Building construction type definitions

Commonly found in high-rise buildings and Group I occupancies

3 Hr. Exterior Walls*

3 Hr. Structural Frame

2 Hr. Floor/Ceiling Assembly

1 1⁄2 Hr. Roof Protection

Commonly found in mid-rise office & Group R buildings

2 Hr. Exterior Walls*

2 Hr. Structural Frame

2 Hr. Ceiling/Floor Separation

1 Hr. Ceiling/Roof Assembly

Commonly found in newer school buildings

1 Hr. Exterior Walls

1 Hr. Structural Frame

1 Hr. Floor/Ceiling/Roof Protection

Most common type of non-combustible construction used in commercial buildings.

Building constructed of non-combustible materials but these materials have no fire resistance.

Also known as "ordinary" construction with brick or block walls and a wooden roof or floor assembly which is 1 hour fire protected.

2 Hr. Exterior Walls*

1 Hr. Structural Frame

1 Hr. Floor/Ceiling/Roof Protection

Also known as "ordinary" construction; has brick or block walls with a wooden roof or floor assembly which is not protected against fire. These buildings are frequently found in "warehouse" districts of older cities.

2 Hr. Exterior Walls*

No fire resistance for structural frame, floors, ceilings, or roofs.

Also known as "mill" construction; to qualify all wooden members must have a minimum nominal dimension of 8 inches.

2 Hr. Exterior Walls*

1 Hr. Structural Frame or Heavy Timber

Heavy Timber Floor/Ceiling/Roof Assemblies

Commonly used in the construction of newer apartment buildings; there is no exposed wood visible.

1 Hr. Exterior Walls

1 Hr. Structural Frame

1 Hr. Floor/Ceiling/Roof

Examples of Type V-N construction are single family homes and garages.

They often have exposed wood so there is no fire resistance.

* Note exceptions in the building code for fire resistance ratings of exterior walls and opening protection.