Type B Construction: What It Is, Where It's Used, and Why It Matters

When you hear Type B construction, a building classification defined by fire resistance ratings and material limits under international building codes. Also known as Type IIB construction, it's the go-to choice for mid-rise offices, retail spaces, and light industrial buildings where you need durability without the cost of full steel framing. Unlike Type IA, which uses non-combustible materials throughout, Type B lets you use wood framing—but only if it’s protected by fire-resistant drywall or other barriers. This makes it a smart middle ground: safer than wood-frame residential builds, cheaper than all-steel commercial towers.

Type B construction fire resistance, the ability of building elements to contain flames and limit heat spread for a set time is its core feature. Walls, floors, and ceilings must hold up for at least one hour under fire test conditions. That’s why you’ll often see 5/8-inch Type X drywall on steel studs in office buildings, or protected wood trusses in a two-story strip mall. It’s not about being fireproof—it’s about giving people time to escape and firefighters time to respond. This directly ties into building codes, local and national regulations that dictate how structures are built for safety, which vary slightly by region but always require Type B to meet minimum fire performance standards.

Many mixed-use buildings combine Type B with other types. Think of a ground-floor retail space (Type B) with apartments above (Type V wood-frame). That works—but only if there’s a proper fire separation wall between them. Cutting corners here isn’t just risky, it’s illegal. Insurance companies and inspectors watch for this. If you’re planning a renovation or new build, knowing whether your project falls under Type B helps you pick the right materials and avoid costly delays. You don’t need to be an architect to understand this, but you do need to ask the right questions.

What you’ll find below are real-world examples and clear explanations about how Type B construction shows up in projects—from warehouses to small business centers. You’ll see how it compares to other types, what materials are allowed, and why some builders choose it over others. Whether you’re a homeowner, contractor, or just curious about how buildings stay safe, these posts give you the facts without the jargon.