Roofing was one of the first building applications for stainless steel. One US industrial roof was reportedly installed in 1924. The building is still in use and the maintenance department is not aware of any repairs. Industrial roofing remains a large and cost effective application for stainless steel.  A leaking roof can shut down a production line, which is very expensive. Stainless steel  is used when there are particularly corrosive plant or environmental conditions.

The first large high-profile roof was installed in 1930 on the Chrysler Building in New York. Stainless steel roofing remains a very popular choice for high visibility buildings because of its resistance to high wind loading, hail, fire and corrosion.  While other steels can also withstand high winds and hail when new, they can be weakened by corrosion over time.

Stainless steel roof finishes can meet both strict aviation low-reflectivity and solar reflective index (SRI) requirements. When properly selected for the environment, the SRI values of uncoated stainless steel do not deteriorate over time, because there is no corrosion to change the finish. At most, occasional dirt removal maybe required.  It has been used for airport, museum, residential, university, government and many other building types.

Finishes
The mill-applied 2B and rolled-on dull matt finishes are the most commonly-used options for roofing. Electrochemically coloring over a dull finish, paint and various metallic coatings (i.e. tin/zinc, tin, and copper) are also widely used on stainless steel. With the exception of electrochemically coloring, which is applied to smaller panels, these finishes can be used for any roof style.

Roof aesthetic preferences and airport corridor roof reflectivity limits vary around the world. The 2B finish is the most reflective of these common options and any panel waviness from fabrication or thermal expansion will be more visible. In the Americas, that appearance is usually considered aesthetically undesirable and 2B use is typically limited to industrial or canopy roofs. In Europe and South Africa, waviness can be associated with a “handmade” roof and 2B is used on higher end buildings. It will not meet airport landing corridor reflectivity limitations in many parts of the world.

Gutters, flashing, downspouts, parapet coping and other smaller roofing system components typically have a 2B finish because it is the least expensive option that is readily available in light gauges.

The commonly used 2D mill-produced finish has been replaced by the less reflective rolled-on dull matt products developed for roofing in most markets.  It is now difficult to obtain 2D in the light gauges used for roofing.

Design Resources

• SMACNA Architectural Sheet Metal Manual
  Although this is not a free publication, it is the most comprehensive manual available on the proper design of non-proprietary, custom-fabricated, architectural sheet metal roofs, roof elements, and drainage systems. It includes metal thickness comparison.
• SSINA Designer Handbook: Standard Practices for Stainless Steel Roofing, Flashing, Copings
  This free US brochure contains standard practices, gauge guidance and drawings for stainless steel roofing panels, flashings, and drainage systems.
• JSSA/Nickel Institute Design and Construction of Roofs of Stainless Steel Sheet (12006)
  This is a free English translation of a comprehensive Japanese brochure on stainless steel roof and drainage system design with detailed drawings.

Download a free Stainless Steel Library (zip file, 559 MB) with over 360 pdfs covering building and construction applications, selection, specification, fabrication, sustainability and other common questions.

For previous issues or to subscibe to the e-newsletter, please visit the archive page.

IMOA is an AIA continuing education system approved provider with eight 1-hour programs that are registered for both live face-to-face and distance learning credit.

1. Stainless Steel Sustainable Design
2. Bioclimatic Design With Stainless Steel Weather Screens
3. Stainless Steel Structural Design
4. Stainless Steel Specification For Corrosive Applications
5. Deicing Salt: Stainless Steel Selection to Avoid Corrosion
6. Stainless Steel Finish Specification
7. Advanced Stainless Steel Specification and Problem Avoidance
8. Specification of Stainless Steel Finishes and Grades For Corrosive Applications

For more information or to schedule a workshop contact Catherine Houska, 412-369-0377 or email chouska@tmr-inc.com.

IMOA (International Molybdenum Association) is a non-profit industry association, which provides technical information to assist with successful specification of molybdenum-containing materials. Molybdenum is an element. When it is added to stainless steel, molybdenum increases its resistance to corrosion caused by deicing salts, coastal atmosphere and pollution.

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In providing consultation or other assistance with respect to technical issues, any consultation, assistance or material is provided for the general information of the recipient and should not be used or relied upon for any specific application without first securing competent advice. IMOA and their respective employees, consultants and members (i) make no representation or warranty, express or implied, of any kind with regard to such consultation, assistance or material including no representation or warranty of  suitability for any general or specific use; (ii) assume no liability or responsibility of any kind in connection  therewith; and (iii) disclaim any and all liability for any claim that arises therefrom.