Hollow Metal Door Frames: Types, Profiles & Installation Overview

What Is a Hollow Metal Door Frame?

A hollow metal door frame (also called a steel door frame or buck) is the structural surround that supports and anchors a commercial door. Frames are manufactured from cold-rolled or galvanized steel and are designed to work with hollow metal doors in commercial, industrial, and institutional buildings.

Types of Hollow Metal Frames

Knocked-Down (KD) Frames

Shipped in three pieces (two jambs and a head) and assembled on-site. Best for new construction where the frame is set before the wall is built. Easier to ship and store.

Welded Frames

Factory-welded into a single unit. More rigid and square than KD frames. Preferred for masonry construction where the frame is set into a block or concrete wall.

Slip-On Drywall Frames

Designed to slip over an existing wood stud rough opening after drywall is installed. Ideal for interior partitions and renovation projects.

Frame Profiles & Throat Sizes

The throat size (also called the profile depth) must match your wall thickness:

• 4-9/16": Standard for 2×4 stud walls with drywall.
• 5-1/4": For 2×6 stud walls or thicker assemblies.
• 6": For masonry or CMU walls.
• Custom: Available for non-standard wall thicknesses.

Frame Anchors

Frames are secured to the wall using anchors appropriate for the wall type:

• Stud anchors: For wood or metal stud walls.
• Masonry T-anchors: For CMU or brick walls.
• Floor anchors: Secure the base of the jambs to the floor slab.

Ordering a Frame: What You Need to Know

1. Rough opening dimensions (width × height)
2. Wall thickness (for throat size)
3. Wall type (stud, masonry, existing opening)
4. Door hand (swing direction)
5. Hardware prep (hinge locations, strike location, closer reinforcement)
6. Fire rating requirement (if applicable)