What Is Architectural Chases Concealment? (Framing Code)
Architectural chase concealment is the use of framed, finished enclosures to hide building services or other nonstructural elements while keeping them safe and serviceable. There is no single “concealment” code. The adopted building, fire, electrical, plumbing, and mechanical rules apply, along with structural limits, inspection requirements, and equipment instructions.
“Can we hide the pipe without making it impossible to reach later?” A homeowner asked me a version of this while planning a finished wall. That is the right question. A chase should conceal what needs covering, but it must not conceal a structural problem, block service access, or create an unsafe path for fire and smoke.
Plan the Chase Around Structure, Services, and Applicable Codes
An architectural chase is a framed enclosure that creates a route or space for services such as pipes, ducts, wiring, or vents. Chase concealment describes how that space is finished into the building. Its size and construction depend on what it contains, the surrounding structure, and the codes adopted by the local jurisdiction.
“Framing code” is not one rule that approves every hidden enclosure. The International Residential Code (IRC), International Building Code (IBC), and trade codes may apply, but local amendments and the authority having jurisdiction control. Confirm the applicable code editions before work starts.
Survey the route before setting dimensions
Start by identifying the chase’s purpose and everything it will contain. Look for framing members, wiring, plumbing, ducts, equipment, rated walls and floors, and places that need future access. Do not assume an existing wall is nonbearing or unrated based on its finish.
Then check permits and design needs. A new enclosure may change a room layout, affect a rated assembly, or involve structural work. Ask the building department or a qualified designer when the scope is unclear. Photograph existing conditions before covering anything.
Size the chase from the contents outward
Measure services and their required clearances first. Add space for supports, insulation where required, fittings, and access to components. A chase that fits a straight pipe may not fit a valve, duct elbow, electrical box, or cleanout.
Do not use a generic airflow figure to size a duct chase. Duct dimensions and airflow depend on the system design. Use the mechanical design and equipment instructions, and preserve required access and clearances.
| Chase contents | Check before framing | Common planning error |
|---|---|---|
| Electrical wiring or boxes | Box accessibility and wire protection | Closing a box behind fixed finish |
| Plumbing pipe | Cleanout and valve access; support needs | Leaving no room to remove or service a fitting |
| Duct or equipment | Designed duct size, service access, and required clearances | Squeezing or altering a duct to fit the chase |
| Mixed services | Required separation, supports, and access for each trade | Designing for one service and blocking another |
Next step: Make a dimensioned sketch showing the route, contents, access points, and nearby rated boundaries before buying framing materials.
Confirm Access, Clearances, and Fire-Rated Boundaries
A concealed service still needs to work as intended and remain reachable where codes require access. Clearances depend on the equipment and assembly, so check the adopted codes, product instructions, and approved plans. Also identify whether the chase passes through a rated wall, floor, or ceiling before deciding how to close it.
Keep required service points reachable
Under NEC §314.29, electrical boxes must remain accessible without removing building parts or damaging the building finish. A concealed box cannot simply be buried behind drywall or a fixed panel. An access opening may work if it leaves the box reachable and complies with the applicable requirements.
Plumbing cleanout access is governed by the locally adopted plumbing code. For example, IPC §708 addresses cleanouts, but the local code and installation conditions determine the details. Plan the opening so a person can reach and use the cleanout, not merely see where it is.
Check equipment instructions for service clearances and any required combustion-air or separation clearances. Do not cover a damper, valve, junction box, cleanout, or other service point with a permanent finish.
Protect fire and smoke boundaries
Fireblocking limits the movement of fire through concealed spaces. IRC §R302.11 requires fireblocking at specified locations, including certain floor and ceiling levels and around some penetrations. The exact locations and acceptable materials depend on the adopted code and the construction.
A chase can create a continuous hidden path for smoke and fire, especially when it crosses floors or connects concealed spaces. A neat finish does not solve that risk. Resolve where fireblocking is needed before closing the enclosure.
If a chase penetrates a fire-resistance-rated assembly, use the applicable tested or listed system. IBC §714 addresses penetrations through rated construction. An ordinary access panel or bead of sealant does not preserve a fire rating by itself. The protection must suit the assembly, penetrating item, and required rating.
Next step: Mark every access opening and rated boundary on the plan. Confirm the proposed fireblocking and penetration details before installing finish material.
Frame and Conceal Without Weakening the Assembly
A chase must not gain space by weakening structural members without approval. The 2021 IRC provides limits for notches and holes in conventional studs, but those limits are not permission to cut every wall. First identify the wall type and framing; engineered members require their own design or an approved repair.
Apply stud notch and hole limits carefully
Under 2021 IRC §R602.6, notches in exterior or load-bearing studs are generally limited to 25% of stud depth. Notches in nonbearing interior studs are generally limited to 40%. Stud holes are generally limited to 40% of stud depth, with limited provisions allowing up to 60% in specified doubled-stud conditions. Keep a hole’s edge at least 5/8 inch from the stud edge.
