Foundation width is the most impotent in any civil engineering structure as it determine the strength of a building and provide stability of a building or structure, For Proper calculation of a foundation you should consult a professional or a structural engineering the engineer will provide you the real and accurate date if you are a civil engineering student you can use this method for fast calculation or for thumb rule for trial and run in Structural software like in ETABS and Staad Pro etc. Calculating the length and width of the foundation is a critical step in ensuring the stability and structural integrity of any building. By taking into account the factors that affect foundation dimensions, and following the steps outlined in this article, you can determine the right foundation dimensions for your building.

Determining Foundation Width:

Example 01

let’s consider the example of a single-story residential Building on clay soil of Building 30 x 40 feet

Step 1: Determine the Soil Bearing Capacity The first step is to determine the soil bearing capacity.

In this example, let’s assume that the clay soil has a bearing capacity of 2,500 pounds per square foot.

Step 2: Calculate the Weight of the Structure The next step is to calculate the weight of the structure.

In this example, let’s assume that the home has a total weight of 200,000 pounds.

Step 3: Calculate the Required Foundation Width To determine the required foundation width,

we can use the following formula:

Width = Weight / (Bearing Capacity x Length)

Width = 200,000 / (2,500 x 30)

Width = 2.67 feet

Based on this calculation, we found that this foundation width of 2.67 feet would be sufficient to support the weight of the structure on the clay soil.

Example 02

let’s consider the example of a single-story residential Building on clay soil of Building 70 x 50 feet

Step 1: Determine the Soil Bearing Capacity The first step is to determine the soil bearing capacity.

In this example, let’s assume that the clay soil has a bearing capacity of 3,600 pounds per square foot.

Step 2: Calculate the Weight of the Structure The next step is to calculate the weight of the structure.

In this example, let’s assume that the home has a total weight of 400,000 pounds.

Step 3: Calculate the Required Foundation Width To determine the required foundation width,

we can use the following formula:

Width = Weight / (Bearing Capacity x Length)

Width = 400,000 / (3,600 x 70)

Width = 7.67 feet

Based on this calculation, we found that this foundation width of 7.67 feet would be sufficient to support the weight of the structure on this clay soil.

by this way you can calculate the width of a foundation, you can change the data of calculation from pound to Kg, Kn etc as per your preference and as per your need, you should know the total weight of a building and total bearing capacity of the soil you can prefer to our further posts about soil test, Soil test should be performed before any building or a structure is made because soil test provide us how much load a soil will resist or bear on it if building is made, for soil test you can refer to you country code for construction, like in india we use IS CODE for soil and other codes for building a structure.

one pound is equal to 0.453592 Kg and 1 Kg is equal to 9.81 N.