How Much Quantity of Steel required per Sq. Feet. of RCC Slab

Are you a civil engineer or contractor or Raj Mistry? Do you know how much steel is required (steel requirement of slab) for per square feet slab section?

Here, we are discussing about the simple and the easiest way to calculate the amount of steel as per IS code.

In RCC slab casting process, quantity of steel required for slab section is dependent on thickness of slab, and thickness of slab dependent upon the types of building structures like residential buildings or low-rise buildings or construction of high-rise buildings.

Steel required per square feet slab also dependent on load bearing structure and we know that the slab will transfer its dead load and live load to the beam, via beam and column, the load will transfer to footing and finally footing transfer the same amount of load into the ground.

There are two types of Steel used in roof slab i.e. Main bar & Distribution bar.

Main bar: – Main reinforcement are used in the shortest span of slab that’s why it is also known as short bar; generally main reinforcement is used at the bottom of slab having higher diameter of steel.

Distribution bar: – Distribution reinforcement is used in the longer span of the slab that’s why it is also known as a long bar, generally, distribution reinforcement is used at the top of the slab having a lesser diameter or same diameter of steel as per types of the building structure. Actually, the distribution bar is aligned as the cross direction of the main bar that’s why it is also known as cross bar.

Thumb Rule for using reinforcement in RCC slab:-
Generally, the Thumb Rule for reinforcement in RCC slab construction is ranging between 75 Kg to 80 kg per cubic meter of concrete (wet volume of concrete) or 1% of concrete volume (7850 kg per cubic meter) of the RCC slab.

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Now we are going to share with you the calculation process of slab having different thickness.

Here we take area of slab is 1 square feet and thickness is 4 or 5 or 6 inches for calculation.

For 4-inch thickness:

(steel requirement of slab)

Wet volume of concrete is equal to multiplication of area and thickness of slab.

So, 1 sq ft × (4/12) ft = 0.334 cubic ft, so wet volume of concrete equal to 0.334 cubic ft. (Here, 4-inch converted into ft by dividing with 12.)

By converting it into cubic meter we get, 0.334/35.3147 = 0.00944 cubic meter where 1 cubic meter = 35.3147 cubic ft.

So, wet volume of concrete is 0.00944 cubic meter.

As per Thumb rule for Steel required for RCC slab is ≈ 80 kg/m3, then quantity of steel required for 1 sq ft (0.00944 cubic meter) RCC slab is equal to = 80 × 0.00944 = 0.755 Kg.

0.755 Kg of steel are required for per sq ft of 4-inch thick RCC slab.

For 5-inch thickness:

(steel requirement of slab)

1 sq ft × (5/12) ft = 0.417 cubic ft, so wet volume of concrete equal to 0.417 cubic ft. (Here, 5-inch converted into ft by dividing with 12.)

By converting it into cubic meter we get, 0.417/35.3147 = 0.0118 cubic meter where 1 cubic meter = 35.3147 cubic ft.

So, wet volume of concrete is 0.0118 cubic meter.

As per Thumb rule for Steel required for RCC slab is ≈ 80 kg/m3, then quantity of steel required for 1 sq ft (0.0118 cubic meter) RCC slab is equal to = 80 × 0.0118 = 0.944 Kg.

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0.944 Kg of steel are required for per sq ft of 5-inch thick RCC slab.

For 6-inch thickness:

(steel requirement of slab)

1 sq ft × (6/12) ft = 0.5 cubic ft, so wet volume of concrete equal to 0.5 cubic ft. (Here, 6-inch converted into ft by dividing with 12.)

By converting it into cubic meter we get, 0.5/35.3147 = 0.01416 cubic meter where 1 cubic meter = 35.3147 cubic ft.

So, wet volume of concrete is 0.01416 cubic meter.

As per Thumb rule for Steel required for RCC slab is ≈ 80 kg/m3, then quantity of steel required for 1 sq ft (0.0118 cubic meter) RCC slab is equal to = 80 × 0.01416 = 1.133 Kg.

1.133 Kg of steel is required per sq ft of 6-inch thick RCC slab.

Conclusion: This is how we can easily calculate and use the quantity of steel as per their types of building and requirement. With this calculation method, an owner or a contractor of a building/ construction can easily find out the quantity of steel required for their RCC slab casting. This method will help to assume the cost of construction if we know the average costing of cement, sand, aggregate, and labour cost. We will discuss the quantity of cement, sand, and aggregate for the RCC slab in our next article. Stay tuned for that.

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Jyotirmay Maity

Jyotirmay Maity is a B.Tech Civil Engineer with more than 8 years of experience in various Civil Engineering field i.e. Geosynthetics, Building Design, Road, Draftsmanship, and Project Management. He is the founder of this blog and his motto is to share his experiences with you. You can connect with him via mail to [email protected]

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