What This Article Covers and Who It Helps
If you are ordering or specifying hollow metal frames and the submittal asks for a rabbet profile, the choice between single rabbet and double rabbet is not cosmetic. It affects wall thickness fit, hardware coordination, fire-rating eligibility, and what the door actually closes against. This guide breaks down both profiles in plain language for contractors pulling a job, facility managers reviewing submittals, and architects writing a frame schedule for the first time.
What Is a Rabbet on a Hollow Metal Frame?
A rabbet is the recessed ledge inside the frame profile that the door closes into. It creates the stop surface the door face contacts when shut. The rabbet also defines the soffit area between the two rabbets (on a double-rabbet frame) and determines how much of the frame face is visible on each side of the wall.
The standard rabbet is sized approximately 3/16 inch wider than the door thickness, which is why a 1-3/4 inch door uses a rabbet roughly 1-15/16 inches wide. That extra clearance is where silencers (rubber grommets) live, maintaining the required 1/16-inch air space between the door face and the frame stop.
Single Rabbet: What It Is and When to Use It
A single-rabbet frame is rabbeted on one side only. The door installs in that one rabbet, and on the opposite face of the wall the frame presents a flat or cased appearance with no stop. The soffit runs from the stop to the face on the non-rabbeted side.
Typical Applications
- Thin partitions 3-1/2 inches or less in depth, where a double rabbet would leave almost no soffit between the two stops
- Openings where aesthetics require a clean flat look on the push side, such as retail interiors or office fronts
- Situations where hardware on the soffit (surface coordinators, parallel-arm closer brackets) would be too cramped in a standard double-rabbet profile
- Single-rabbet frames can be used in any wall depth when the architect specifies them for visual reasons
Hardware Coordination Notes
- The soffit on a single-rabbet frame is wider on the non-rabbeted side, which can actually give more room for surface-mounted hardware
- Latch bolt clearance to the jamb face must be checked: on a narrow face dimension, the latch may contact the frame before full throw, requiring an extended-lip strike
- Frame stop height is still the standard 5/8 inch, so vertical rod exit devices, rim exit devices, and coordinators behave the same as on a double-rabbet frame
Double Rabbet: The Most Common Commercial Frame Profile
A double-rabbet frame is rabbeted on both sides, with a stop centered in the soffit. The door closes against the stop, and each wall face sees an equal (or unequal) rabbet shoulder. This is the standard profile for the vast majority of commercial openings.
Equal vs. Unequal Double Rabbet
- Equal rabbet: Both rabbets are the same width, typically 1-15/16 inches each for a 1-3/4-inch door. This is the default and covers most standard openings in schools, healthcare facilities, office buildings, and industrial plants.
- Unequal rabbet: One rabbet is wider than the other. Used when two doors of different thicknesses share the same frame, or when a specific hardware condition demands more clearance on one side. Less common and requires explicit ordering.
Typical Applications
- Standard single-door openings in corridor walls, stairwells, and tenant suites across virtually every building type
- Fire-rated openings: double-rabbet frames are the most widely tested and listed configuration for fire door assemblies
- Healthcare: patient room doors, clean corridor doors, and behavioral health openings where the full stop is needed for latching hardware and positive closure
- Industrial and warehouse applications where door abuse is expected and a full stop provides a solid closing surface
- Schools: classroom doors, gym entries, and cafeteria service doors where hardware schedules are dense and predictable frame geometry simplifies install
Hardware Coordination Notes
- Soffit width on a double-rabbet frame varies with jamb depth. Soffits narrower than 2 inches may require auxiliary mounting hardware for parallel-arm closer brackets and surface-mounted coordinators
- Frame stop height of 5/8 inch is standard. If the opening uses a soffit-mounted coordinator or a surface vertical rod exit device, the stop height interacts directly with those products and may need adjustment
- Frame stop weatherstripping mounted on a 1/2- to 3/4-inch stop can create a knuckle-busting condition on the push side when paired with a 2-3/4-inch backset lockset. The fix is a longer backset or a cased opening frame with an applied stop
- Double-rabbet frames accept the widest range of exit devices from lines like Sargent, Corbin Russwin, and Hager without special prep modifications
Side-by-Side Comparison
- Wall depth suitability: Single rabbet works in thin walls (3-1/2 inches or less) or by aesthetic choice; double rabbet fits any standard wall and is the default for most partition types
- Fire-rating availability: Both profiles can be fire rated; double rabbet has broader tested and listed configurations across frame manufacturers
- Soffit space for hardware: Single rabbet offers more soffit clearance on the non-rabbeted side; double rabbet provides a predictable centered stop for hardware referencing
- Hardware schedule complexity: Double rabbet is the assumed baseline in most hardware schedules; deviating to single rabbet should be called out explicitly so the hardware supplier can verify strike projections and closer arm geometry
- Communicating frames and paired openings: Double-rabbet frames are standard for pairs; single-rabbet pairs exist but are less common and require close coordination on astragal and exit device selection
What Changes at the Hardware Level When the Profile Changes
The frame profile is not just a structural choice. It directly shapes what goes on the door and frame:
- Strikes: Extended-lip strikes may be needed on single-rabbet frames with narrow face dimensions to prevent the latch from contacting the jamb prematurely. Hager and Rockwood both offer extended-lip options in standard commercial strikes.
- Closers: Top-jamb closer mounting requires a minimum frame face of 3-7/8 inches regardless of rabbet type. Parallel-arm mounting references soffit width. If the soffit is tight, a mounting plate accessory may be required. Hager, PDQ, and Norton closers all offer auxiliary mounting plates for these conditions.
- Exit devices: Rim exit devices reference the frame stop for their strike. Surface vertical rod exit devices reference both the stop and the soffit. Confirm soffit depth before specifying. Sargent and Corbin Russwin exit device lines include strike options for both standard and narrow soffits.
- Hinges: Profile does not affect hinge selection directly, but it affects where the hinge cutout is located in the frame. Confirm hinge prep matches the door thickness and rabbet depth called out on the frame order.
Ordering the Right Profile: What to Confirm Before the Frame Ships
Frame profile decisions are made at the factory. Once a hollow metal frame ships, the rabbet profile cannot be changed in the field. Before releasing an order, confirm:
- Actual wall thickness (throat size = overall jamb depth minus 1 inch)
- Door thickness (determines rabbet width)
- Whether the opening is fire rated (affects profile options and listing requirements)
- Hardware items that reference the soffit or stop (coordinators, closers, exit device strikes)
- Whether weatherstripping will be applied to the stop (affects backset selection for locksets)
- Equal or unequal rabbet requirement if two door thicknesses are involved
Get the Right Frame Profile the First Time
DoorwaysPlus.com carries hollow metal frames in single-rabbet, double-rabbet, and specialty profiles, along with the compatible closers, exit devices, strikes, and hinges from preferred lines including Hager, Sargent, Corbin Russwin, Rockwood, PDQ, and Norton. If your project has an unusual wall condition, a fire-rated requirement, or a hardware schedule that needs to coordinate with the frame profile, our team can help you work through it before the order goes to the factory.