Thumb rules are used for quick decision making and are approximate estimates. Thumb rule can never be perfect or accurate.
Site engineer and supervisor are greatly benefited by thumb rules to arrive at quick decision.
Every civil engineer or site supervisor shall have basic knowledge about certain civil engineering basics. The below-mentioned are must-have knowledge about civil engineering and practical knowledge. We will cover in-depth knowledge about civil engineering field and practice.
This post will contain civil engineering tips and tricks That will be of immense importance to civil engineers.
We have shared an extensive list of thumb rules used in construction for various activities. If you get to benefit from it then please share.
Thumb Rules In Building Construction Cost
Thumb rule for construction cost estimates can speed up the rough estimation process. Based on thumb rules in civil engineering, one can have approximate cost and material and labour requirement as well.
Basic thumb rule for Building material requirements and building work per unit area is given below:
|Sr. No.||Material/ Work||Thumb Rule|
|2.||Steel||3 to 5 Kg/sqft|
|5.||Structural Civil Work||₹ 751.25/sqft|
|6.||Finishing Works||₹ 470/sqft|
|7.||Electrical Cost||₹ 133/sqft|
|8.||Plumbing Cost||₹ 126/sqft|
|9.||Fire Fighting Cost||₹ 40/sqft|
|10.||External Development Cost||₹ 94.5/sqft|
Thumb rule for construction cost of building material percentage wise
|Description||Thumb rule (% of Total Cost)|
Thumb rules for construction cost
The average cost of Construction based on the quality of construction is shown below.
|Sr. No.||Construction based on Quality||Thumb Rule|
|1.||Basic Quality Construction||1100 Rs./Sqft|
|2.||Medium Quality Construction||1400 Rs./Sqft|
|3.||High Quality Construction||1800 Rs./Sqft|
Thumb rule for average cost of construction for 1000 sqft house.
|Sr. No.||Description of Work||Average Cost for 1000 sqft home|
|1.||Cost of Architect||Rs. 15,000 Onwards|
|2.||Brick wall without RCC||Rs. 800 per sqft|
|3.||Brick wall With RCC||Rs. 900 per sqft|
|4.||Civil Work||Rs. 1500 per sqft|
|5.||Electric and Plumbing||Rs. 2500 per sqft|
|6.||Raw Material Cost||Rs. 7 Lakh Onwards|
Thumb rule for building cost based on whole project cost in terms of percentage.
|1.||Excavation and Filling Earthwork||0.5%|
|3.||Damp Proof Course||1%|
|7.||Doors and window||16%|
Cost of building general thumb rules
|Sr. No.||Work||Thumb Rule|
|Cost of Material and Labour|
|1.||Material Cost||70% of Building Cost|
|2.||Labour Cost||30% of Building Cost|
|Direct and Overhead Cost|
|1.||Direct Cost||85% building cost|
|2.||Overhead expense||15% of Building Cost|
|Foundation and Superstructure|
|1.||Cost of Foundation||15% of Building Cost|
|2.||Cost of Superstructure||85% of Building Cost|
|Electrical and Sanitary Work|
|1.||Plumbing and sanitation cost||8% of Building Cost|
|2.||Cost of Electrical Work||8% of Building Cost|
Thumb Rule For Slab
- The minimum thickness of slab is 125mm.
- The minimum diameter of bars used in slab is 8mm.
- Fe 500 Steel should be used in the slab.
- Clear cover of 15mm to 20mm should be provided in slab.
- Maximum diameter of bars used in slab is 1/8th times of slab thickness.
- Steel required in slab is 1% of the total volume of concrete.
- M15 Grade of concrete or above it should be used in slab.
- Spacing between reinforcement in slab should not be less than 150mm c/c.
Thumb Rule For Beam
- Steel required in beam is 2% of total volume of concrete.
- Minimum clear cover of 40mm shall be provided in beams.
- M20 grade of concrete should be used in beam construction.
- Minimum 4 bars shall be provided in beams. 2 bars of 12mm at top and 2 bars of 10mm at bottom.
- M15 Grade of concrete or above it should be used in slab.
- Spacing between reinforcement in slab should not be less then 150mm c/c.
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Thumb Rule For Column
- Steel required in Column is 2.5% of total volume of concrete.
