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Blocking (
Blocking (dwang
In construction, a noggingFleming, Eric. ''Construction technology: an illustrated introduction''. Oxford: Blackwell, 2005. 123, 160. Print. or nogging piece (England and Australia), dwang (Scotland, South Island, New Zealand, and lower/central N ...
, nog, noggin, and nogging) is the use of short pieces of dimensional lumber
Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, wi ...
in wood framed construction to brace longer members or to provide grounds for fixings.
Uses
The primary purpose of blocking is to brace longer frame members such as wall studs against Euler's bending moment, which is a tendency tobuckle
The buckle or clasp is a device used for fastening two loose ends, with one end attached to it and the other held by a catch in a secure but adjustable manner. Often taken for granted, the invention of the buckle was indispensable in securing tw ...
under vertical compression. The intervals for the blocks are specified in the building code or as calculated by a structural engineer.
Blocking also resists the rotational movement, or twisting, of floor joist
A joist is a horizontal structural member used in framing to span an open space, often between beams that subsequently transfer loads to vertical members. When incorporated into a floor framing system, joists serve to provide stiffness to the s ...
s as they deflect under load. This may take the form of diagonal cross bracing
In construction, cross bracing is a system utilized to reinforce building structures in which diagonal supports intersect. Cross bracing is usually seen with two diagonal supports placed in an X-shaped manner. Under lateral force (such as wind or ...
, or ''herringbone'', bracing between floor joists. When solid blocks are used instead of diagonals it is called ''bridging'', ''block bridging'', ''solid bridging'' or ''solid strutting''. The illustration, right, shows solid blocking. Note how they are displaced alternately to allow nailing through their ends.
Blocking may also provide spacers or attachment points between adjoining stud walls, for example, where an interior and exterior wall meets, or at a corner where techniques such as the "three-stud corner with blocking" are used.
When correctly placed, blocking also provides ''grounds'' (also ''backing'' or ''back blocking'') for supporting the cut ends of wall claddings and linings or for attaching items such as cabinets
A cabinet is a body of high-ranking state officials, typically consisting of the executive branch's top leaders. Members of a cabinet are usually called cabinet ministers or secretaries. The function of a cabinet varies: in some countrie ...
, shelving, handrail
A handrail is a rail that is designed to be grasped by the hand so as to provide safety or support. In Britain, handrails are referred to as banisters. Handrails are usually used to provide support for body or to hold clothings in a bathroom or ...
s, vanity tops and backsplashes, towel bars, decorative mouldings, etc. Properly placed grounds make the second fixings easier once the walls are lined and they distribute the weight of heavy items across structural members. However, the locations required for use as grounds are dictated by the needs of the fittings and these often do not coincide with the locations required by the engineering specifications for use as bracing, consequently, the two forms may be present in the wall acting independently. When used only as grounds rather than as bracing, they are typically shallower. Simmons, H. Leslie. ''Olin's Construction: Principles, Materials, and Methods''. 9th ed. Hoboken: J. Wiley & Sons, 2011. Print.
Blocking is typically made from short off-cuts or to make use of defective, warped, pieces unsuited for use in longer lengths.
References
{{DEFAULTSORT:Blocking (Construction) Building engineering Carpentry