What Is Swing-Arc Concealment Design? (CAD Specs)
Swing-arc concealment design is the planning of a flush or disguised door so its full travel clears nearby objects while preserving required access and egress. It is a design method, not a separate building-code category. CAD drawings should show the hinge axis, door envelope, obstructions, clear opening, hardware, and applicable code checks.
A concealed door can look like part of a wall, yet still take up the same space as an ordinary door when it opens. That is the key paradox: visual simplicity does not reduce the physical swing. I treat the door as a moving part first and a finish detail second.
No single code sets a universal standard called “swing-arc concealment.” The adopted local building and fire codes control. Where applicable, the 2010 ADA Standards add requirements for accessible doors. Check with the local building department or authority having jurisdiction (AHJ) before construction, especially if the door serves an exit or is part of a fire-rated assembly.
Planning the Concealed Swing Arc
A swing arc is the area swept by a door as it rotates around its hinge or pivot axis. In CAD, show the door in plan at closed, intermediate, and open positions, then compare its full footprint with walls, fixtures, and circulation space. The drawing should use finished dimensions, not nominal door sizes.
Define the geometry in CAD
Set the hinge axis as the origin of a plan drawing. For a typical side-hinged door, let W be the distance from the hinge axis to the far edge of the panel, and let θ be its opening angle. The far edge follows a circular path with radius W. At any angle, its plan coordinates are x = W cos θ and y = W sin θ.
For example, a panel that is 30 inches wide has a 30-inch radius to its far edge. That does not mean a 30-inch circle fully describes the door: include panel thickness, handles, pulls, trim, and any hardware that protrudes. Model those parts or draw their maximum envelope separately. Keep any added clearance allowance as a project decision, not a claimed code value.
Record the real conditions
Before drawing the door, measure the finished opening and nearby space. Note floor and wall conditions, baseboards, casing, switches, furniture, and fixtures. Check how far the door projects at each angle, and whether an open panel will narrow a route or block access to another door.
Use a site sketch to record:
- Finished opening width and height
- Hinge or pivot location and intended swing direction
- Panel thickness, cladding, pull, and other projections
- Nearby obstructions and the dimensions of the route around them
- Floor level, threshold, and any change in level
Next step: Build the CAD plan from these field measurements, then test both the full swept path and the door’s final open position.
Access, Egress, and Clearance Checks
A clear swing path is not the same as a compliant doorway. The design must also preserve any required clear opening, accessible maneuvering space, and egress route. Which rules apply depends on the building, the door’s function, the adopted code, and local amendments.
Check accessible-door requirements
Where the 2010 ADA Standards apply, §404.2.3 requires at least 32 inches (815 mm) of clear opening, measured between the face of the door and the stop with the door open 90 degrees. A nominal door width does not prove that the opening meets this measure. Model the actual panel position and any hardware that affects the opening.
Under §404.2.5, an accessible threshold may be no more than ½ inch (13 mm) high. Changes in level over ¼ inch (6.4 mm) must be beveled as specified in that section. Other door requirements may apply too, including maneuvering clearances. Those clearances vary with approach direction and door conditions, so check the full standard rather than treating the 32-inch opening as the only test.
For non-fire-rated interior hinged doors where the ADA operating-force provision applies, §404.2.9 sets a maximum force of 5 lbf (22.2 N). Fire-door opening force is governed separately. Under §404.2.8, an accessible door closer, if used, must take at least 5 seconds to move from 90 degrees open to 12 degrees from the latch. Confirm which provisions apply to the project.
Protect egress and rated assemblies
A concealed panel may still be a required egress door or part of a rated wall or opening. Its appearance does not change its role. Concealment hardware, latches, locks, or finishes must not block required egress or defeat required self-closing and latching.
Do not field-alter a listed fire door or frame unless the alteration is supported by approved documentation. Concealed hinges or an unusual latch do not automatically preserve a fire rating. Confirm the assembly, hardware, and proposed changes with the AHJ and the listing information for the specific products.
Next step: Mark each applicable code check on the drawing and resolve conflicts before ordering hardware or cutting framing.
Framing, Hardware, and Finish Execution
The frame and hardware carry the door’s full installed weight and guide its movement. Choose them for the complete assembly, not for a bare slab. Reinforce the attachment points as required by the hardware maker and the framing conditions, while keeping any rated assembly intact.
Select hardware for the actual load
There is no universal code load rating for concealed swing hardware. Compare the manufacturer’s limits for door mass, width, thickness, and geometry with the finished door. Include cladding, attached storage, pulls, and any other load carried by the panel. Do not assume two hinge products with the same appearance have the same capacity.
