Construction Types Compared: How to Choose the Right Approach

Published on January 20, 2026 by Staff Writer

The construction industry in the United States and beyond relies on standardized classifications defined by the International Building Code (IBC). These may sound like jargon, but they drive extremely important project decisions. The one you choose affects your materials, how tall you can build, what fire-safety measures you need and the overall project timeline and budget.

In this guide, you’ll get a clear, plain-language breakdown of all five IBC types so you can choose one that works best for your project’s design, permitting and construction goals.

How the IBC Classifies Construction

IBC classification is based on:

• Fire ratings for major structural elements.
• Which elements of the structure are built with combustible materials.

These are the two main factors that drive the rules you must follow during planning and construction, such as allowable size, occupancy limits and required fire protection. They also matter in a real emergency. Firefighters do not approach a wood-frame building the same way they approach a concrete high-rise, because the risks and failure points differ.

Non-combustible materials, like steel and reinforced concrete, are generally more resistant to ignition and take longer to fail when exposed to heat, but they add cost and complexity. On the other hand, wood framing can keep projects moving faster and at a lower cost, but it also demands careful fire protection measures.

The Five Types of Building Construction

The IBC organizes construction into five types (I–V), each with subcategories A (protected) and B (unprotected). Type IV has three subcategories that are based on a combination of building height and fire resistance.

• Type I: Most fire-resistant
• Type II: Non-combustible with lower fire resistance
• Type III: Ordinary construction with non-combustible exterior walls
• Type IV: Heavy timber
• Type V: Fully combustible

Factors such as maximum heights, floor size and occupancy limits vary between each of these, though supplementary systems like sprinklers can enhance fire safety without changing the classification.

Type I: Fire-Resistive

Developed in response to devastating urban fires in the late 19th and early 20th centuries, this style emerged as cities grew taller and denser. Early skyscrapers in Chicago and New York revealed the limitations of wood and unprotected steel, leading engineers to adopt reinforced concrete and fire-protected steel framing to prevent catastrophic fire spread. These lessons shaped today’s most fire-resistant construction classification.

This classification of buildings relies on fully non-combustible structural elements such as reinforced concrete or protected steel, making it the safest option against fires. Interior structural elements, including columns, beams, floors and load-bearing walls, must meet strict fire-resistance standards, which differ by subcategory.

Compliance is measured in the length of time the material should last in a fire without breaking down or losing structural integrity.

• I-A: Three to four hours of fire resistance for primary frames, two to three hours for walls, two hours for floors.
• I-B: Slightly lower ratings, with two to three hours of fire resistance for frames and one to two hours for floors and walls.

High-rise buildings, hospitals, large office complexes and critical infrastructure are often built to this classification because of its exceptional safety and structural reliability. While it excels at outlasting any blaze and supporting heavy equipment, construction takes longer, and it is more expensive to build and maintain than other building types.

Type II: Non-Combustible Construction

This style is a solid fit for many everyday buildings, especially when maximum fire resistance is not required. Designs still rely on non-combustible materials, like steel and concrete, but do not take on the full fireproofing scope that comes with Type I.

In these buildings, the main structural system uses non-combustible materials, but the required fire-resistance ratings are lower. Depending on the subtype, some structural elements may have limited protection, or none at all.

• II-A: Structural elements typically have a minimum one-hour fire-resistance rating.
• II-B: Many structural components can be left unprotected.

You often see this kind of construction in strip malls, warehouses, light industrial buildings and schools, where balancing cost and construction speed matters a lot. However, these savings come a tradeoff. Unprotected steel can lose strength quickly under high heat, which can shorten the time a structure stays stable during a fire.

Type III: Ordinary Construction

This is the classic combination of masonry exterior with wooden interior framing seen in a lot of older main-street buildings, and it still shows up in new projects today. It’s a good compromise, creating more protection between neighboring buildings with a non-combustible exterior while keeping the interior framing affordable and easy to work with.

Type III buildings use non-combustible exterior walls paired with combustible interior framing material, most often wood or sometimes light-gauge steel, depending on the assembly. Fire-resistance requirements for the interior vary by subtype:

• III-A: Interior structural elements typically have one-hour fire-resistance ratings.
• III-B: Interior elements often have reduced ratings, or no required rating, depending on the specific component and design.

