Type 5 construction, also called Type V, is the most common building classification in the United States. It allows the use of any approved building material, including wood framing, and is the standard method used for single-family homes, small apartment buildings, and many commercial structures. The International Building Code (IBC) divides it into two subtypes, Type V-A and Type V-B, based on how much fire resistance the building provides.
How Type V Construction Works
Unlike higher construction types that require steel, concrete, or masonry for the structural frame, Type V places no restrictions on the materials used for walls, floors, or the structural skeleton. Wood framing is the most common choice because it is affordable and widely available, but builders can use any material that meets code. What distinguishes the two subtypes is entirely about fire protection.
Type V-A (protected wood frame) requires one-hour fire-resistant construction throughout. That means the structural frame, exterior walls, floors, ceilings, and roof assemblies must all be able to withstand fire exposure for at least one hour before failing. Builders achieve this with fire-rated drywall, intumescent coatings, or other approved coverings over the wood framing. No exposed wood is visible in a finished Type V-A building.
Type V-B (unprotected wood frame) has little or no fire-resistance requirement. The wood framing can be left exposed, and no special fire-rated coverings are mandated for most structural elements. This is the simplest and least expensive way to build, which is why it dominates residential construction.
Height and Area Limits
Because Type V buildings rely heavily on combustible materials, the IBC caps how tall and how large they can be. These limits vary by occupancy type (residential, commercial, office, etc.) and whether the building has an automatic sprinkler system, but the general maximums illustrate the scale these buildings are designed for.
Type V-A buildings can reach up to five stories above grade, with a maximum allowable floor area of roughly 46,000 square feet per floor for certain occupancy types. Type V-B buildings are more restricted, topping out at three stories with a maximum area around 22,000 square feet per floor. Installing a fire sprinkler system can increase both the allowable height and the permitted floor area, which is why most newer Type V-A apartment buildings include sprinklers.
These limits explain why you rarely see a Type V high-rise. Once a project exceeds four or five stories, the building code typically pushes designers toward Type III or Type I construction, which require noncombustible structural elements.
Where You See Type V Buildings
Type V-B is the default construction type for single-family homes, duplexes, townhouses, and detached garages across the country. If you live in a wood-framed house, it is almost certainly Type V-B. The exposed wood studs, rafters, and floor joists visible during construction (and sometimes left exposed in finished spaces like garages) are the hallmark of this subtype.
Type V-A is the go-to choice for newer apartment complexes, particularly the three- to five-story buildings common in suburban and urban infill development. Developers favor it because wood framing costs significantly less than steel or concrete, while the one-hour fire-rated assemblies satisfy code requirements for multi-family housing. Condominiums, assisted-living facilities, and small hotels also frequently use Type V-A construction. Mixed-use buildings with ground-floor retail and apartments above sometimes combine a Type I concrete podium on the first floor with Type V-A wood framing above, a design commonly called “five over one” or “podium” construction.
Fire Protection Differences That Matter
The practical gap between V-A and V-B comes down to how long the building’s structure holds up during a fire. A one-hour fire rating in a V-A building gives occupants and firefighters significantly more time to evacuate and respond before the structure is at risk of collapse. In a V-B building, an unprotected wood frame can begin to fail much sooner.
For this reason, the IBC requires Type V-A for buildings with more occupants or more stories. A three-story apartment building with 20 units, for example, would typically need V-A construction. A single-family home on its own lot, where fewer people are at risk and egress is straightforward, qualifies for V-B.
Builders working on Type V-A projects must pay close attention to fire-stopping, the process of sealing gaps around pipes, ducts, and wires that pass through fire-rated walls and floors. A single unsealed penetration can undermine the entire one-hour rating of an assembly, so inspectors scrutinize these details during construction.
Cost and Construction Speed
Type V construction is the least expensive of the five IBC construction types. Wood framing requires less specialized labor and equipment than steel or concrete, and materials are available at virtually every building supply outlet. A wood-framed building can go up faster as well, since carpenters can cut and assemble framing on site without cranes, welding, or curing time.
The tradeoff is durability and scale. Wood is more vulnerable to moisture, termites, and fire than steel or concrete, and the height and area limits mean Type V is unsuitable for large commercial buildings, hospitals, or anything taller than about five stories. For projects that fall within those limits, though, Type V remains the most cost-effective way to build.