1 August 1998
order an entire building (frame, wall, and roof covering) or parts (frame and roof). Parts may be
combined with other building materials (masonry, precast concrete, light gauge steel framing and siding,
etc.) To provide a complete facility. Low cost and speed of fabrication/erection are the principal
advantages to using a Metal Building System type structure. Manufacturers that specialize in this work
have developed design and fabrication techniques that make them very competitive. The perception
that these buildings are inferior to other custom designed structures comes primarily from early industry
reliance on a separate building code (MBMA Low Rise Building Systems Manual), which at one time did
promote the use of wind and live load pressures that were less than those traditionally used. (It should
be noted that the MBMA supported their criteria with tests indicating that traditional criteria was too
conservative for low rise single story structures.) Recent changes sin both the MBMA design guidelines
and the traditional codes have rought the two closer together so that today, the differences are small.
Owners who express a concern for structural suitability should be counseled on the specific differences,
if any. Persistent concerns can be resolved by requiring the manufacturer to design to the higher code
requirement since almost any reasonable requirement can be accommodated by the manufacturer.
d. Corps Guide Specifications. Metal Building Systems are obtained by the Corps of Engineers
using either of two performance specifications: CEGS 13120, Metal Building Systems or CEGS 13121,
Metal Building Systems (Minor Requirements). Projects that include buildings supplied under both specs
should specify which specification applies to which building.
\The first specification is used for medium
to large structures./1/ CEGS 13120 should be used for most COD projects where an occupied structure
is proposed. The specifying engineer will edit the specification and define the owner's requirements to
include the design codes to be used. Do not leave both options in the specification or mix options since
this complicates the design.
\CEGS 13121 was developed for small, simple commercial products./1/
Examples are pump houses, small storage building, guard house, small maintenance shops, etc. More
complex projects, those that use masonry, contain cranes, have other special design requirements, or
contain high dollar value contents should use CEGS 13120.
e. Foundations. Metal Building System manufacturers do not design foundations; foundation
investigation and design is performed by the contractor. The manufacturer provides column reactions for
the specified loading, and the building contractor obtains the services of a professional engineer to
design the site-specific foundations for the delivered structure using the reactions and a foundation
report. On Corps of Engineers projects, using CEGS 13120, the Corps performs a preliminary design fo
the foundations based on the data obtained from in-house or AE-prepared engineering analysis of a
typical structure, or from the Metal Building manufacturer based on its analysis of the proposed structure.
The resulting foundation design is shown on the drawings as both a basis for bid by the contractor, and to
identify foundation type and typical details required for the final foundation design. The final design is
performed by a registered professional engineer hired by the contractor. The soils data used for the
design is included in the Corps specification. Final column reactions are supplied by the Metal Building
manufacturer who will provide the building. Corps of Engineers projects that use CEGS 13121 to not
include a preliminary design. Complete design is performed by the contractor.
f. Other Foundations (Non-metal Building Systems Manufacturer Supplied Items). Foundations for
all Non-metal Building System supplied items, such as masonry wall and equipment foundations, should
be designed by the project structural engineer and shown on the contract drawings. Design responsibility
should not be transferred to the contractor or to his (or her) foundations engineer.
g. Design Criteria. As previously discussed, MBMA publishes a design manual, "Low Rise Building
Systems Manual," that establishes standard design and commercial practices for metal buildings.
Compliance with this manual (code) is voluntary, but most commercial structures provided by MBMA
members follow this guidance. Manufacturers can, and do, design to other national and local codes
when requested by the owner. Metal Buildings were first used for farm, warehouse, and other utilitarian