/ Field knowledge · IMC 502.12
A high grille over a coating floor is not 502.12.
An enclosed Class I organic-coating process is not a paint closet with a bath fan. IMC 502.12: exhaust ≥ 1 cfm per square foot of solid floor, pick up at floor level, discharge outdoors, and sweep the floor with clean makeup air. A high grille at the opposite wall leaves the vapor on the slab. That is the miss 502.12 is written to catch.
Educational 2024 International Mechanical Code (IMC) 502.12 from Daily Code Talk (same post as 502.11–502.20). Confirm the adopted edition. Distinct from 502.8 maximum allowable quantity (MAQ) and 502.1.2 gasoline. This is not a coating-booth design.
- ≥ 1 cfm per square foot of solid floor. Floor area, not wall area.
- Pickup at floor level — solvent vapor is heavier than air.
- Discharge outdoors. Sweep the floor with clean makeup air. Do not take makeup from a hazardous room.
- Do not manifold this into environmental return. 509 hazardous exhaust is a different question if concentrations are high.
On the set: the exhaust schedule should show the floor area used for the 1 cfm/ft² basis, inlet height, outdoor discharge, and makeup-air source. If the room is called “paint” but the process is Class I organic coating, design to the process — not the room name.
A 400-square-foot coating room with a 150-cfm ceiling fan
1 cfm/ft² on 400 ft² is 400 cfm at the floor, plus makeup that actually sweeps. A high grille does not count as floor pickup.
Source: Daily Code Talk — IMC 502.11–502.20 · tool: 1 cfm/ft² screen · projector: 502.11 · spray: 502.7 · 509: hazardous exhaust.
What to send
Floor area of the enclosed coating room, a section showing inlet height, and whether discharge and makeup are dedicated.
If the coating room only has a high ceiling grille
Send the floor area and the section. Masterbuild will say whether 502.12 still has no floor pickup — or 502.12 still has less than 1 cfm per square foot.
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. 1 cfm per square foot of solid floor, floor-level pickup, outdoor discharge, and clean makeup sweep are 2024 IMC 502.12 education from Daily Code Talk — not a coating-booth design. This page is not legal advice.