The buildings are classified by type of construction, that is, literally, how the building are constructed as dictated by the International Building Code. The ranking takes into account a very important aspect: how well the building resists fire. As expected, thanks to the variety of materials from which the buildings are made there is a wide range of classes within this classification.
Type I-A and B
The type I-A buildings produce a building with exterior walls and a structural framework that is able to withstand fire for up to three hours. Both the floor and the sky ceiling need to resist fire for two hours, while the roof must withstand fire for an hour and a half. Buildings within such structures are usually at high altitude. The main difference between I-A and B type is the type I-B building has exterior walls and a structural frame that only has a fire resistance of two hours instead of three hours as type I-A.
Type II-A and B
The type II-A building is considered a building that is protected and is fireproof, and often includes new schools. These buildings have exterior walls, structural frames and ceiling, roof and floor that should last up to an hour. The main difference between the building type II-A and II-B type is that while the building type II-B is made of fireproof material has no fire resistance. Most commercial buildings fall into this type of construction.
Type III-A and B
Building construction type III-A includes buildings with walls of brick or block, and can have wooden ceilings. For these buildings, the exterior walls should last for two hours while the rest of the building should last one hour. Stores that have bricks or blocks on the outer walls fall within the category of type III-B, and can last for two hours; the rest of the building has no fire protection.
The types IV remain alone in this variation of building construction. This category includes what is called the heavy wood, because each must be at least 8 inches (20.32 centimeters) in diameter. This construction is often used for mills, and its exterior walls should last for two hours, while the structural framework should last for an hour. The floor, ceiling and roof have no rating, but each must be constructed of heavy timber.
Type V-A and B
This is the last in the types of building construction. V-A type buildings are built of wood that is considered protected by the outer walls, the structural frame, roof, floor and ceiling should last up to an hour. Most of the buildings that fall into this category are apartment buildings that have been built most recently. The V-B type includes most of the wooden family houses as well as garages. These buildings are considered unprotected, as there are often exposed within wooden structures.