Type I construction is the most fire-resistant classification in the International Building Code (IBC): structural elements, walls and floors are noncombustible, usually concrete or protected steel, with the highest required fire-resistance ratings.
There are two subtypes. Type IA generally requires a 3-hour rating for the primary structural frame and 2 hours for floors; Type IB generally requires 2 hours for the frame and floors. Type I buildings have the most generous height and area allowances and are used for high-rises, hospitals and large assembly buildings. See Type II construction.
In parking structures
- Podiums. In mixed-use buildings, a concrete parking podium is often built as Type IA, so lighter construction can be stacked above it under the IBC’s podium provisions, separated by a rated horizontal assembly.
- Below-grade and enclosed garages. Garages beneath other buildings frequently need Type I construction to match or support the building above.
- Concrete. Cast-in-place and precast concrete members can often achieve Type I ratings through their dimensions and cover, without spray fireproofing.
The Parkonomics view
In parking, Type I usually appears because of what sits above or beside the garage, not because of the cars. Decide early whether the garage is a standalone building or the base of another one; the answer changes construction type, separations and cost.
Related terms: Type II Construction, International Building Code, 1-Hour Fire Resistance, Fire Wall, Enclosed Parking Garage