These are model-code examples. Check the full adopted provision and its conditions, including any limits on which studs may be bored. For a standard nominal 2-by-4 stud, the actual depth is typically 3.5 inches: 25% is 7/8 inch, 40% is 1.4 inches, and 60% is 2.1 inches. Verify actual member dimensions and do not apply these calculations to engineered lumber.
| Example member depth | 25% notch limit | 40% limit | 60% limit, only where allowed |
|---|---|---|---|
| 3.5 in. | 0.875 in. | 1.4 in. | 2.1 in. |
| 5.5 in. | 1.375 in. | 2.2 in. | 3.3 in. |
Do not cut, notch, or bore a structural member beyond the adopted limits. Do not cut engineered joists, trusses, or other engineered members unless the manufacturer or an approved design permits it. If a planned route does not fit, revise the chase, reroute the service, or obtain a designed repair.
Build the enclosure as a separate frame where practical
A separate framed enclosure can provide room for services without cutting existing studs. It still needs sound attachment and must not block required access, ventilation, or fire protection. Coordinate framing with the trades so supports and penetrations are in place before the chase is closed.
Use fireblocking where required, and protect penetrations through rated assemblies with the correct listed system. Keep the enclosure’s access panel usable after paint, trim, or other finishes are installed.
Next step: Have framing and utility work inspected at the required stages. Do not cover work that an inspector or designer still needs to see.
Representative Installation Cases and Planning Checks
These examples show common code questions rather than documented projects. They are useful for planning, but they do not replace a site inspection or approval. The right detail depends on the building, the service, the rated assembly, and the locally adopted rules.
Plumbing stack in a finished room
A vertical pipe may fit in a narrow enclosure, but a cleanout or valve can change the required dimensions. In planning, locate the access point first, then size the opening so it can be used and left accessible after trim is installed. Check whether the chase crosses floor or ceiling spaces that need fireblocking.
A common failure is to frame a tight box around the pipe and discover that the cleanout cap cannot be removed. The remedy is to revise the opening or chase before finish work, not to rely on cutting the wall later.
Duct crossing a wall or floor
A duct route needs the designed duct dimensions, fittings, supports, and any required service clearances. If it passes through rated construction, identify the applicable penetration protection before framing the opening. A decorative cover cannot substitute for a tested or listed firestop system where one is required.
The practical check is to compare the duct plan with the framing plan and rated-assembly details. If the route does not fit without changing the duct or cutting structural framing, stop and coordinate a revised design.
Wiring concealed behind a new enclosure
A framed cover can hide wiring, but it cannot make a junction box inaccessible. Locate boxes on the plan and preserve access through an appropriate opening. Check that the proposed framing does not damage cables or prevent required protection and support.
Next step: Treat each service as its own design check, then review the combined chase for conflicts before closing it.
Verify Inspection, Serviceability, and Concealed-Work Records
Final verification checks that the chase meets the approved plan, keeps services usable, and includes required fire and structural protections. Inspection timing varies by jurisdiction and project. Keep documentation of concealed work so future repair does not depend on guesswork.
Before closing the chase, confirm:
- Framing matches the plan, with no unapproved cuts to structural members.
- Electrical boxes, plumbing cleanouts, dampers, and service points remain accessible.
- Required fireblocking is installed at the specified locations.
- Penetrations through rated assemblies use the appropriate listed systems.
- Duct and equipment clearances match the design and manufacturer instructions.
- Required inspections are complete.
Take clear photographs before finish materials cover the work. Include wide views that show where the chase sits and close-ups of fireblocking, penetrations, and access points. Keep the photos with plans, inspection records, and product details.
The final check is simple: Can the services be inspected and maintained, and does the finished chase preserve the required structural and fire protections? If not, it is not ready to close.
Frequently Asked Questions
These short answers summarize the main code and installation points. Exact requirements depend on the adopted code edition, local amendments, building type, and approved project details. When an answer depends on those conditions, confirm it with the authority having jurisdiction or a qualified design professional.
Is architectural chase concealment covered by one framing code?
No. Building, fire, electrical, plumbing, and mechanical rules may all apply. The locally adopted codes and amendments control.
What is a chase in building construction?
A chase is a framed or built enclosure that routes or covers services such as pipes, ducts, or wiring while providing required space and access.
How deep can I notch a load-bearing stud?
Under the 2021 IRC model-code example, a notch in an exterior or load-bearing stud is generally limited to 25% of the stud depth. Confirm the adopted code and conditions.
How large can a hole be in a stud?
The 2021 IRC generally limits a stud hole to 40% of stud depth. Limited provisions allow up to 60% in specified doubled-stud conditions. Keep the hole edge at least 5/8 inch from the stud edge.
Can I cut an engineered joist or truss for a chase?
Not unless the manufacturer or an approved design permits the cut or specifies a repair. Do not apply ordinary stud limits to engineered members.
Can a junction box be hidden behind a fixed panel?
No. NEC §314.29 requires electrical boxes to remain accessible. A suitable access opening may be used if it preserves access and complies with applicable rules.
Does a chase need fireblocking?
It may. IRC §R302.11 requires fireblocking at specified concealed-space locations. Check the adopted code and the chase layout before closing it.
Can ordinary sealant protect a penetration in a rated wall?
Not by itself. Use a tested or listed system that is appropriate for the rated assembly and the item passing through it.
How do I size a duct chase?
Use the designed duct dimensions, fittings, supports, and required clearances. There is no single chase size or generic airflow value that suits every system.
When should I photograph the chase?
Before closing it. Record framing, fireblocking, penetrations, service routes, and access points, and keep the images with project documents and inspection records.
(This article was written by one of our staff writers, Garrett Vance. Visit our Meet the Team page.)