- Minimum steel requirement in column = 0.8% of gross area of concrete
Maximum steel requirement in column = 6% of the gross area of concrete
- Spacing between Longitudinal reinforcement should not be more than 300mm.
- Minimum clear cover in column is 40mm. 25mm clear cover is provided if column is less than 200mm.
- Minimum dia of 12mm bars 4 numbers should be used in column.
- The maximum diameter of reinforcing bars in column should be not more than 50mm.
- Overlapping distance in longitudinal bars should not be less than 24 times the smallest bar dia.
- Maximum spacing of stirrups is 16D or B or 300mm whichever is less.
- Minimum size of column should not less then 9″ X 9″.
- For G+1 Structure 9″ X 12″ (225mm X 300mm) Column should be used.
- Maximum space between two column of size 9″ X 9″ should not be more than 4 meter.
- M20 Grade of concrete should be used in concreting column.
- Fe 500 Steel is also recommended for column reinforcement.
- Column should be equally spaced in a grid so as to efficiently transfer the load.
Thumb Rule for Foundation
- Steel required in footing is 0.8% of total volume of concrete
- The clear cover of main reinforcement in footing is 50mm.
- A minimum 10mm bar shall be used for foundation footing.
- M20 grade of concrete or above should be used for foundation.
- Length, width and depth of foundation should not be less than 1 meter.
- Footing thickness should not be less then 40 cm.
- Pile foundation should be used if soil bearing capacity is less than 24 kN/m3.
Thumb Rule For Labour Productivity
Manpower productivity estimates are useful for calculating number of labour or man required to perform a task.
Labour output per day in construction activity can help to estimate the number of labour required to perform a particular work or task.
Manpower productivity estimates are shown below:
|Sr. No.||Activity||Manpower||Output (8Hrs)|
|1.||Brickwork||Mason – 1|
Male Mazdoor – 0.75
Female Mazdoor – 0.5
|2.||Wall Plastering||Mason – 1|
Male Mazdoor – 1
Female Mazdoor – 0.5
|3.||Ceiling Plastering||Mason – 1|
Male Mazdoor – 0.75
Female Mazdoor – 0.5
|4.||Shuttering Work||Carpenter – 2.25|
Foremen – 0.2
Helper – 2.25
|5.||Steel Work||Bar Bender – 1|
Helper – 1
|6.||Tiling Work||Tile Mason – 1|
Helper – 1
|7.||Block Work||Mason – 2|
Male Mazdoor – 1.75
Female Mazdoor – 1.75
|8.||Earth Work||Male Coolie – 5|
Female Coolie – 4
|9.||Painting Work||Painter Skilled – 1||600 sqft|
|10.||Carpenter||Carpenter skilled – 1|
Helper – 1
|11.||Steel Binding||Fitter – 1|
Helper – 1
From the above standard labour productivity in construction, we can calculate labour requirement and estimation.
Suppose for shuttering work, we need to know shuttering carpenter productivity per day. From the above thumb rule of labor,
For doing 11 m2 of work, Shuttering carpenter productivity per day is,
- Carpenter – 2.25
- Foremen – 0.2
- Helper – 2.25
Thumb Rule For Reinforcement
Calculation of steel is important as it is one of the costliest building material.
- Lapping is not allowed for the bars more then 36mm dia.
- Longitudinal reinforcement in structural members shall not be less then 0.8% and not more the 6% gross cross-sectional area.
- Atleast 4 bars should be used in square column and 6 bars in circular column section.
Important thumb rule for calculating steel based on building type and for structural members like slab, beam, column and footing is very useful.
Thumb rule for steel in building construction is shown below:
|Sr. No.||Type of Building||Thumb rule for Steel (Kg/Sqft)|
|1.||Residential Building||4.5 – 4.75|
|2.||Commercial Building||5 – 5.5|
|3.||Heavy Structure or Tall Mass projects||6 – 8|
The above thumb rule for steel in RCC estimation is not so accurate. For more approximate quantity of steel requirement refer B N Datta as shown below. Steel percentage in concrete as per IS code for different members is shown below:
|Sr. No.||Member of Building||Percentage of Steel|
|1.||Slab||1% of Total Volume of Concrete|
|2.||Beam||2% of Total Volume of Concrete|
|3.||Column||2.5% of Total Volume of Concrete|
|4.||Footing||0.8% of Total Volume of Concrete|
Example for steel requirement
Calculate steel requirement of slab of dimension 3m X 5m X 0.15m
Total volume of concrete = 3 x 5 x 0.15 = 2.25 m3
Steel required = 2.25 X 1% …(1% taken from table for slab)
For weight of steel multiply by density of steel that is 7850kg/m3. As 1 cubic meter of steel weight 7850 Kg.
