---
tags:
  - topic/construction
  - type/encyclopedia
title: IBC Construction Types
---
# IBC Construction Types

[[ibc_s0602|IBC Section 602: Construction Classification]]
lists 5 major construction types based on fire ratings/materials.

> [!info] 5-Over-1 Construction ^5-over-1
>
> "5-over-1" construction denotes a building
> with levels of combustible construction
> above levels of non-combustible construction.
>
> buildings with two non-combustible levels (5-over-2)
> and Type III upper floors (3-over-1)
> are also common,
> though "5-over-1" denotes the general practice.

## Type I: Fire Resistive Non-Combustible

Building elements are noncombustible[^1]

[^1]: Defined as passing the test procedures
    for defining combustibility of elementary materials
    set forth in ASTM E 136

* Concrete, masonry, noncombustible steel

### Type I-A: Protected Fire-Resistive Non-Combustible

Common of [[pdi-building-types#High Rise|high rise]]
and [[ibc-occupancy-classifications#Group I Institutional|Group I]] occupancies.

* 3hr Exterior Walls
* 3hr Structural Frame
* 2hr Floor/Ceiling Assembly
* 1.5hr Roof Protection

### Type I-B: Unprotected Fire-Resistive Non-Combustible

Common of [[pdi-building-types#Mid Rise|mid rise]] office
and [[ibc-occupancy-classifications#Group R Residential|Group R]] occupancies.

* 2hr Exterior Walls
* 2hr Structural Frame
* 2hr Ceiling/Floor Separation
* 1hr Ceiling/Roof Assembly

## Type II: Non-Combustible

Same materials as [[#Type I Fire-Resistive Non-Combustible|Type I]],
with reduced fire-resistance requirements.

Common of [[pdi-building-types#Mid Rise|mid rise]] buildings.

### Type II-A: Protected Non-Combustible

Common of [[pdi-building-types#High Density|high density]],
including dormitory buildings.

* 1hr Exterior Walls
* 1hr Structural Frame
* 1hr Floor/Ceiling/Roof Protection

### Type II-B: Unprotected Non-Combustible

Common of [[pdi-building-types#Commercial|commercial]].

## Type III: Combustible

Also known as "ordinary" construction.

Exterior walls are of noncombustible materials.
Interior building elements may be combustible.

### Type III-A: Protected Combustible

Common of [[pdi-building-types#High Density|high density]].

* 2hr Exterior Walls
* 1hr Structural Frame
* 1hr Floor/Ceiling/Roof Protection

### Type III-B: Unprotected Combustible

Common of "warehouse" districts of older cities.

* 2hr Exterior Walls

## Type IV: Heavy Timber

Also known as "mill" construction.

Exterior walls are of noncombustible materials.
Interior building elements are of solid or laminated wooden members
with a minimum nominal dimension of 8 inches
without concealed spaces.

* 2hr Exterior Walls
* 1hr Structural Frame or Heavy Timber Heavy Timber Floor/Ceiling/Roof Assemblies

## Type V: Wood Frame

Construction materials are of any allowed by code,
combustible or noncombustible.

Common of [[pdi-building-types#Garden Style|garden style]] or above podiums

### Type V-A: Protected Wood Frame

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

* 1hr Exterior Walls
* 1hr Structural Frame 1hr Floor/Ceiling/Roof

### Type V-B: Unprotected Wood Frame

Common of single family homes.
