FAQ

Metal Building Systems

What is a Metal Building System?

Metal building systems today are a far cry from their origins many years ago. To see a detailed description of custom-engineered metal building systems as well as the MBMA's and its members' roles in the process, please click here.


Metal building system manufacturers, that are members of MBMA, have developed a proprietary building system, have professional engineers on staff, have manufacturing plant facilities and are accredited under the International Accreditation Services' third-party accreditation program for metal building systems.


All MBMA member companies are accredited through the IAS AC472 accreditation program.


To see a wide array of examples of high quality, custom-engineered metal buildings, click here to go to the photo gallery.

Where do I find information relative to statistics, forecast reports and trends?

The Industry Trends page of our web site provides current and historical information on this subject.

I need to specify a metal building. Is there a guideline specification that I can use to help me?

Yes. MBMA has published a Guide Specification which you can download by clicking the button below. It identifies various provisions, which should be addressed and allows the user to insert critical parameters. These specifications are free and available as a PDF or Word document via the MBMA bookstore. Click on the link below to open the Metal Building Guide Specifications page and to review the specification in its entirety.

Metal Building Guide Specifications

Who is responsible for the design of the foundation of a metal building project?

The responsibility for foundation design is addressed in the Common Industry Practices Section of the Metal Building Systems Manual, unless altered by the specific agreement between the parties. The Manufacturer is not responsible for the design, materials, and workmanship of the foundation. Anchor bolt plans prepared by the Manufacturer are intended to show only the location and diameter of anchor bolts required to attach the Metal Building System to the foundation. The Manufacturer is responsible for providing to the Builder the loads imposed by the Metal Building System on the foundation. It is the responsibility of the Owner to ensure that adequate provisions are made for the connections between the metal building and the concrete foundation, as well as foundation design.

Does MBMA establish erection tolerances for metal buildings? If so, what are they?

Erection tolerances are those set forth in the AISC Code of Standard Practice, available as a free download from the AISC website, www.aisc.org. When crane support systems are part of the metal building system, additional erection tolerances are specified in Section 6 of the Common Industry Practices, contained in the MBMA Metal Building Systems Manual.

Does MBMA publish a standard that establishes practices relating to the design, manufacture, sale and erection of metal building systems?

In the MBMA Metal Building Systems Manual, Chapter IV contains Common Industry Practices. This is not intended as a standard or as a specific guideline for the design, manufacture, sale or erection of any particular metal building system. Rather, it is intended to serve as a general checklist to assist parties in preparing specific order or contract documents governing a particular application. If the parties so desire, these Common Industry Practices can be incorporated by reference, in whole or in part, into the order or contract documents for the sale of a metal building system.

Primary and Secondary Structural Systems

Why do some roofs have more purlin braces than others? What are the requirements for bracing purlins, especially with standing seam roofs?

For more information on the "Base Test" and purlin bracing with standing seam roofs, see AISI Design Guide D111-09.

What are the limitations on allowable drift (sidesway) in metal buildings?

This topic is addressed in the AISC's Steel Design Guide Series No. 3: Serviceability Design Considerations for Low-Rise Buildings, available from the AISC website (www.aisc.org), as well as in Chapter 3 of the MBMA Metal Building Systems Manual. The limitations for drift vary, depending on the type of material attached to the framing and the tolerance for movement. For example, for metal panels attached to framing, the recommended maximum drift is between H/60 and H/100 where H is the building height. It is also recommended that the wind load used to compute the drift when checking against these allowable limits should be based on a 10 year recurrence interval, which is approximately equal to 75% of the normal 50 year design wind pressure. For other types of cladding, refer to the references cited for more discussion.

Does MBMA establish erection tolerances for metal buildings? If so, what are they?

Erection tolerances are addressed in the Common Industry Practices Section of the MBMA Metal Building Systems Manual. Erection tolerances are those set forth in the AISC Code of Standard Practice, available as a free download from the AISC website, www.aisc.org. When crane support systems are part of the metal building system, additional erection tolerances are specified in Section 6 of the Common Industry Practices, found in the MBMA Metal Building Systems Manual.

Metal Roof and Wall Systems

Where can I get information on designing a standing seam roof?

