Chapter 3 contains general regulations that support many mechanical scopes. Apply them with the project-specific chapter, adopted code, exceptions, listing conditions, manufacturer instructions, referenced codes, and AHJ procedures; a more specific requirement can change the path.
What this chapter covered
301 - General scope, energy, identification, listing, labeling, fuel type, repair, wind, flood, seismic, and rodentproofing requirements. 302 - Protection of structure: openings, framing alterations, trusses, rated assemblies, and firestopping coordination. 303 - Equipment location: prohibited locations, damage protection, indoor/outdoor/pit locations, elevator shafts, and special occupancy limits. 304 - Installation: approval, listing, manufacturer instructions, ignition-source elevation, garage rules, clearances, guards, construction protection, and area served.
305 - Pipe support: material compatibility, structural attachment, support spacing, physical-damage protection, and shield plates. 306 - Access and service space: rooms, attics, underfloor spaces, roofs, elevated structures, sloped roofs, receptacles, ladders, and service platforms. 307 - Condensate disposal: approved receptor, pipe size/material, slope, auxiliary drain protection, water-level detection, traps, maintenance access, and pump shutdown. 308 - Clearance reduction: listed appliance limits, approved noncombustible protective assemblies, UL/table basis, airspace, and limitations.
309 - Temperature control: occupiable interior spaces need a compliant heating path unless an exception applies. 310 - Explosion control: fire-code trigger and IFC 911 design basis must be coordinated where explosion hazards exist. 311 - Smoke and heat vents: roof vent requirements come from the IFC and must not conflict with mechanical roof layouts. 312 - Heating and cooling load calculations: equipment sizing must trace to ASHRAE/ACCA 183 or an approved equivalent method using IECC design parameters.
Seven recurring review patterns
1. Equipment location or environmental exposure is unresolved. 2. Access and service paths are not dimensioned. 3. Pipe-support criteria are not tied to material, size, orientation, and applicable source. 4. Structural or rated-assembly coordination is incomplete. 5. Condensate routing and overflow response are not shown. 6. Clearance reduction is only a note, not a documented assembly. 7. Equipment capacity does not trace to the approved load method and inputs.
Use a cover-sheet control set, not a placeholder note
State the adopted-code basis and require listed/manufacturer clearances, but place actual dimensions and access/removal paths on plans or details. Provide a piping-support schedule tied to material and size, identify condensate disposal and overflow controls, and route structural, fire, energy, fuel-gas, electrical, plumbing, flood, wind, and seismic decisions to the responsible documents.
Code Path: 301 general requirements -> 302 structure -> 303 location -> 304 installation -> 305 pipe support -> 306 access -> 307 condensate -> 308 clearance reduction -> 309 heating requirement -> 310 explosion control -> 311 smoke/heat vents -> 312 load calculations.
Section 301.7: Verify that listed and labeled equipment remains within its application and conditions of use, or document the valid approved alternative path.
Section 305: Pipe support spacing is a function of pipe material, size, and run orientation - not contractor preference.
Section 306.2: The service space must be large enough to service the equipment without removing other building components.
Check: Before You Submit
Confirm the permit set notes: 'All equipment installed per manufacturer's instructions and applicable listing requirements.'
Verify pipe support schedules show material, size, and maximum spacing per Section 305 tables.
Confirm all equipment access paths in attics, crawl spaces, and closets are dimensioned and comply with Section 306.
Review Risk:
Missing or obstructed access to equipment in confined locations.
Equipment relocation from an approved location to a prohibited location during construction without a revised permit.
Pipe support intervals not shown on the plan - contractor uses field judgment instead of code-required spacing.
Masterbuild QA Lens
Run a Chapter 3 sweep before issue and again before concealment: approval evidence, location, structural/rated-assembly coordination, installation conditions, support, service/removal access, condensate, clearances, heating basis, fire-code routes, and load calculations. Assign each unresolved item an owner and stop condition.
Drawing / Submittal Check
Verify exact equipment/model evidence; listed and manufacturer installation conditions; access and removal dimensions; garage or hazardous-location conditions where applicable; support schedule; condensate route and overflow response; clearance-reduction detail; heating exception basis; fire-code coordination; and load-to-equipment traceability.
Common Review Risk
The drawings show a compliant concept but not enough project-specific proof for procurement, installation, inspection, or maintenance. Generic notes do not replace dimensions, selected products, calculation inputs, coordinated details, or approved submittals.
When To Escalate
Escalate equipment relocation, structural changes, rated-assembly substitutions, clearance conflicts, hazardous/process conditions, flood/wind/seismic exposure, disputed listing conditions, uncertain exceptions, or any field change that affects design, fee, schedule, permit documents, testing, or professional responsibility.
Educational Disclaimer
This article is educational content summarizing IMC Chapter 3 concepts. It is not project-specific engineering advice. Consult the adopted code edition in your jurisdiction.