Weight of steel required = 0.0225 X 7850 = 176.625 Kg
The weight of steel calculated from the above method is approximate, for accurate quantity use bar bending schedule.
Weight of Steel Bars Per meter length
For calculating weight of steel or reinforcement per unit length following thumbrules can be used.
Weight of steel = D2/162
For length L, Weight of r/f = (D2/162) X L
Weight of steel bars per unit length for different diameter of bars are shown below:
|Sr. No.||Diameter of Bars||Weight of steel bar per meter|
|1.||6mm bar||0.222 kg|
|2.||8mm bar||0.395 kg|
|3.||10mm bar||0.616 kg|
|4.||12mm bar||0.888 kg|
|5.||16mm bar||1.578 kg|
|6.||20mm bar||2.466 kg|
|7.||25mm bar||3.853 kg|
|8.||32mm bar||6.313 kg|
|9.||40mm bar||9.865 kg|
Thumb rule for steel quantity is shown below:
- Thumb rule for steel in kg/m3 for 6mm dia bar is 0.222 Kg.
Thumb Rule For Concrete
Concrete volume can be easily calculated if you know the plan area.
Thumb rule for calculating concrete volume = 0.038 m3 per square foot of plan area.
Thus if floor plan of a house is 30 X 20,
then total plan area= 600 sqft
volume of concrete = 600 X 0.038 m3 = 22.8 m3
Thus total volume of concrete to build 600 sqft house is 22.8 m3.
Concreting work can be done easily at site if proportion of cement, sand and aggregate are known. Based on the mix design of concrete, ratio of cement, sand and aggregate changes, which can be seen in the table given below.
|Sr. No.||Concrete Mix||Ratio||Cement Qty (Bags)||Coarse Aggregate (m3)||Fine Aggregate (m3)|
Thumb Rule For Concrete Mix Design
- In 1 cu.mt of freshly mixed concrete, if 4 liter of water is added then,
- Slump value will increased by 25mm
- Compressive strength of concrete will decrease by 1.5 N/mm2 to 2 N/mm2
- Shrinkage potential will be increased by 10%
- 25% of cement bag will be wasted
- If temperature of freshly mixed concrete is increased by 1% then,
- Slump will be equal to addition of 4 liter of water
- Air content will be decreased by 1%
- Compressive strength of concrete will decrease by 1 N/mm2 to 1.5 N/mm2
- If air content of freshly mixed concrete is,
- Increased by 1%, then compressive strength will be decreased by 5%
- Decreased by 1%, then yield of concrete will be decreased by 0.03 m3 per 1 m3.
- Decreased by 1%, then slump of concrete will be decreased by 12.5mm.
- Decreased by 1%, then durability of concrete will be decreased by 10%.
Thumb Rule for Concrete Work
- Volume of concrete required is 0.038 m3/sqft area.
- Standard weight of 1 bag of cement is 50 kg.
- 1 bag of cement is equal to 1.25 cuft or 0.0347 m3.
- In high rise building 0.5 bags of cement is required per square feet of area.
- Density of cement is 1440 kg/m3.
- Specific gravity of cement is 3.15
- Average cost of concrete is 50 to 80$ per cubic meter.
- Initial setting time of cement is 30 minutes and final setting time of cement is 10 hrs.
Thumb Rule for Shuttering Work
Shuttering is required for pouring concrete so that it take appropriate shape. Shuttering is important part of building construction.
Cost of shuttering is almost 15% to 18% of the total cost of building. Thus if shuttering quantity is not taken appropriately then it can lead to drain of money.
Thumb rule for shuttering is shown below
- Shuttering is 6 time the concrete quantity or,
- Shuttering is 2.4 times the plinth area
If we need to concrete 5 cubic meter then the shuttering required can be found with thumb rule by multiplying concrete quantity by 6.