MBMA published the Metal Roofing Systems Design Manual (most recent in 2012) - a one-of-a-kind design and detail manual for architects, manufacturers, engineers, specifiers, builders and others involved in the metal roofing industry. The manual can be purchased here. In addition AISI has published D111-09 - Design Guide for Cold-Formed Steel Purlin Roof Framing Systems. The development of this guide was co-sponsored by MBMA and AISI. The guide is available through AISI by calling 1-800-277-3850.

Metal Roofing Systems Design Manual

In addition AISI has published "A Guide for Designing With Standing Seam Roof Panels", Design Guide CF97-1. The development of this guide was co-sponsored by MBMA and AISI. The guide is available through AISI by calling 1-800-277-3850.

Metal Roofing Systems Design Manual

I need to specify a metal roofing system. Is there a guideline specification that I can use to help?

Yes. MBMA has the Metal Roofing System Guide Specification intended for use on projects where the Structural Standing Seam Roof System (SSSRS) is supplied as an item separate from the building's structural system. There are a number of provisions in the specification which are not appropriate for roofing systems supplied as part of a complete building system. Roof systems supplied with a metal building system should be referred to the Metal Building Manufacturers Association Guide Specification for Metal Building Systems. These specifications are free and available as a PDF or Word document via the MBMA bookstore. Click on the link below to open the Roofing Guide Specifications page and to review the specification in its entirety.

Metal Building Systems Manual

What is " Galvalume" versus galvanized steel?

Various metallic coatings for steel sheets are available for use in the metal building industry. These coatings are either zinc, aluminum, or an aluminum-zinc alloy. The aluminum-zinc alloys are referred to by the percent of aluminum present in the coating by weight. Galvalume is a trademark for a steel roofing product that is 55% Aluminum-Zinc alloy coated. It is also manufactured and sold under the trademark Zincalume. Trademark for a steel roofing product that is 55% Aluminum-Zinc alloy coated. It is also manufactured and sold under the trademark Zincalume.

ASTM A792 is the specification covering sheet steel coated by this process. The coating designation refers to the weight, e.g. AZ55 is 0.55 oz/ft2, total for both sides. Galvanized products, on the other hand, utilize a zinc coating. ASTM A653 is the specification covering galvanized steel sheets. The coating designation for galvanized products also refers to the weight, e.g. G90 is 0.90 oz/ft2, total for both sides. Aluminum-coated steel sheet is covered by ASTM A463. General requirements for all of the steel sheet products that are metallic-coated by the hot-dip process are covered in ASTM A924. Your metal building manufacturer/builder can help determine which metallic-coated product is best suited for your application. Additional information can also be obtained from the Galvalume Sheet Producers of North America.

Accreditation

What does Accreditation mean for me?

MBMA has created a series of informational flyers to educate building officials, owners, contractors, customers and specifiers about AC472 Accreditation. Click on the title below to see more information.

Why is it important to use an MBMA member firm on my next project?

MBMA members construct 95% of all metal building systems built in the United States. Working through the MBMA, member companies are actively engaged in the association's research and engineering programs, insurance work, manufacturing standards, and construction activities. Members are also kept up-to-date on the latest codes, standards and common industry practices through the association. By using an MBMA member firm on your next project, you will benefit from the qualifications and expertise that is necessary for membership in MBMA.

Members and Membership

What are the qualifications for MBMA membership?

MBMA is an Association comprised of metal building system manufacturers and also suppliers who fabricate or manufacture materials for individual member companies.


To become a metal building system manufacturer member:

  • The company must be engaged in the design, manufacture and sale of metal building systems within the United States for at least two years.
  • They must employ a licensed professional engineer who supervises the design and drafting activities.
  • They must employ detailers and draftsmen to process orders. The firm must produce a substantial majority of the basic elements (in total) of the metal building system.
  • They must be accredited under the IAS AC472 program.

Who are the members of MBMA?

MBMA has two categories of membership.


  • Building Systems Manufacturers, who design, engineer, fabricate and market metal building systems. These members are also required to be IAS AC472 accredited.
  • Associate Members, who consist of suppliers of products or services used by Building Systems Manufacturers.

To see a listing of MBMA members and to learn more about them click here.

Fire Codes and Rated Assemblies

Where can I obtain information on fire ratings for metal building systems?

MBMA and AISI (American Iron and Steel Institute) have conducted tests at Underwriters Laboratory for various wall and roof assemblies. These designs can be found in the UL Fire Resistance Directory and the MBMA Metal Building Systems Manual. You can find fire ratings in the Fire Resistance section of this site, and additional insurance information in the Building Insurance section of the site.

