/ Field knowledge · IMC 502.6
A ceiling fan over a Type II plant is not 502.6.
A dry-cleaning room is not a storage closet with a bath fan. IMC 502.6: vent to control solvent vapors. Type II: ≥ 1 cubic foot per minute per square foot (cfm/ft²) in the dry-clean and drying rooms. Type IV / V: exhaust based on the loading-door area, or an exhaust hood sized to that opening. A high grille over a closed machine does not sweep the door. That is the miss 502.6 is written to catch.
Educational 2024 International Mechanical Code (IMC) 502.6 from Daily Code Talk (same post as 502.2–502.7). Confirm the adopted edition. Distinct from 502.12 enclosed coating (also 1 cfm/ft², but floor pickup for Class I coating) and 502.7 spray. This is not a dry-clean plant design. The code does not put a single feet-per-minute number on the Type IV/V door on this page — put the basis (door area or hood at the opening) on the exhaust schedule. Packet: 502.6 PDF · ES.
- Type II: 1 cfm/ft² in the dry-clean room and the drying room — floor area, not wall area.
- Type IV / V: exhaust tied to the loading-door area, or a hood over that opening. Design to the door, not the room name.
- Discharge outdoors. Do not recirculate solvent vapor into the shop. Do not take makeup from a hazardous room.
- Related 502.2: aircraft fueling/defueling vents at floor level or in the slab so heavy fuel vapor cannot pool — a different process, same idea: pick up where the vapor sits.
On the set: the exhaust schedule should show Type II vs IV/V, the floor area used for 1 cfm/ft² (Type II), or the door/hood basis (Type IV/V), and outdoor discharge. If the room is tagged “laundry,” ask what solvent and which type — the name on the door is not the code path.
A Type II plant with a 150-cfm ceiling fan over 400 square feet
1 cfm/ft² on 400 ft² is 400 cfm in the dry-clean and drying rooms. A Type IV/V machine with no hood at the loading door leaves the operator in the vapor when the door opens.
Source: Daily Code Talk — IMC 502.2–502.7 · tool: Type II / door screen · coating: 502.12 · spray: 502.7.
What to send
Machine type (II / IV / V if you know it), floor area of the dry-clean and drying rooms, and whether there is a hood at the loading door.
If the dry-clean room only has a ceiling fan
Send the machine cut sheet and the floor area. Masterbuild will say whether 502.6 still has no 1 cfm/ft² in the Type II rooms — or 502.6 still has no exhaust at the Type IV/V loading door.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
Masterbuild provides engineering services under a written scope. Nothing on this page is project-specific engineering advice, a code interpretation for your project, or a representation about permit approval. Confirm the adopted edition. Type II 1 cfm/ft² in dry-clean and drying rooms, and Type IV/V exhaust based on loading-door area or a hood at that opening, are 2024 IMC 502.6 education from Daily Code Talk — not a plant design and not a door velocity. This page is not legal advice.