/ Field knowledge · IMC 304
The listing has to survive the garage floor.
IMC 304: install per approval, listing, manufacturer’s instructions, and the IMC — and keep the MI on site. A schedule without an installation detail is the comment.
Educational 2024 IMC 304.1–304.4. Confirm the adopted FBC Mechanical edition and the listing. This is not an installation approval. Packet: 304.1 PDF · ES.
- 304.1. Install per approval + listing + MI + IMC. Keep MI on site for inspection.
- 304.2 conflicts. If code vs listing/MI conflict, IMC governs — except when IMC is less restrictive; then follow listing/MI. Note the MI page on the schedule.
- 304.3 ignition elevation. In garages, fuel-dispensing, and hazardous locations: ignition source ≥ 18 in above the floor. Rooms that open directly to a private garage are part of the garage. FVIR-listed appliances need no elevation.
- 304.3.1 parking garages. Rooms with fuel-fired appliances connecting to a parking garage need a two-door vestibule; one door allowed if ignition source is elevated per 304.3 (exception: 304.6).
- 304.4. No ignition-source equipment in Group H or control areas with open use/handling/dispensing of flammables/explosives.
WH / furnace next to a garage
Treat the communicating room as garage for 304.3. Choose FVIR or provide 18-in elevation; add vestibule where 304.3.1 triggers. Draw it.
Source: DCT 304 Part 1 · location: 303 · access: 306 · garage mount: 304.6–304.7 · roof guards: 304.11.
What to send
The room (garage-adjacent or not), the appliance listing (FVIR or not), and photos of the existing install on a replacement.
If the water heater is in or next to a garage
Send the room relationship and the listing. MasterBuild will say whether 18 in, FVIR, or a vestibule is even on the path.
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.