Thumb Rulers For Civil Engineers

In the early stages of a project, we are often asked how large structural elements will be before we have had a chance to perform the necessary computations. Thumb rules help you in finding out the solution using a simple mathematical formula and make smart decisions whenever needed. But, while using these thumb rules, you must remember that the thumb rule never gives the exact or accurate results, you just have used them for approximate results.

1- Thumb rule for estimating the Concrete Volume with respect to the area

The volume of concrete required = 0.038 m3/square feet area

Example

If Plan Area = 40 x 20 = 800 Sq. m.

So, for the plan area of 800 Sq. m. area the total volume of concrete required

= 800 x 0.038m3 = 30.4m3

2- Thumb rule for Steel quantity required for Slab, Beams, Footings  and Columns

Steel required in residential buildings = 4.5 Kgs – 4.75 Kgs / Sq. Ft.

Steel required For Commercial buildings = 5.0 Kgs-5.50 Kgs/Sq. Ft.

you can also use BN Datta recommendations for the more accurate result

The following recommendations Thumb Rules For Civil Engineers are given in B N Datta for the Steel quantity used in different members of the building

Percentage of Steel in Structural Members

1- Slab – 1% of the total volume of concrete

2- Beam – 2% of the total volume of concrete

3- Column – 2.5% of total volume of concrete

4- Footings – 0.8% of the total volume of concrete

Example

How to calculate the steel quantity of slab having the Length, width, and depth of the slab is 5m x 4m x 0.15m

Step 1: Calculate the Volume of Concrete

The Total Volume of Concrete for given Slab = 5 x 4 x 0.15

= 3m3

Step 2: Calculate the steel quantity using formula

As per the guidelines are given in B N Datta reference book the steel quantity of slab is 1% of the total volume of concrete utilized.

Thumb rule to estimate Steel quantity of above slab = Volume of Concrete x Density of Steel x % of Steel of Member

Steel weight required for above slab = 3 x 7850 x 0.01 = 235Kgs

For accurate estimation, you can refer to Bar Bending Schedule

3- Thumb Rules For Civil Engineers to estimate the Shuttering area

Shuttering costs is taken as 15-18% of the total construction of the building.Shuttering work is done to bring the concrete in Shape. Thumb rule to estimate the shuttering required is 6 times the quantity of concrete or 2.4 times of Plinth area.

For example

the concrete quantity is 0.5m3, then

Area of Shuttering is 0.5 x 6 = 3m2

Components of Shuttering

The Shuttering plate Ply, Battens, Nails are components of Shuttering.

Shuttering Ply Quantity estimation

Suppose, The shuttering Ply has a length, width & depth of 2.44 x 1.22 x 0.012

The No. of Shuttering Ply sheets = 0.22 times of Shuttering

Suppose, the shuttering area = 3m

Then Ply required for shuttering = 0.22 x 3 = 0.66m2

Battens Quantity Calculation

Shuttering batten usually have a length & width of 75mm x 40mm.

Batten Quantity = 19.82 x No. of Ply Sheets

If work requires 25 Ply sheets, the total quantity of Battens are 19.82 x 25 = 495 Battens

Nails & Binding Wire Quantity in Shuttering:

Approximately, 75 gams of Nails used in shuttering of 1m2 area.

75gms of Binding wire is used for every 1 m2 of Shuttering.

Thumb rule for Shuttering oil estimation 

Shuttering oil is apply on shuttering plate surface used to de-frame or de-assemble from the concrete easily.

Total required Shuttering oil  = 0.065 x Total Area of Shuttering

(or)

For every 15m2 of shuttering 1 liter of shuttering oil is consumed.

Example

If, total area of shuttering is 15 m2, then Shuttering oil Consumption = 0.065 x 15 = 0.975.

4- Thumb rule used for Cement, Sand, Coarse Aggregate Quantity in Different grades of Concrete 

Note: 1 bag of cement = 50 Kgs

Thumb rule for Cement required in Brickwork, Cement Masonry & Plastering work in construction:

Thumb Rules For Civil Engineers for Brickwork

Thumb Rules For Civil Engineers for Cement Masonry Quantity

Thumb Rules Plastering Quantity