This classification is common in apartments, smaller commercial buildings and mixed-use projects, especially in denser areas. It offers a good balance of cost and safety, but it comes with a challenge.

In these buildings, concealed spaces in walls, floors and ceilings can let fire travel farther than you expect. Good fire-rated assemblies, careful detailing at penetrations and intersections and ample sprinkler coverage make a big difference in how these buildings perform.

Type IV: Heavy Timber Construction

This classification was first used in old warehouses and mills, where builders needed structures to take a beating and behave more predictably in a fire. Large wood timbers do not burn the same way small framing does. When exposed to heat, they char on the outside without damaging the core, allowing material to maintain its strength longer instead of failing quickly.

These buildings utilize large-dimension wood members for the interior framing, often paired with non-combustible exterior walls. Today, you may also see engineered mass timber, including cross-laminated timber (CLT), used to apply the same idea with newer technology.

Modern materials perform at greater heights, and with a smaller carbon footprint, than many traditional systems. These newer materials resulted in the adoption of three new subtypes that were introduced in 2021:

• IV-A: Up to 18 stories, with all mass timber members covered by non-combustible protection, such as gypsum wallboard, to achieve two- and three-hour fire-resistance ratings.
• IV-B: Up to 12 stories, allowing a limited amount of exposed mass timber, with assemblies designed to provide two-hour fire resistance.
• IV-C: Up to nine stories, with unprotected mass timber assemblies designed to meet a two-hour fire-resistance rating.

You’ll find this in renovated industrial buildings, offices, schools and specialty projects that value performance and a traditional architectural style.

Type V: Wood-Frame Construction

This is the common wood framing style found in most residential construction. Cheap, easily sourced lumber and simple, adaptable framing techniques make this the default choice in most areas.

In wood-frame buildings, combustible materials are allowed for all structural elements. Fire-resistance requirements depend on the subtype:

• V-A: Structure requires some level of fire protection.
• V-B: Structure has minimal or no fire-resistance requirements.

You’ll often see this style in single-family homes, townhouses and smaller apartment buildings. The big advantages are speed, cost and flexibility for remodels or future additions.

The main risk is fire spread, especially through concealed cavities in walls, floors and attics. For this reason, proper fire blocking, smoke detection and sprinkler systems are critical to occupant safety.

Selecting the Right Construction Type for Your Project

Picking a construction classification is not only about code categories and fire ratings. It’s also a practical choice that should match your building’s purpose, your site, your project planning and how you want to protect your structure over the long term. Use the factors below to narrow your options early, before design decisions lock you in.

Cost and Timeline

If speed and budget drive the project, Type V wood-frame is the simplest option for single-family homes, townhouses, small apartment buildings and small retail. Types I and II projects take longer and cost more upfront because concrete work, steel erection and fireproofing add time, coordination and inspections.

Durability and Safety

If you’re building something that needs high reliability, like a hospital or data center, Type I can be a strong fit because it offers top-tier fire resistance and structural stability. If you want a compromise between fire resistance and affordability, Types III and IV often fit the bill for mid-rise apartments, mixed-use buildings and small commercial parks where you want solid performance without the highest-cost system.

Location and Climate

Your region should influence your choice. In high-wind or hurricane-prone areas, Type I or II systems using steel or reinforced concrete perform well under extreme loads. In seismic zones, engineered timber and hybrid mass timber Type IV methods offer flexibility and energy dissipation when designed correctly.

Sustainability

If you want to reduce embodied carbon, mass timber options like CLT can be attractive, especially for mid-rise buildings. Concrete and steel typically carry higher embodied emissions, but long service life can help reduce the overall impact, depending on design, maintenance and the building’s total expected lifespan.

Aesthetic Goals

Building classification affects the feel of a space. Type IV heavy timber can support exposed wood interiors that many people prefer in schools, offices, and retail spaces. Types I and II support large open spans and clean, modern layouts that work well for offices, cultural spaces and large public buildings.

Connect Building Types to Real Work

If you want a stronger grasp of how building types connect to real plans and work, check out the Overview of Building Trades course. You will get a clear overview of trade skills, construction sequencing and plan basics so you can make smarter decisions early.