Shuttering area = 5 X 6 = 30 m2
Different shuttering members are Ply, Battens, Nails.
Shuttering Ply dimension are 2.44 m X 1.22 m X 0.012 m
Number of shuttering ply sheets needed for shuttering = 0.22 X Shuttering Area
Let’s assume we need to concrete 100m area. Then Shuttering needed for concreting is 0.22 time 100.
Ply required for shuttering = 0.22 X 100 = 22 numbers
Battens For Shuttering
General dimension of battens are 75mm X 40mm
Thumb rule for Batten Quantity = 19.82 X Number of Ply
For 22 number of ply, the quantity of battens is = 19.82 X 22 = 436 Battens
Nails and Binding Wire
- Thumb rule for nails required in shuttering is 75 grams per 1 m2 of shuttering.
- Thumb rule for binding wire is 75 grams per 1 m2 of shuttering area.
Oil is applied on shuttering surface for easy removal of shuttering. Quantity of oil needed for shuttering is
- 0.065 times total shuttering area
- For 15 m2 of shuttering, 1 liter of oil is needed
For 100m2 of shuttering oil needed for shuttering = 0.065 X 100 = 6.5 liter
|Sr. No.||Member||Thumb Rule|
|1.||Shuttering Area||6 times the concrete area|
2.4 times the plinth area
|2.||Shuttering Ply||0.22 times Shuttering Area|
|3.||Battens||19.82 times Shuttering Ply|
|4.||Nails||75 grams per 1 m2 of shuttering area|
|5.||Binding Wire||75 grams per 1 m2 of shuttering area|
|6.||Shuttering Oil||0.065 times total shuttering area|
For 15 m2 of shuttering, 1 liter of oil is needed
Thumb rule for removing Shuttering
Shuttering should be remoced only after the member has attained suitable strength. Below table mentions detail about removal of shuttering duration.
|Sr. No.||Member of Structure||Days|
|1.||Sides of foundation, column, beams and walls||2 days|
|2.||Sides of span larger then 4.5 meter||14 days|
|3.||Sides of span shorter then 4.5 meter||7 days|
|4.||Sides of beams and arches upto 6 meter span||14 days|
|5.||Sides of beams and arches from 6 m to 9 m span||21 days|
|6.||Sides of beams and arches above 9 meter span||28 days|
Thumb Rule For Brickwork
Number of Bricks required in 1 cubic meter = 500 number
Suppose for 20m3 of brickwork is needed to be done
Then the quantity of brickwork required for 20m3 of brickwork = 20 X 500 = 10000 bricks.
Thus 10000 number of bricks is required for brickwork of 20m3.
Quantity of cement required in 1 m3 of brickwork for different size of brickwork varies. Below is a thumbrule for brickwork cement required.
|Sr. No.||Brickwork size||Cement required (m3)||Cement Quantity (Bags)|
|1.||230mm Brickwork||0.876 m3||25.4|
|2.||115 mm Brickwork||0.218 m3||6.32|
Thumb Rule for Brickwork for different mix ratio thickness of brickwork along with cement sand required are given below.
|Sr. No.||Brickwork||Mix Ratio||Mortar Thick (mm)||Cement Qty (Bags/m3)||Sand (m3)|
|1.||100 mm thick||1:4||10||0.15||0.035|
|2.||200 mm thick||1:6||10||1.4||0.30|
|3.||200 mm thick||1:5||10||1.7||0.25|
Thumb rules of bricks
- Standard size of bricks is 19cm X 9cm X 4cm.
- Weight of first-class clay bricks should be 3.85 kg.
- Crushing strength of bricks is 10.5 MN/m2.
- Water absorption in bricks is 12% to 15%.
- Compressive strength of bricks is 36 KN/cm2.
- Number of bricks in 1m3 of brick masonry is 550 bricks.
Thumb Rule For Plastering
Based on experience and practice following thumb rule for plastering is used in construction and building work.
Cement required changes according to type of plastering. Cement required for internal plastering is comparatively lower then cement required for external plastering.