Fasteners must suit the substrate and the hardware. A hinge attached to trim or unsupported drywall is not a sound substitute for a designed connection to framing. Follow the hardware maker’s installation instructions, including required fastener type, location, and edge distances. If the panel is unusually heavy or wide, ask the manufacturer or a qualified designer to confirm the configuration.
Coordinate the finish with the movement
A flush finish can hide gaps, but it cannot remove the need for working clearances. Check how the panel edge, wall finish, and pull pass each other through the full swing. Confirm that paint, veneer, or trim will not bind as the door moves. A mock-up can reveal finish conflicts, but it does not replace measured clear-opening and code checks.
| CAD or field item | What to specify | Why it matters |
|---|---|---|
| Hinge axis | Exact centerline and swing direction | Sets the door’s rotation path |
| Panel envelope | Width, thickness, cladding, pull, projections | Captures the full moving footprint |
| Hardware | Model and rated door mass, width, and geometry | Confirms suitability for the finished assembly |
| Clear opening | Measured with door at 90 degrees where required | Verifies accessible opening, not nominal size |
| Threshold | Finished height and bevel where applicable | Checks the accessible transition |
| Rated assembly | Listing and approved hardware details | Helps preserve required fire performance |
Next step: Confirm hardware and framing details before finishing the wall or panel; later changes can affect alignment and listed construction.
Operational and Code Verification
A door that looks aligned while closed can still bind, fail to latch, or reduce usable clearance when open. Test the finished installation through its full travel. Record the checks that apply to the project so the final appearance does not conceal an unresolved safety issue.
Use this sequence:
- Survey: Record the finished opening, wall and floor conditions, nearby obstructions, panel dimensions, and estimated finished mass. Identify egress, accessibility, fire-rating, and permit requirements.
- Resolve the swing: Draw the full swept envelope in plan and elevation. Check closed, intermediate, and open positions against routes, furniture, trim, switches, and required clear opening.
- Engineer and frame: Select manufacturer-approved hardware for the finished panel and substrate. Reinforce attachment points as required, and preserve rated construction.
- Install and adjust: Hang the door, align it, and set the latch and any closer according to the product instructions.
- Verify and document: Test full travel, clear opening, latching, operating force, and closer timing where applicable. Keep hardware details and code checks with the project records.
Illustrative design checks
These examples show how to use the method; they are not field reports or code approvals.
- A 30-inch-wide flush panel beside a wall return: The far edge sweeps on a 30-inch radius from the hinge axis. Draw the panel thickness and pull, then check whether the return intersects the panel at any angle. A clear-looking closed position does not answer that question.
- A concealed door on an accessible route: Open the door to 90 degrees in the drawing and measure from the door face to the stop. If the opening is below 32 inches, the nominal slab width does not cure the shortfall. Check other applicable maneuvering and threshold provisions as well.
- A concealed door in a rated assembly: First identify the required listing and approved door, frame, closer, and latch details. If proposed concealment changes are not covered by approved documentation, stop and seek an acceptable design rather than treating the finish as a cosmetic change.
Key check: The design is ready for finishing only when movement, clear opening, latching, and applicable code requirements have been verified.
FAQ: Swing-Arc Concealment CAD Specs
These answers define the core terms and checks used in a concealed-door CAD plan. Local code and project conditions still control. Treat the drawing as a coordination tool, not as proof of approval or a replacement for manufacturer instructions.
Is “swing-arc concealment” a building-code term?
No. It describes planning a concealed or flush door’s movement and clearances. The adopted codes govern the door’s safety and performance.
What should a swing-arc CAD drawing show?
Show the hinge axis, panel dimensions, full swept envelope, obstructions, door positions, clear opening, hardware, and applicable code checks.
How do I calculate the door’s swing radius?
For a conventional side-hinged panel, measure from the hinge axis to the far edge. That distance is the radius for the far edge’s path.
Can I use the nominal door width for the accessible opening?
No. Where the 2010 ADA Standards apply, measure the clear opening with the door open 90 degrees, between the door face and stop.
Does a concealed door need special hinges?
Not by code name alone. Select hinges or pivots rated by their manufacturer for the finished door’s mass, width, and geometry.
What if the door is part of a fire-rated wall?
Keep the required listed assembly intact. Confirm hardware and alterations with the listing documentation and AHJ.
Does a door that swings clear automatically meet egress rules?
No. Swing-path clearance is only one check. Egress requirements depend on the door’s function and adopted local code.
When should I verify closer timing and operating force?
When the relevant accessibility provisions apply. The 2010 ADA Standards specify a five-second minimum closer movement from 90 to 12 degrees and a 5 lbf maximum force for covered non-fire-rated interior hinged doors.
(This article was written by one of our staff writers, Garrett Vance. Visit our Meet the Team page.)
