Building structures can generally be classified into two broad categories based on the way loads are transferred- load bearing structures and framed structures. Load bearing structures were the most commonly used typology until the late 19th century, when framed structures were first created due to the advent of steel, glass and concrete in construction. Read on to learn more about the timeless technique of load bearing construction.
What is a Load Bearing Structure?
Structures where the building loads are transferred directly onto walls instead of columns or other vertical structural elements are termed as load bearing. Load bearing walls, as the name suggests, help in bearing and transmitting the loads of the structure, a function which would otherwise be performed by columns in a framed structure. Each wall serves as a structural element that assures the stability of a building.
Elements of a Load-Bearing Structure
- Roofs/ floors
Apart from shelter and usable horizontal spaces, roofs and floors provide horizontal surfaces for the uniform distribution of different types of loads that affect any building. Although these are generally present in the form of slabs, they can also be designed as vaults, arches or pitched roofs. However, one of the most crucial functions of any type of roof or floor is the transfer of loads to other elements.
- Beams
Beams form horizontal elongated elements that collect load from roofs and floors and then transfer them to the succeeding elements in a structure. These however, are not a crucial element in loading bearing structures, where beams can be eliminated to enable roofs to directly rest on load bearing walls.
- Walls
Walls form the major component of load bearing structure. They are vertical elements which bear the weight of all the elements above them, such as beams and roofs, before transmitting it to the floor or foundation below it.
- Foundation
A building foundation forms the base of the building which rests directly on soil and transmits load onto it, responsible for the building’s overall stability. Load bearing structures generally do not require deep foundations.
Material Options for Load Bearing Construction
Numerous material options are available for the construction of load bearing walls in the current era. These can be used individually or in combination with other such materials to create composite structures.
- Brick Masonry
Brick masonry is the most commonly used method for the construction of load bearing walls, especially for residences. Brick walls can be constructed solidly or with cavities, but need to have a minimum thickness of nine inches to be able to bear loads and transmit them effectively.
- Stone
Stone is one of the oldest materials used for load bearing construction, especially for temples and other public buildings. Multiple types of stone such as limestone, sandstone and granite can be used to create structures that have extremely high durability and resistance to environmental conditions.
- Concrete
The most frequently used material in modern construction, concrete can be used to create wall panels that are precast or in-situ retaining walls. Easy to construct and highly durable, this is a relatively quick way to create load bearing structures.
- Rammed Earth
A material created by the compaction of soil found in the construction site itself, rammed earth is a sustainable option for executing load bearing structures. However, rammed earth walls generally cannot bear excessive loads (such as in buildings with more than two storeys) and pose difficulties for routing of electrical and plumbing conduits.
Apart from these conventionally used materials, a lot of new innovative materials such as metal panels, 3D printed wall and roof panels and structural glass are increasingly being used for constructing load bearing structures, offering versatile design options.
Advantages of Load Bearing Structures
Although not frequently used in modern construction, load bearing structures encompass a time-tested methodology which has survived centuries of architectural revolution due to the numerous inherent advantages that it offers.
- Cost
Reduced dependency on materials and labour for concrete/ steel/ other columns, along with the general usage of local materials like brick and stone result in the reduction of overall cost.
- Labour
Availability of specialised labour for the erection of columns is not required for load bearing construction, enabling swift and able construction with local and simple tools, techniques and labour.
- Uniformity
Load bearing walls are generally made of a single material, the uniformity of which allows better finishing, especially for plastered finishes. The absence of joints between different materials, such as concrete columns and brick walls, helps mitigate the probability of cracks.
- Durability
Load bearing structures are highly durable due to enhanced resistance to adverse weather conditions and fire, combined with high structural stability.
Disadvantages of Load Bearing Structures
Although the construction methodology of load bearing structures has survived multiple centuries, it has certain intrinsic disadvantages that limit its usage in modern construction.
- Decrease in Carpet Area
Load bearing structures generally feature walls that are thicker than conventional framed structures, resulting in reduced carpet area and usable space. This can also reduce the commercial value of built structures for selling or renting.
- Time Consumption
Framed structure construction allows erection of columns and slabs with simultaneous erection of walls in lower floors. This is not possible with load bearing structures, where walls must be completely built before the successive roof or floor slab can be erected, resulting in increased consumption of time for building completion.
- Decreased Flexibility
Load bearing structures generally require walls of one floor to align with walls of every other floor. Excepting multi storeyed residences with repetitive unit plans, this can be a major disadvantage in buildings due to decreased flexibility and freedom in design.
- Additions/ Changes
Framed structures allow removal or changes in partition walls to accommodate changing or growing needs of building users. However, this is not possible with load bearing structures as any change in the load bearing elements can result in structural instability and failure.
- Restricted Building Height
Construction of high rise buildings with a load bearing structure is generally not probable and preferable, due to excessive wind loads and increased time consumption for completion.
Load Bearing Structure Design
The design of load bearing structures requires careful considerations and calculations of the various types of loads that affect buildings. Specific site factors such as climatic conditions, soil type and load bearing capacity also play a crucial role in opting for load bearing structures. Although such structures are often built in rural areas without external consultation, it is strongly recommended to take the expert advice of structural engineers, architects and contractors to ensure stable and durable construction. Contact Brick & Bolt today to construct your dream home based on planning by experts, accompanied with managed end-to-end construction processes.