AWC Design CLT 5-ply floor (2-hr calculated)

2-Hour Fire Rated Mass Timber — CALCULATED per the char method (mechanics-based design procedure in th

CALCULATED per the char method (mechanics-based design procedure in the US CLT Handbook, Chapter 8 — the same methodology adopted in NDS Chapter 16 / referenced by IBC 722.7). A 5-ply V2-grade (ANSI/PRG 320) CLT floor, 1-3/8 in laminations, 6-7/8 in total: the worked example shows 2.84 in of char after 90 minutes with the remaining section still carrying load, i.e. 90 minutes exposed; adding one directly applied layer of 5/8 in Type X gypsum board contributes 30 minutes (90 + 30 = 120 min), giving a 2-hour calculated rating. Not a fire test.