# 50 Important Thumb Rules in Civil Engineering

50 Important Thumb Rules For Civil Engineers

Thumb Rules for construction is an experienced base data, not collected from any books So, please don’t consider it accurate but it is an approximate figure.

Thumb Rule For Excavation

### 1.) Excavation Quantity – 3 x Concrete Quantity of footing

Let’s take an example, Footing Size – 2 x 1mtr.

Depth of Footing – 3mtr.

So, Concrete Quantity of footing = 2x1x3 = 6m3.

Then, Excavation Quantity – 3 x concrete quantity

– 3 x 6 = 18m3.

Prove that:-

Always Consider Offsets for excavations

Length of Footing  – 0.5 + 2 + 0.5 = 3mtr.

Width of Footing  – 0.5 + 1 + 0.5 = 2mtr.

Depth of Footing – 0.100 + 3 = 3.1mtr.

### Then, Excavation Quantity – L x B x H

– 3 x 2 x 3.1 = 18.6m3.

### 2.)  Thumb Rule for Concrete Volume of Area

Concrete consume in 1sqft Area = 0.038m3 of concrete required

Let’s take an example,

Let, Area of Plot – 40’x20’ = 800sqft. Then, the Volume of concrete – 800×0.038

So, the Volume of concrete – 30.4m3 (for any structural members area).

### 3.)  Steel Quantity Required for Slab, beam, footing & columns. For residential buildings – 4.5 to 4.75kg/-Sqft.

For commercial buildings – 5 to 5.50kg/-Sqft Or 80 to 150kg/m3.

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B.N Dutta recommendation

i). Slab – 1% of total concrete Volume.

ii). Beam – 2% of total concrete Volume.

iii). Column – 2.5% of total concrete Volume.

iv). Footing – 0.8% of total concrete Volume.

For Example,

Slab having dimension – 5mx4mx0.15m (L x B x D) Total  Concrete volume – 3m3

According to B.N Dutta’s recommendation, Slab – 1% of total concrete Volume.

So, Required Qty of Steel in Slab = Concrete Volume x Density of steel x 1%

= 3m3 x 7850 kg/m3 x 0.01 = 235kg.

### 4.)  Shuttering Area Calculation by Thumb rule

Shuttering Cost – 15 to 18% of total construction cost.

Suppose, Total Structure Cost – Rs.2Lakh.

So, Total Shuttering Cost – 15 to 18% of 2lakh = Rs.30,000 to 36,000/-

Shuttering Required – 6 times more than concrete quantity or 2.4 times of Plinth Area.

### 5.)  Shuttering Ply quantity Calculation by Thumb rule

Suppose, Ply size – 2.44 x 1.22 x 0.012mm.

No. of Ply Sheets required = 0.22 times of shuttering area

Let, Area of Shuttering = 5m2.

So, Shuttering Ply Required = 0.22 x 5 = 1.1m2.

### 6.)  Batten quantity Calculation by Thumb rule

Batten Quantity – 19.82 x No. of Ply Boards.

Let, Construction required 25 Ply sheets

So, Quantity of Batten required = 19.82 x 25 = 495 Nos. Battens.

### 7.)  Nails quantity Calculation by Thumb rule

In 1m2 Shuttering = 75gm nails are required.

In 1m2 Shuttering = 75gm bolts are required.

### 8.)  Binding wire quantity Calculation by Thumb rule

In 1m2 Shuttering = 75gm binding wire is required.

### 9.)  Shuttering oil quantity Calculation by Thumb rule

Oil Required – 0.065 x total area of shuttering.

Let’s take an example,

Suppose, Shuttering Area = 15m2

So, Oil Required = 15 x 0.065 = 0.975 or 1ltr.

10.) Thumb rule for the quantity of cement/sand/Coarse aggregates and fine aggregates in different grades for 1 m3.

 Concrete Mix Cement Coarse Aggregates Sand M – 5 2.82 bags 0.98m3 0.49m3 M – 7.5 3.48 bags 0.97m3 0.48m3 M – 10 4.50 bags 0.90m3 0.45m3 M – 15 6.60 bags 0.88m3 0.44m3 M – 20 8.40 bags 0.84m3 0.42m3

11.) Thumb rule for the quantity of  Plaster

 Types of Plastering Cement Bags Cement in Kg Rough Plastering 0.09bags/m2 4.5kg/m2 Internal Plastering 0.09bags/m2 4.5kg/m2 Duct Plastering 0.09bags/m2 4.5kg/m2 External Plastering 0.175bags/m2 8.75kg/m2 Stucco  Plastering 0.175bags/m2 8.75kg/m2 Lathen Plasterin 0.55bags/m2 27.5kg/m2

12.)  Thumb rule for Brick Masonry Work

 Brickwork for 1m3 Cement Qty in m3 Cement Qty. in bags 230mm width (9’’) 0.867m3 25.4 bags 115mm width (5’’) 0.218m3 6.32 bags

13.) Thumb rule for Masonry wall Mortar Quantity

A 100sqft wall consume

Cement bags – 2Nos.

