Avoid Premature Failure of Your Hollow Metal Doors and Frames

Steel is strong. But you need to specify the correct type of steel to ensure your doors and frames perform to their potential. The use of galvannealed coatings on carbon steel sheets can make a major difference in extending the life of doors and frames that are exposed to moisture.

Moisture can get on the exterior surface or inside of a door or frame in several ways:

  • From the top, for example when rain water runs down the side of the building;
  • From the bottom, if there is flooding;
  • Through the hinge and lock preps, with water sprayed from a sprinkler.

Many specifications only call for cold rolled steel doors with factory-applied primer, however this type of coating only protects the outside surface of the door. The raw, uncoated cold rolled material on the inside of the hollow metal door remains unprotected, resulting in the door rusting from the inside out. Galvannealing, used in conjunction with a rust inhibitive factory primer results in a very durable finish.

The iron-zinc coating created in the galvannealing process protects the steel by:

  1. Acting as a barrier between the steel and the environment;
  2. Sacrificing itself if galvanic corrosion occurs.

The iron-zinc coating thickness determines how long protection will be provided, although thicker coatings may result in reduced paint adhesion. The Steel Door Institute recommends A40 and A60 coatings, as a minimum. The heavier A60 coating is recommended for openings where rust is a concern. See SDI 112 (Zinc-Coated Steel Doors and Frames) for more information.

Prevent premature corrosion of your exterior doors and frames by specifying a galvannealed coating. Your clients will be glad you did.

New SDI Videos

Why Steel?

SDI has just released a new video demonstrating the superior strength, longevity, and specialty performance of steel.This video is based on the performance study Why Steel?, which uses industry data to compare the abilities of steel, wood, aluminum and fiberglass doors.


Specialty steel doors are the only doors that meet storm shelter standards and can hold up against tornado-strength winds and flying debris. Take a look at our new video that demonstrates the kind of punishment specialty steel doors can take and still keep the people on the inside safe and sound.

Hollow Metal Xpress Joins SDI

green HMX logo

Hollow Metal Xpress (HMX) is the newest manufacturer to join the Steel Door Institute’s select membership, increasing SDI’s membership to 12 manufacturers.

The approval process included an onsite audit by steel door and frame engineers that certified HMX as meeting SDI’s rigorous standards. Based in Phoenix, AZ, HMX has roots in manufacturing hollow metal doors and frames manufacturing that go back 25 years. “We created our Project Services division in 2011 to compliment and add to the quick-ship services our company was founded upon,” said Steve Gay, Vice President and General Manager of HMX. “Joining an elite organization like SDI was the natural next step in our company’s development.”