Blocking is a small but vital part of any construction project, whether it’s a home or a commercial building. Blocking can play many roles that vary from something as important as structural stability or as minor as making art easier to hang on a wall.
What is blocking in construction?
Blocking refers to a piece of lumber or other material installed in between the framing members of a wall, floor, or ceiling. The blocking generally serves two purposes:
- It provides structural stability or
- Serves as a material to fasten other objects to
Structural uses
Blocking is often installed between larger building components, such as floor joists, rafters, and studs, to provide additional support and prevent movement. In a floor, for example, the floor joists have a tendency to twist under load, so blocking or bridging is used to help prevent the twisting from occurring.
Blocking also helps to transfer loads and forces from one structural element to another.
Where there are smaller penetrations through a roof or wall, blocking might be used to help support the edges of the floor or roof substrate, with the added bonus of providing a material secure the penetrating object to.
Material to fasten other objects to
Blocking is also installed under a finish material, like drywall, to make it easier to install items that need more structural support than just a drywall anchor.
It’s particularly important for components that provide safety to the occupants of the building. For example, blocking should be installed at handrail supports or grab bars when they can’t be directly fastened to the studs.
It’s also useful for heavier items that need to carry a large load. For example, using blocking where shelving will be installed, or behind the drywall for kitchen cabinets. The blocking provides a strong substrate to fasten to that isn’t restricted to the locations of the studs.
Materials used for blocking
The most common materials used for blocking in construction include:
Wood: Blocking made of lumber is commonly used in construction due to its strength, affordability, and ease of installation.
Metal: Blocking made of metal, usually sheet metal or steel studs, are used in commercial construction due to its high strength, durability, and because it’s non-combustible.
Engineered wood products: These include materials like oriented strand board (OSB) and plywood, which are commonly used in residential construction due to their strength and affordability.
