How much steel required for 700 sq ft slab at 4″, 5″ & 6″ thickness
The amount of steel required for a concrete slab depends on various factors, including the dimensions, thickness, and the type of load it needs to support. To estimate the amount of steel required, you’ll need to calculate the steel reinforcement in terms of weight (usually in kilograms or pounds) per square foot.
Typically, for residential construction, you might use #4 (1/2 inch) or #5 (5/8 inch) rebar spaced at 12 inches on center for a 4-inch thick slab and closer spacing for a 5-inch thick slab.
Rebar is short form of reinforcing bar, it is steel bar or Steel wire provided as tension bar, used in reinforced concrete structure like column, beam and slab of house construction and it also used in reinforced masonry structure. It is used to increase the strength of concrete structure.
Thumb rule for steel in Rcc slab is about 1 percentage of steel in concrete. Steel calculation formula in slab: steel quantity = Volume of Concrete x Density of Steel x % of Steel. For example, if a volume of concrete 1 m3 for a slab. Approximately Steel requirement = 1 x 7850 x 1% = 78.5 Kg/m3. So minimum quantity of steel required for 1m3 concrete slab is 78.50 Kg.
The required Steel for the RCC slab is 78.5 kgs/m3, then the quantity of steel required for 100 sq ft ( 1.18 m3) RCC roof slab is equal to = 78.5 ×1.18 = 92.63 Kgs. 92.63 Kgs steel quantities are required for 100 sq ft 5-inch thick RCC roof slab.
Actual Steel calculation is based on as per design but if design is not given then Steel calculation is based on Thumb Rule on experience basis. In roof slab reinforcement we provide there is a two types of Steel bar used main bar and cross bar :-
The main bar, also known as the bottom reinforcement, provides support to resist tensile forces in a slab, while the cross bar, or top reinforcement, helps distribute loads and prevent cracking. Both play crucial roles in enhancing the structural integrity of a concrete slab.
Main bar is also called as shortest span bar usually used at bottom of slab having spacing 4 inch between the two bar. Main bar is also called tension Steel because it is provided in tension zone of roof slab in bottom having tensile strength of steel is enough yield strength and ultimate tensile strength.
We should use higher tensile steel in main bar Fe550D. sufficient amount of main bar used in shorter direction having 10 mm or 12 mm dia of Steel bar according to roof slab reinforcement.
Cross bar is also called as longer span bar or distribution bar or cross bar mainly used at top of the main bar in compression zone of slab, cross bar usually dia of 8mm or 10 mm bar Steel bar used in longer direction according to roof slab reinforcement.
The main bar spacing in a roof slab, often referred to as the reinforcement or rebar spacing, depends on various factors such as the design requirements, load conditions, and structural codes. Commonly, the main bar spacing in roof slabs can range from 100mm to 300mm, but this can vary.
According to Indian standard Rcc concrete roof slab thickness in residential building construction is 4 inches (100mm). Use of 5″ to 6″ (125mm to 150mm) is recommended if the concrete will receive occasional heavy loads.
Generally Thumb Rule for Steel in RCC slab construction is ranging between between 80 kg to 90 kg per cubic metre per wet volume of concrete of RCC slab. On average, 85kg/m3. More simple formula for residential flat, steel required in kg = area of slab in sq ft. This will give maximum limit. You can take 85% of it for normal residential building with 3 meter span.
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For office, school building, steel may increase marginally due to live load condition. For multistorey buildings, steel will increase further. With increase in span and load, thickness of slab will also increase.
How to calculate steel required for 700 square feet slab
To calculate the amount of steel required for a slab, you need to consider factors such as the type of slab, its thickness, and the structural requirements. The formula to estimate the quantity of steel reinforcement is:
Weight of steel = Volume of slab (m3) × 80 kg to 90 kg per cubic meter volume of concrete.
- Convert thickness in feet
- Calculate wet volume of concrete = square footage × thickness in feet
- Convert cubic feet into cubic metres
- Taking steel quantity 80 kg to 90 kg per cubic meter volume of concrete. On average, we take 85kg/m3.
Assuming it a normal residential building with light loading conditions, thickness of slab will be 4 inch thick. For example, for the plan area of 700 sq ft, total volume of concrete required = (700 ×0.33) ÷ 35.3147 = 6.54 m3, as per thumb rule 80 kg to 90 kg of steel are required per cubic meter volume of concrete, so as 80 kg × 6.54 = 523 kg or 90 kg × 6.54 = 588 kg.
How much steel required for 700 sq ft slab 4″ thickness?
Steel required for 700 sq ft RCC roof slab at 4 inch thickness. Multiply area and thickness to calculate wet volume of concrete. Volume of 700 sq ft of RCC slab at 4 inches thick in m3 = (700 × 4/12) ÷ 35.32 = 6.6 m3.
At 4″ thickness, the total quantity of steel required for 700 sq ft (6.6 cubic meters) RCC roof slab is equal to = 85 × 6.6 = 561 kg. This means, 562 kg of steel is required per 700 sq ft of 4-inch thick RCC roof slab.
How much steel required for 700 sq ft slab 5″ thickness?
Steel required for 700 sq ft RCC roof slab at 5 inch thickness. Multiply area and thickness to calculate wet volume of concrete. Volume of 700 sq ft of RCC slab at 5 inches thick in m3 = (700 × 5/12) ÷ 35.32 = 8.25 m3.
At 5″ thickness, the total quantity of steel required for 700 sq ft (8.25 cubic meters) RCC roof slab is equal to = 85 × 8.25 = 701 kg. This means, 702 kg of steel is required per 700 sq ft of 5-inch thick RCC roof slab.
How much steel required for 700 sq ft slab 6″ thickness?
Steel required for 700 sq ft RCC roof slab at 6 inch thickness. Multiply area and thickness to calculate wet volume of concrete. Volume of 700 sq ft of RCC slab at 6 inches thick in m3 = (700 × 6/12) ÷ 35.32 = 9.9 m3.
At 6″ thickness, the total quantity of steel required for 700 sq ft (9.9 cubic meters) RCC roof slab is equal to = 85 × 9.9 = 842 kg. This means, 842 kg of steel is required per 700 sq ft of 6-inch thick RCC roof slab.
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Conclusions:
On average, 562 kg of steel quantity are required for 600 sq ft and 4 inch thick RCC roof slab. For the same area, 702 kg of steel with a thickness 5 inches and 842 kg of steel with a thickness of 6 inches are required.