Sand – 24Nos. Bucket. (1:4)

And, 1 bag cement containing – 3 bucket

So, Cement Bucket – 6 Nos.

Sand Bucket – 24 Nos.

14.) Thumb rule for Masonry wall Bricks Quantity

A 100sqft wall consume

Brick 9’’ – 950 -1000 bricks.

Brick 4’’ – 450 – 500 bricks.

But Always order 50 to 100 bricks extra for wastage.

### 15.)  Cement bags quantity in Concrete Slab

Let’s Take an Example

Slab Area – 900Sqft

So, Cement Bags – 9 x 7 = 63 Bags.

Let’s take another example

Slab Area – 1300sqft

So, Cement Bags – 13 x 7 = 91 Bags.

16.) Find the depth of Foundation by thumb rule

As per IS Code – 1080 – 1982

Depth of foundation for a multistory building.

5% to 10% of the height of the building.

For example,

No. of the floor – 17Nos & overhead tank height 3mtr.

Ground to first-floor height = 4.2mtr.

1st to 17th floor – 3mtr.

So, Total Height of Building – 4.2 + (17 x 3) + 3 = 58.21mtr.

So, the depth of foundation may be as per thumb rules.

Total building height x 5 to 10%

= 58.21 x 5% = 2.91mtr or, 58.21 x 10% = 5.82mtr.

It depends on soil condition. ### 17.) Labor Productivity by thumb rule

Brickwork – 1 mason + 1 Labor = 1.25m3 or 45cft ( for 8 hrs).

Wall Plastering – 1 mason + 1 Labor = 10m2 or 107sft ( for 8 hrs).

Ceiling Plastering – 1 mason + 1 Labor = 8m2 or 85sft ( for 8 hrs).

External Plastering – 1 mason + 1 Labor = 8m2 or 85sft ( for 8 hrs).

Carpenter – 1 skilled + 1 unskilled = 4m2 ( for 8 hrs).

Bar Binder – 1 skilled + 1 unskilled = 150kg ( for 8 hrs).

Tile Work – 1 mason + 1 Labor = 10sqm ( for 8 hrs).

Earth digging – 5 male labor + 4 female Labor = 1000cft ( for 8 hrs).

18). Bricks Required in 1m3

500 Nos. (For standard sizes bricks).

19). Mortar Required for 500 Bricks

0.25m3.

## 20). Concrete Qty = Area x  thumb rules

Area – Total Built-up Area ( Plinth area x No. of Floors).

For Commercial –  Area x 0.5m3

For Residential – Area x 0.2m3

## 21). House Construction Cost by Thumb rules

Civil Structural works cost – Rs.1150/-sqft.

Finishing work cost – Rs. 650/-sqft.

22). Painting cost by thumb rules

2 layer putty + 2 Layer paint coat.

Rs. 18 to 20/-sqft.

23).  Flooring

Marble Rate – Rs.100 to 120/-sqft.

Granite Rate – Rs.20 to 22/-sqft.

24).  Electricals

Rs.70to120/-sqft For materials (A rough guide).

Rs.15 to 32/-sqft for labor.

25).  Cement Required per m3

M10  – 210kg

M20 320kg

M25 – 340kg

M30 – 380kg

M35 – 410kg

M40 – 430kg

M45 – 450kg

### 26).  Anti – termite treatment

Chemicals name is chlorophyrifac 20%.

Diluting 5ltr of chemical with 95ltr of water and usage is 7.5sqm per ltr.

To provide 1’’ dia. Hole and 1-foot depth Use 7.5sqm per ltr.

27).  Water – Proofing for walls

0.23bags /sqm.

28).  Water – Proofing for Balcony/toilet

0.65bags /sqm.

### 29).  Water – Proofing for Sunken Slab

0.23bags /sqm.

30).  Vitrified tile flooring

0.28 cement bags/sqm.

31).  Ceramic tile flooring

0.28 cement bags/sqm.

0.27 cement bags/sqm.

33).   AAC Blocks 12.5Nos/sqm.

