---
id:
aliases: []
tags:
  - destiny/permanent
  - type/encyclopedia
  - status/incomplete
  - authorship/original
  - topic/construction
title: IBC Construction Types
---
# IBC Construction Types

International Building Code (IBC) Section 602: Construction Classification
lists 5 major construction types based on fire ratings/materials.

## 5-Over-1 Construction

"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]] and 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 mid-rise office & Group R buildings.

* 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]],
with reduced fire-resistance requirements.

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

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

Common of [[pdi-building-types#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]].

## 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]].

* 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 garden 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.