The international building code defines five types of construction. In Austin, there are also seven building elements used in projects. Before launching a build in Austin, Texas, it is essential to know the different construction types and elements, the terminology used, and the regulations associated with each building code.
Here is an overview of different elements used in Austin construction, the type of construction identified in IBC, and what they mean in Texas building projects.
An Introduction to Construction Types and Building Elements
First, let’s talk about the difference between elements and types. The two refer to different things and are used for different purposes, but people sometimes confuse the terminology.
Construction types revolve primarily around materials used and their fire resistance ratings. At the same time, the other classifications categorize the exterior and interior structural elements included in a project.
Building code sets different fire protection requirements for each of the seven elements. A fire-resistance rating is given by hours- a.k.a. how many hours minimum it can be exposed to fire without succumbing. Each element in the Austin building code has its requirement that determines what type of construction is required for the build.
What Are the Five Construction Types in Austin?
Let’s begin with the five construction types in international code. There are further breakdowns within some categories divided by Type A and Type B. This specifies whether a structure is protected or unprotected.
The type of construction required for Type A and Type B in each division depends on several things, including the structure’s height, whether the building is commercial or residential, and ventilation systems.
What type of construction a building element requires, and the hourly fire resistance rating it needs to pass code in Austin is detailed to keep everyone as safe as possible.
Here is an overview of each construction type and when it is used.
Type I: Fire Resistive
The most advanced level of construction is Type I Fire Resistive. This means a structure can withstand high heat and fires for a long time without collapsing or burning.
Type I construction is essential in any building or structure over 75 feet tall, including high-rise apartments, multi-story buildings, and commercial offices or hotels. It offers the most protection against spreading fire and makes it easier for firefighters to do their job.
In many (but not all) Type I buildings, pressurized HVAC systems are in place to enhance the slowing of fire spread, especially in stairwells, to make evacuation easier.
Generally, Type I buildings can withstand fire for at least two hours, often three to four hours without collapsing. In the Austin building code, a Type IA structure must have at least a three-hour rating on the frame and all bearing walls.
Type II: Non-Combustible
One step down from fire-resistive is noncombustible, or Type II construction. The materials used in Type II buildings are similar to Type I in that they have metal and concrete cores that can withstand high temperatures for a decent time. They are labeled noncombustible rather than fire-resistive because they have not been treated with an outer coating.
A building project labeled Type II offers more flexibility in choosing materials but less fire resistance (usually around one hour). It is commonly found in big stores, modern school buildings, commercial malls, or buildings under 75 feet tall.
Type III: Ordinary
Another name for Type III construction is brick and joist structures because they follow the standard procedures and use the standard materials widely found in the construction industry. Unsurprisingly, ordinary construction (Type III construction) is the most common construction type.
It is used in most residential buildings, older schools, and average-sized buildings around you.
One of the essential things to understand about fire resistance in Type III buildings is that only the exterior is made using fire-resistant materials. The goal here is to stop the spread of fire between buildings, but if it breaks out inside, it is unlikely that the spread will be stopped. Part of the reason is that there are few restrictions on the types of ventilation that can be used.
Most interior sections of Type III buildings have zeros for fire resistance ratings, but the exterior walls (in Austin) should have a two-hour rating to be up to code.
Type IV: Heavy Timber
Heavy timber construction is much less common nowadays but was popular up until the 1960s. It is pretty easy to spot a Type IV construction because of the apparent presence of large lumber beams- think old churches and farmhouses.
Despite being made primarily from wood, Type IV buildings are surprisingly resilient against flames. Part of the reason is the sheer size and thickness (it must be at least six to eight inches thick to meet code requirements). It means collapse takes much longer, with many Austin Type IV buildings having a two to three-hour fire resistance rating.
Type V: Wood Frame
Type V buildings are the least fire-resistant of them all. These are wood-framed buildings and are the only category that allows combustible materials to be used in the exterior walls. Most Type V buildings, including single-family homes and small local stand-alone shops, are tiny.
Because they are made from solid or laminated wood (often exposed wood), there is no protection against flames. However, there is a division between Type V A and Type V B construction. Type V A construction requires fire-rated building materials in the supporting walls, floors, and roofs, but Type V B does not.
Nowadays, Type V A is rarely found, and most Type V buildings come under Category B, which allows combustible exterior walls, interior walls, and significant structural elements. Most buildings in this category will succumb to fire very quickly.
What Are the Seven Building Elements in Austin?
Now, let’s talk about building elements. Austin building code divides construction types into seven categories, each with a specific fire resistance requirement that helps those managing construction projects understand the materials allowed in the exterior and interior elements.
Primary Structural Frame
The primary structural frame is the core of any build. Depending on the type of construction, a wood-framed build may be acceptable, but in others, noncombustible materials must be used.
Exterior Bearing Walls
This refers to the outside walls that support the structure- including the upper floors and the roof. Noncombustible exterior walls are essential in every construction except Type V.
Interior Bearing Walls
Moving inside, the interior walls that help support and bear weight generally have a higher required fire-resistance rating than those that do not.
Non-Bearing Walls and Partitions (Exterior)
Outside walls that bear no weight (an added porch, for example) do not have the same strict code, but some requirements still depend on the walls’ size and location.
Non-Bearing Walls and Partitions (Interior)
Walls and partitions inside a building are not required to have fire protection in any construction in Austin.
Floor Construction (and associated structural members)
Depending on the construction type, anything related to the floor structure and finish may require up to two hours of fire protection.
Roof Construction (and associated structural members)
Roofs are usually required to resist fire for at least one hour under the Austin code.
The types of construction required come down to the level of fire protection they need. Every building element has its specification that changes based on its type, and a construction manager is responsible for ensuring code is met at every point.