34).  Wall Putty

14 to 15sqft/-kg (For 2 Coats).

– 8 to 12sqft/-kg (For 3 Coat).

35).  Primer

– 120 to 140sqft/-kg (For 1 Coat).

– 70 to 90sqft/-kg (For 2 Coat).

36). Labor cost for painting

Rs.10 to 15/-sqft.

### 37).  Cement  Consume for Plastering by thumb Rules

For External Plastering – 8.75kg/m2.

For Internal Plastering – 4.5kg/m2.

Ceiling Plastering – 0.11bags/m2.

### 38). Labor required for Demolishing by thumb Rules

PCC (1:2:4 or 1:3:6) for 1m3 – 2 Labors (8hrs).

RCC (Lead 50mtr) for 1 m3 – 4 Labors (8hrs).

Brickwork (Lead 50mtr) for 1 m3 – 2Labor (8hrs).

Removing Mortars for 10m3 – 4 mason & 25 labors with (cleaning & stacking).

Labor required for Masonry by thumb Rules

39). Brickwork :- 7.55sqm – 1 mason + 1 man labor + 1 Women labor (for 8hrs).

40). Block work :- 12m2    – 1 mason + 1 man labor + 1 Women labor (for 8hrs).

41). DPC :- 100m2 – 5 mason + 6 man labor (for 8hrs).

42). Cement Consume for Marble flooring – 0.3bags/sqm.

### 43). Thumb Rules For Contractor

i). Floor to floor height should be minimum.

ii). Use repetitive formwork & Ms shuttering.

iii). Use Standard size of Columns.

iv). Same beam bottom & beam depth.

v). Use high-strength concrete in column eg.M30.

vi). Use high early strength concrete.

Vii). Use locally available materials.

## 44). Thumb Rules to calculate materials qty. for house construction.

Let, Built-up Area – 1000sqft

i). Cement – Built-up Area x 0.4

= 1000 x 0.4 = 400bags

ii). Sand – Built-up Area x 0.816

= 1000 x 0.816 = 816 tone or 51m3.

iii). Aggregates – Built-up Area x 0.608

= 1000 x 0.608 = 608 tone.

iv). Steel – Built-up Area x 4

= 1000 x 4 = 4tone.

v). Paint – Built-up Area x 0.18

= 1000 x 0.18 = 18ltr.

vi). Flooring – Built-up Area x 1.3

= 1000 x 1.3 = 1300sqft (with skirting).

vii). Bricks – Built-up Area x 8

= 1000 x 8 = 8000Nos.

### 45). Thumb Rules to Find Depth of Beams

According to ACI Code – 318 -14 (Table no. 9.5A)

Depth of beam in inch = Length of a beam in feet

For Example,

Length of beam = 5mtr. Or 5 x 3.28 = 16.40 feet

So, depth of beam = 16.40 inches.

### 46). Thumb Rules for Design beam size

Depth of beam = Effective Span / 12

For Example,

Length of Span = 5mtr or 5000 / 12 = 417mm

or, depth of beam = 16.40 inches.

## 47). Thumb Rules for Design Slab size

As per IS 456,

i). Simply supported Slab – Span/30

ii). Continuous Slab – Span/30

iii). Cantilever Slab – Span/7

This is applicable for slab span 10mtr or less than 10mtr only not for more than 10mtr.

### 48). Standard data for tolerance

i). Accuracy of measuring equipment in batching plant

i). cement – +_2%

ii). Aggregates –  +_3%

iv). Water –  +_3%

v). Mixing time – 2 minutes for 1 mixing.

49). Standard data for tolerance

ii). Tolerance on steel diameter in length

i). 0 – 25mm – +_0.5%

ii). 25 – 35mm – +_0.6%

iii). 35 – 50mm – +_0.8%

49). Standard data for tolerance

iii). Tolerance on steel weight per meter

i). 0 – 10mm – +_0.7%

ii). 10 – 16mm +_0.5%

iii). 16mm & above – +_0.3%

49). Standard data for tolerance

iv). Tolerance for cutting length.

i). When the specified length is not given = _+75mm.

ii). When the length is given for cutting L = _+50mm.

### 50). Materials consumption per sqft

i). RMC –  0.05m3/-sqft.

ii). Cement –   0.5bags/-sqft.

iii). Electrical cost –   Rs.150/-sqft.

iv). Plumbing Cost –   Rs.140/-sqft.

v). Fire fighting Cost –   Rs.55/-sqft

I earnestly hope that these thumb rules have been both meaningful and useful to you.

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