Which construction type uses large-dimensioned lumber or laminated wood?

Type 4 construction, also known as Heavy Timber construction, primarily utilizes large-dimensioned lumber or laminated wood. This type of construction is characterized by structural elements made from heavy timber, which can provide enhanced fire resistance and structural integrity compared to standard wood frame construction. The larger dimensions of the timber allow it to withstand fire for a longer period without losing structural stability, making it a preferred choice for buildings that need both aesthetic appeal and durability.

The use of heavy timber can also contribute to a building’s acoustic insulation and overall design. It typically features fewer and larger interior spaces owing to the significant structural members, which can also help resist collapse compared to lighter wood materials.

In contrast, options such as Ordinary Construction (Type 3) typically use standard wood framing with less dimensional lumber, while Wood Frame (Type 5) construction utilizes lighter wood materials, and Fire Resistive (Type 1) construction utilizes non-combustible materials, reinforcing the distinct characteristics that define Heavy Timber construction.