A load-bearing wall or bearing wall, is one in which a wall of a structure bears the weight and force resting upon it, conducting the vertical load from the upper structure to the foundation. A bearing wall is opposed to a curtain wall, which uses the strength of a sub-wall to bear the weight of the curtain such as the brick facade on a skyscraper, and superstructure, usually a steel frame, to carry the weight of the floors and walls inside the curtain walls protection. The materials most often used to construct load-bearing walls in large buildings are concrete, block, or brick.
Load-bearing walls are one of the earliest forms of construction.
The development of the flying buttress in Gothic architecture allowed structures to maintain an open interior space, transferring more weight to the buttresses instead of to central bearing walls. Notre Dame Cathedral, for example, has a load-bearing wall structure with flying buttresses.
The birth of the skyscraper era, the concurrent rise of steel as a more suitable framing system first designed by William Le Baron Jenney, and the limitations of load-bearing construction in large buildings led to a decline in the use of load-bearing walls in large-scale, commercial structures.
Depending on the type of building and the number of stories, load-bearing walls are gauged to the appropriate thickness to carry the weight above it. Without doing so, it is possible that an outer wall could become unstable if the load exceeds the strength of the material used, potentially leading to the collapse of the structure.
In housing, bearing walls in the most common light construction method "platform framing", and each sit on wall sill plates which are mated to the lowest base plates, the two together making up a double height 2x4 or 2x6 laid horizontally atop one another. The sills are bolted to the masonry or concrete foundation.
The top plate or ceiling plate is the top of the wall, which sits just below the platform of the next floor (at the ceiling). The base plate or floor plate is the bottom attachment point for the wall studs. Using a top and bottom plate, walls can be constructed laying down, allowing for end nailing of the studs between two plates. The finished wall can then tipped up vertically into place atop the wall sill. This improves accuracy and shortens construction time, while providing for a stronger wall.
Due to the immense weight of skyscrapers, the base and walls of the lower floors must be incredibly strong. Pilings are used to anchor the building to the bedrock underground. For example, the Burj Khalifa, the world's tallest building as well as the world's tallest structure, uses specially treated and mixed reinforced concrete. Over 45,000 m3 (58,900 cu yd) of concrete, weighing more than 110,000 tonnes (120,000 ST; 110,000 LT) were used to construct the concrete and steel foundation, which features 192 piles,with each pile is 1.5 meter diameter x 43 meter long buried more than 50 m (164 ft) deep.