The locally adopted building code establishes fire resistance ratings for various building elements based on the size, height, and intended use of a building. The requirements for fire resistance come from a table similar to the one below.
A building must meet all of the criteria described in the table to achieve one of the five types of construction. (Note that four of the types have “A” or “B” subgroups.)
For example, to meet the requirements of Type IB construction, a building’s structural frame, bearing walls, and floor assemblies must be a minimum 2 hour rating, and the roof construction must be 1 hour.
If such a building were to have 2 hour rated structural frame, bearing walls, and floor assemblies but non-rated roof construction, it would have to be classified no better than Type IIB. This “lower” rating would limit its size, height and intended use.
Knowledge Check: Can you identify the building code relationship between construction types and required fire resistance rating?