Below is a table containing cement requirement for different type of plastering work.
|Sr. No.||Plastering Type||Cement Qty (Bags/m2)||Cement Qty (Kg/m2)|
Cement sand requirement for wall and ceiling plastering are shown below:
|Sr. No.||Plastering Type||Ratio||Plaster Thickness (mm)||Cement (Bags/m2)||Sand (m3/m2)|
|1.||Internal wall Plaster||1:3||15||0.16||0.017|
|2.||External Wall Plaster||1:4||20||0.17||0.024|
Thumb Rule For Cement Masonry Work
Cement requirement in masonry work varies according to cement masonry type and mix. Quantity of cement required for different cement masonary work and mix is shown below.
|Sr. No.||Masonry Type and Mix||Cement Qty (Bags/m2)||Cement Qty (Kg/m2)|
|1.||200mm Masonry Work (1:6)||0.124||6.20|
|2.||150mm Masonry Work (1:6)||0.093||4.65|
|3.||200mm Masonry Work (1:4)||0.206||10.30|
|4.||150mm Masonry Work (1:4)||0.144||7.20|
|5.||100mm Masonry Work (1:4)||0.103||5.15|
Thumb Rule for Flooring
Quantity of cement required for laying of flooring can be calculated based on the thumb rule given below.
|Sr. No.||Type of Flooring||Thumb Rule for cement|
|1.||Marble Flooring||0.3 Bags/m2|
|2.||Marble Skirting||0.025 Bags/m|
|3.||Marble Glading||0.27 Bags/m2|
|4.||Terrace Flooring||0.3 Bags/m2|
|5.||Granolithic Flooring||0.25 Bags/m2|
|6.||Mangalore Tile||0.35 Bags/m2|
|7.||Ceramic Flooring||0.3 Bags/m2|
|8.||Vitrified Tile Flooring||0.28 Bags/m2|
|9.||Vitrified and ceramic tile dado||0.25 Bags/m2|
|10.||Anti skid Flooring||0.28 Bags/m2|
Thumb Rule for Water Proofing
|Sr. No.||Water Proofing work||Thumb rule|
|1.||Water proofing for sunk slab||0.25 Bags/m2|
|2.||Water proofing for walls||0.25 Bags/m2|
|3.||Water proofing for toilets||0.63 Bags/m2|
Thumb Rule for Cement
Bulk Density of Cement
Density of cement according to type are shown below:
|Sr. No.||Cement Types||Density (kg/m3)||Density (KN/m3)|
|3.||Plain Cement Concrete||2400||24|
Below is a list of cement types and initial and final setting time of respective cement.
|Sr. No.||Type of Cement||Initial Setting Time||Final Setting Time|
|1.||Ordinary Portland Cement (33 Grade)||30 minute||600 minute|
|2.||Ordinary Portland Cement (43 Grade)||30 minute||600 minute|
|3.||Ordinary Portland Cement (53 Grade)||30 minute||600 minute|
|4.||Sulphate Resistant Cement||30 minute||600 minute|
|5.||Portland Pozzolona Cement||30 minute||600 minute|
|6.||Rapid Hardening Cement||30 minute||600 minute|
|7.||Slag Cement||30 minute||600 minute|
|8.||High Alumina Cement||30 minute||600 minute|
|9.||Super Sulphated Cement||30 minute||600 minute|
|10.||Low Heat Cement||60 minute||600 minute|
|11.||Masonry Cement||90 minute||600 minute|
|12.||IRS T-40||60 minute||600 minute|
Thumb rule for Achieving Economy
In order to save money in building construction, one has to follow certain guidelines and thumb rule. Following these thumb rules for building construction will result in saving money and economic building.
- Use formwork as many time as possible to achieve economy.
- Minimum floor to floor height will result in saving of money.
- Column layout should be placed in a uniform grid.
- Standard column size should be used.
- Same depth of beam should be used, if possible.
- Local available material should be used to minimise cost.
- High strength concrete should be used.
- To remove formwork earlier high early strength concrete should be used.
- To minimise honey combing and air pockets in concrete self consolidating concrete should be used.
- Avoid congestion of steel especially at beam column joints.
- Use large size bars in column and smaller size bars in slab.
Frequently Asked Questions
Some of the most frequently asked question in civil engineering are shown below.
How many kg of steel is required in 1m3 of concrete
7850 kg of steel is required in 1m3 of concrete
What percentage of steel in slab as per is 456
Minimum percentage of steel in slab is 0.8% and maximum percentage of steel in slab is 4%.