/ Field knowledge · IMC 302
Do not cut the truss. Do not guess the firestop.
IMC 302: openings, hangers, curbs, and sleeves cannot weaken the building. “Fire caulk” is not a tested system. Cutting a truss in the field without a PE letter is the stop-work.
Educational 2024 IMC 302. Confirm adopted IBC/AISI editions. This is not a structural design or a firestop listing.
- 302.1: leave the structure safe per IBC.
- 302.2 rated/floor-ceiling penetrations: protect per IBC Chapter 7 using a tested firestop that matches the assembly, rating, and penetrant. IMC 302.2 does not contain a Table 302.2.
- Wood framing: cutting/notching/boring per IBC 2308.6. Engineered wood (trusses, SCL, GLB, I-joists): no field holes/notches unless the manufacturer or a PE approves.
- Trusses: no alterations or added loads (RTUs, water heaters, platforms) without written PE concurrence.
- Cold-formed steel: AISI S240 (structural) / S220 (nonstructural). Structural steel: holes/notches only as prescribed by the registered design professional.
Generic fire caulk
Each rated penetration needs a UL/Intertek design number and the products from that system. New truss loads need a manufacturer bulletin or PE letter on the S-sheets — not “drill as needed.”
Source: DCT 302 · dampers: 607 · location: 303.
What to send
Whether trusses are involved, the rated-wall plan, and the equipment operating weight if an RTU or tank is being added.
If the RTU lands on an existing truss
Send the roof framing photo and the unit weight. Masterbuild will say whether 302 is even on the path — or the firestop is a generic note.
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.