In Type IV construction, loadbearing exterior and interior walls shall have a fire resistance rating of not less than how many hours?

In Type IV construction, loadbearing exterior and interior walls shall have a fire resistance rating of not less than how many hours?

• A. One hour
• B. Three hours
• C. Four hours
• D. Two hours

Answer: (D)

In Type IV construction, heavy timber elements give the structure substantial mass that helps resist fire, but the loadbearing walls still must retain their integrity long enough for occupants to escape and for firefighters to respond. The minimum fire-resistance rating specified for these walls is two hours. That rating provides a practical balance: it’s long enough to protect structural stability during a typical fire event, yet not so high as to over-restrict construction. A one-hour rating would be insufficient for the loadbearing walls in this type of construction, while ratings of three or four hours would be more restrictive than the standard for Type IV.

In Type IV construction, heavy timber elements give the structure substantial mass that helps resist fire, but the loadbearing walls still must retain their integrity long enough for occupants to escape and for firefighters to respond. The minimum fire-resistance rating specified for these walls is two hours. That rating provides a practical balance: it’s long enough to protect structural stability during a typical fire event, yet not so high as to over-restrict construction. A one-hour rating would be insufficient for the loadbearing walls in this type of construction, while ratings of three or four hours would be more restrictive than the standard for Type IV.