I have been told that my building must meet Factory Mutual requirements. What are these and why does Factory Mutual have special requirements?

Some insurance companies, including Factory Mutual (FM), have their own structural design requirements that often exceed the local building code requirements. MBMA has worked closely with FM and other insurance companies to make sure there is a clear understanding of what their requirements are, and to try to utilize nationally recognized consensus standards where possible. It is important that these insurance requirements are discussed early in the planning and design stage as they may have significant impact on the building design. The building manufacturer can design the building to any additional requirements over and above the local building codes, but this must be communicated to the manufacturer/builder. The reason some insurance companies have their own special requirements is simple. Building codes are based on designing structures to withstand loads that may occur once in 50 years. To minimize their losses following natural disasters, insurance companies may require structures to withstand loads that may occur once in 100 years.

Sustainability and Energy

I need a building that can satisfy various energy codes and standards. Can metal building systems comply with energy standards and programs?

Yes. Metal building systems are very energy efficient and there are different ways to comply with the requirements of ASHRAE 90.1. Your builder should be able to help with these requirements. Additionally, the MBMA Energy Design Guide for Metal Building Systems contains information on how to meet various energy codes and standards. The North American Insulation Manufacturers Association (NAIMA) also has prescriptive systems for complying with ASHRAE 90.1 in their publication, "ASHRAE 90.1 Compliance for Metal Buildings."

Does MBMA have any information on condensation and ways to control it?

MBMA has published a booklet called the Condensation Fact Sheet that provides answers for some of the questions concerning condensation such as: what is condensation; what causes condensation; how is it best controlled? Click on the link below to view the complete Condensation Fact Sheet.

PDF Download: MBMA Condensation Facts

Building Insurance

What are the factors affecting insurance rates of metal buildings?

Metal building rates or loss costs can vary up or down and can even be classified in a different construction type than Class 3, noncombustible, depending upon some of the features you may incorporate into the building. The following are some factors that should be considered.
  • Use of resistive approved materials on columns and other structural elements.
  • Use of a combustible insulation or combustible interior finish material.
  • Installation of automatic sprinkler systems.

Does MBMA have information on metal building insurance?

MBMA has compiled a significant amount of information on insurance, rate setting, comparisons of metal buildings systems to ordinary construction, how to work with insurance underwriters and state insurance agencies, and other forms of insurance coverage. Click here to investigate this information.

Industry Associations & Affiliated Organizations

Below is a list of MBMA-affiliated organizations with links to their web sites. Click on the web site addresses on the right to open to the webpage of that organization in another window.

Affiliated Organizations Click Here ...
American Institute of Architects (AIA) www.aia.org
American Institute of Steel Construction (AISC) www.aisc.org
American Iron and Steel Institute (AISI) www.steel.org
American Society of Civil Engineers (ASCE) www.asce.org
American Welding Society (AWS) www.amweld.org
Cold Formed Steel Engineers Institute (CFSEI) www.cfsei.org
Construction Specification Institute (CSI) www.csinet.org
Galvalume Sheet Producers (GSP) www.steelroofing.com
Gypsum Association (GA) www.gypsum.org
North American Insulation Manufacturer's Association (NAIMA) www.naima.org
National Coil Coating Association (NCCA) www.coilcoating.org
National Fire Protection Association (NFPA) www.nfpa.org
National Insulation Association (NIA) www.insulation.org
National Institute of Building Sciences (NIBS) www.nibs.org
National Roofing Contractors Association (NRCA) www.nrca.net


Codes, Standards and Other Organizations Click Here ...
American Society For Testing And Materials (ASTM) www.astm.org
American Society For Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) www.ashrae.org
Building Officials and Code Administrators (BOCA) www.bocai.org
Systems Builders Association (SBA) www.systemsbuilders.org
Metal Building Contractors & Erectors Association (MBCEA) www.mbcea.org
International Code Council (ICC) www.iccsafe.org
International Council of Building Officials (ICBO) - now part of the International Code Council (ICC) www.icbo.org
South Florida Building Code (SFBC) www.buildingcodeonline.com
Underwriter's Laboratories (UL) www.ul.com
Factory Mutual Engineering and Research (FM) www.fmglobal.com
American National Standards Institute (ANSI) www.ansi.org
National Institute of Standards and Technology (NIST) www.nist.gov