Most framing members used in Type IV Construction (Heavy Timber) are not required to have a fire-resistance-rating and the connections of those framing members are not required to be protected. If Heavy Timber framing is required to have a fire-resistance-rating, then the connections are required to be protected for a 1-hour rating. The IBC states:
722.214.171.124 Fastener protection. Where minimum 1-hour fire-resistance-rating is required, connectors and fasteners shall be protected from fire exposure by 1-1/2 inches (38 mm) of wood, or other approved covering or coating for a 1-hour rating. Typical details for commonly used fasteners and connectors are shown in AITC Technical Note 7.