Hollow metal frames are shaped from flat steel sheets of different thicknesses to form what is called a “profile”. Depending on the manufacturer, there are many profiles that can be formed. For most openings, however, there are a set of common hollow metal frame profiles that can be used.

What are they and what are their applications?

These are the 4 most common hollow metal frame profiles:

  1. Single Rabbet
  2. Double Rabbet
  3. Double Egress
  4. Cased Opening

1. Single Rabbet Profile

 

A single rabbet hollow metal frame profile gets its name from the fact that the frame only has one single rabbet (to learn what a “rabbet” is, read our previous blog post on hollow metal frame terminology). The rabbet will receive the door. Single rabbet frames are usually required on openings where the wall thickness is 3-1/2″ or less in depth overall. A single rabbet can be used for wall thickness above 3-1/2″ in depth and can be specified when aesthetics are a concern.

2. Double Rabbet Profile

 

Double rabbet profiles are the most common hollow metal frame profile that is used. The double rabbet hollow metal frame profile also gets its name from the fact that the frame has two rabbets. These rabbets can be specified as equal or unequal in dimension.

The rabbet size dimensions are determined by the door thickness that is to be used in each rabbet. Typically, doors are 1-3/4″ thick. The rabbet for these doors will be 1-15/16″. The extra 3/16″ allows for silencers or adhesive gasketing to be installed and still allow the door to be closed flush with the face of the frame.

On an equal rabbet profile the rabbet dimensions will be the same (or “equal”). On an unequal rabbet profile the rabbets are different dimensions: one rabbet is usually going to be 1-15/16″ to receive a door that is 1-3/4″ thick while the other rabbet will be 1-9/16″ to receive a door that is 1-3/8″ thick if needed. Different manufacturers may stock equal rabbet or unequal rabbet frames.

Only one door is usually installed in a double rabbet frame. However, in situations like communicating doors between hotel rooms, an equal rabbet frame can be used where a door is installed in both rabbets.

3. Double Egress Profile

 

Double egress hollow metal frame profiles are used in openings that are often fire-rated pairs that separate corridors. They are often called cross-corridor openings. Each jamb’s profile is opposite of each other. This allows the doors to swing it opposite directions. They help control traffic flowing through the corridor. Traffic can push through the opening no matter which side they approach the opening.

The head of the frame is also unique in that the stop of the frame is opposite on each door side. See image below.

Also see the typical dimensions of the double egress profile below.

4. Cased Opening Profile

 

The cased opening frame profile is a profile that does not include a stop. This frame profile is most often used in openings where no door will be used. It provides a clean finished appearance for an opening in the wall where people will be passing through but no security is needed.

A cased opening profile is also used for double acting doors (doors that swing both in and out). Think of a restaurant kitchen door where staff is passing both in and out of the door constantly. Because there is no stop on the frame the door can swing either way, usually on spring hinges or pivots.

Conclusion

These 4 hollow metal frame profiles will generally meet the needs of the openings in a building. Custom options are available to meet unique circumstances or other types of openings, such as pocket door frames where the door slides into a cavity in the wall. Each frame profile will have certain dimensions and requirements to be aware of. If you have questions you can talk with a Beacon sales rep and find a solution that meets your needs.