Footings shall be a minimum of 8 inches by 24 inches (203 mm by 610 mm) for houses two and one-half stories and less. The footings for a three-story building shall be 10 inches by 24 inches (254 mm by 610 mm).
As far as I know, as a thumb rule, a foundation must be at least one metre (3.5 feet) deep for a one-story building in medium clay soil, four feet (1.2m) for a two-story building, five feet (1.5m) for a three-story building, six feet (1.8m) for a four-story building, and seven feet (2.1m) for a five-story building.
Among the types of foundations being used today, using 3-story house's strip footings is considered the best solution to help the building withstand load. However, during the construction process, attention also needs to be paid to safety factors.
You can look up the recommended footing size, based on the size and type of house and the bearing capacity of the soil (see the table above). As you can see, heavy houses on weak soil need footings 2 feet wide or more. But the lightest buildings on the strongest soil require footings as narrow as 7 or 8 inches.
How deep and wide must my house footings be? That depends on the number of stories the house will be. A minimum of 12”inches deep for all footings and the width will be determined by the amount of stories, 12” inches for a single story, 15” inches for a two story and 23” inches for a three story.
For a 3-storey (G+2) house, using standard 9″ thick walls, it is recommended the minimum size of the Foundation for footing should be 5'× 5'× 5′ (1.5m x 1.5m×1.5m) with respect to length, breadth and depth. How deep is the foundation of a 4 story building ?
To determine the size of the footing, a simple formula is used: Structural Load (lbs) / Soil Capacity (psf) = Footing Surface Area Required (sq. ft.)
5 feet to 6x6 feet footing size. Similarly, a 2-storeyed one requires 5x5 feet and single storied will need 4x4 feet footing size. In case if the soil type is not provided for the design, it is essential to mention the footing sizes.
The minimum footing thickness should not be less than the distance the footing extends outward from the edge of the foundation wall, or 6 inches, whichever is greater.
The footing is what's actually in contact with the ground, while the foundation is the structure that transfers the load to the earth. A simple way to visualize the difference when comparing it to the human body would be to view the footing as the actual feet of the legs and the foundation being the legs themselves.
Reinforcing the foundation is crucial for maintaining the structural integrity of a 3-storey building. The reinforcement process involves the use of steel bars, mesh, and other materials to enhance the foundation's ability to withstand loads, resist cracking, and prevent settlement.
Poured concrete is the strongest type of foundation for a house. Concrete is incredibly strong and durable, and it can be poured into any shape. This makes it ideal for supporting the weight of a house. Block foundations are also very strong, but they are not as flexible as poured concrete.
In general, the standard beam size for a G+2/3-storey residential building is at least 12 × 12 in inches, or 300 × 300 in mm.
Required Footing Sizes
In most cases, a house should have a minimum footing of 12 inches wide by 12 inches deep, with foundations that are 8 to 10 inches thick. This should be enough to support house weight and resist lateral soil and water pressure.
Therefore, a 3-story building is often approximately 30 - 33 feet (9 - 10 meters + Parapet + Plinth height) tall. However, some sources suggest that 33.5 - 35 ft. height is considered the average and comfortable measurement for a three-story building.
to measure the length, width, and thickness of the footing in metres. Then, multiply those measurements together to get the cubic metre volume of the beam. To calculate the amount of steel needed for the footing in kilograms, multiply the volume of concrete footing by 0.5% and the density of steel (7850 kg/m3 ).
Even the best contractors occasionally have to build on a sloppy footing. Ian Geisler, a noted ICF expert who has worked on hundreds of projects across the continent, says that realistically a perfect footing is anything within ¼” of level. “If it's within ½”, then it's workable,” he writes.
Calculate footing size by determining vertical and horizontal loads, assessing soil bearing capacity, and selecting an appropriate type. Divide net load by soil bearing capacity to find footing area. Check local codes, consider settlement, and iterate as needed.
You can look up the recommended footing size, based on the size and type of house and the bearing capacity of the soil. As you can see, heavy houses on weak soil need footings 2 feet wide or more. But the lightest buildings on the strongest soil require footings as narrow as 7 or 8 inches.
Column footing size for three floor or storey (G+2) building: With regards to three floor or storey (G+2) house or in just 3 floor building, standard guideline, utilizing conventional 9″ thick walls, it is suggested that the size of column footing must be 5' × 5' × 5′ (1.5 m x 1.5 m × 1.5 m) with regards to isolated ...
Footings shall be a minimum of 8 inches by 24 inches (203 mm by 610 mm) for houses two and one-half stories and less. The footings for a three-story building shall be 10 inches by 24 inches (254 mm by 610 mm).
The minimum footing width is 12 inches. Calculation of footing size may result in a smaller footing but the code requires a minimum 12 x 6 or 12 inches wide and 6 inches deep footing. In addition, tables are based on the type of foundation.