing sized to distribute the column load over enough soil area to stay within the allowable bearing capacity. Footing size depends on the column load from the manufacturer’s reactions and on the soil bearing capacity from a geotechnical report or from local geotechnical assumptions. In poor soil conditions, deep footings or piers may be required to reach competent bearing material.
Grade Beams
Most PEMB foundations include grade beams connecting the column footings around the building perimeter. Grade beams provide lateral restraint between column bases under seismic and wind loads, distribute loads more evenly, and provide a surface for the wall panel base connections. The grade beam must be designed for the lateral thrust from the column bases under all governing load combinations. For facilities requiring specialty structural solutions, grade beams may also support mezzanines or other equipment.
Slab on Grade
The interior concrete slab is typically designed separately from the foundation but is part of the local PE’s scope. Slab design depends on the floor loads (storage, equipment, vehicles), the subgrade conditions, and any special requirements such as floor flatness tolerances for racking systems or loading dock transitions.
Anchor Bolt Embedment
The local PE must verify that the anchor bolt embedment into the concrete footing or grade beam is sufficient to develop the required tension and shear capacity. Anchor bolt design follows ACI 318 Chapter 17 for concrete anchorage and must match the manufacturer’s specified anchor bolt size, pattern, and projection above the slab.
Jurisdiction Requirements for PEMB Foundation Engineering
Most jurisdictions require a local PE to stamp the foundation drawings for any commercial building, including PEMB projects. Some jurisdictions specifically require that the local PE be licensed in their state and be familiar with local soil and seismic conditions. Submitting only the manufacturer’s stamped superstructure drawings without local PE foundation drawings will result in permit rejection in virtually every commercial jurisdiction. Our engineering process includes jurisdiction-specific review before we submit.
Common Red Flags in PEMB Projects
Red flags that indicate foundation engineering may be inadequate or missing: no anchor bolt plan from the manufacturer (the PE cannot design footings without knowing anchor bolt locations and loads); manufacturer reactions shown without breakdown by load case (the PE needs separate reactions for dead, live, wind, and seismic loads to properly design for each combination); foundation design from another state used without modification for the new location (frost depth, seismic zone, wind speed, and soil conditions all vary by location and must be reflected in the foundation design).
Frequently Asked Questions
Can I use the manufacturer’s foundation guide instead of hiring a local PE?
No. The manufacturer’s foundation guide is a general reference document, not site-specific engineering. Most jurisdictions will not accept it as a substitute for locally stamped foundation drawings. The manufacturer’s guide explicitly states that it is not a substitute for engineering by a licensed professional.
How early in the PEMB procurement process should I engage the foundation PE?
Ideally, the foundation PE is engaged when the building is being priced, before the purchase order is placed. The PE can identify any site-specific foundation requirements that might affect the cost and can request the anchor bolt plan from the manufacturer as soon as the building layout is finalized. Engaging the PE late in the process risks schedule delays at the permit stage.
Does the local PE need to coordinate with the manufacturer?
Yes. The local PE needs the manufacturer’s anchor bolt plan, reactions table, and base plate dimensions. These are typically provided in the erection drawings and design calculations package. For unusual conditions such as very high seismic or wind loads, the local PE may need to contact the manufacturer’s engineer to clarify specific reaction values or load combinations.
Start Your PEMB Foundation Design
We design PEMB foundations for contractors and developers in all 50 states. Submit your project at rightangleeng.com/get-started with the manufacturer’s anchor bolt plan and reactions table.
References
Metal Building Manufacturers Association. (2023). MBMA Metal Building Systems Manual. Cleveland, OH.
American Concrete Institute. (2019). ACI 318-19: Building Code Requirements for Structural Concrete. Chapter 17: Anchoring to Concrete.
American Institute of Steel Construction. (2022). Steel Construction Manual. Chapter on column base plates and anchor rods.