View source for Construction-of-Low-Cost-Houses/C2/Layout-and-Excavation-for-Foundation/English

'''Title of script'''Layout and Excavation for Foundation

'''Author: '''Dr. N. Varma, Chitra Devi, Madhuri Ganapathi

'''Keywords: '''Foundation soil, Excavation''',''' Layout plan, Tools for Excavation, Sign boards, spoken tutorial, video tutorial.

{|border=1
|| '''Visual Cue'''
|| '''Narration'''
|- 
|| '''Slide '''

'''Title slide'''
|| Welcome to this Spoken Tutorial on Layout and Excavation for Foundation.
|- 
|| '''Slide '''

'''Learning Objectives'''
|| In this tutorial we will learn about,
* Different types of foundation soil 
* Typical layout plan
* Tools for layout setting and excavation
* Setting the layout for foundation
* Process of excavation and
* Safety measures 
|- 
|| '''Slide '''

'''Prerequisites'''
|| To practise this tutorial, learners should be familiar with basic construction methods.
|- 
|| '''Types of foundation soil.'''

1a-blackcotton-soil.jpeg

1b.sandy soil.jpg

1c.Hard rock.jpg

1d.wet-clay.jpg
|| We will begin with types of foundation soil.

|- 
|| 2.Type-of- foundation- soil.png
|| The selection criteria for foundation depends on:

soil condition.

load from structure to be constructed

water table and other factors.
|- 
|| 3.Hard rock.jpg
|| '''Hard murum and hard rocks'''

Hard murum and hard rocks are the most suitable foundation strata.

In this there is minimum risk of soil settlement.

A 2 brick thick wall foundation with good quality bricks is required.

|- 
|| 4.soft-murum.jpg

5.Plinth-Beam.jpg
|| '''Sandy clay, soft murum and rock'''

These soils lose some strength when wet.

A 2.5 brick thick wall foundation with good quality bricks is required.

RCC band at plinth level has to be provided to prevent unequal settlement.

|- 
|| 6a.black-cotton-soil.jpg

6b.blackcotton-soil.jpeg

6c.black-cotton-soil-ontop.jpg

6d.black-cotton-soil-sandy-soil.jpg

|| '''Black cotton soil'''

Black cotton soil is not good for foundation.

It swells when wet and shrinks with wide cracks when dry.

If black cotton soil is available in shallow depth, it has to be removed.

RCC strip foundation and plinth band for brick wall has to be provided.

It will protect from unequal settlement. 

|- 
|| 7a.sandy soil.jpg

7b.strip footing.jpg

7b.strip footing.jpg
|| '''Sandy soil'''

Sandy strata are not good for foundation.

It changes volume considerably due to moisture.

Soil protection has to be provided to avoid high risk of soil erosion.

RCC strip footing and plinth band has to be provided.

|- 
|| 8.wet-clay.jpg

9.Dry-rubble-soiling.jpg

9a.wodden-compactor.png

9b.wooden-compactor-with measurements.png

10.clay-and-filled-soil.png

|| '''Clay'''

Clay has good strength when it is dry but it is very weak when it is wet.

There is a high risk for foundation settlement.

To prevent foundation settlement, dry rubble soling has to be provided.

Here, hard stone of 25 to 60 cm size with flat surface down is required. 

Compaction can be done for 3 days using a wooden circular block.

A Circular block of 35 cm diameter and 1 m height with 2 handles is used.

RCC strip footing and plinth band for unequal settlement has to be provided.

A 2.5 brick thick wall foundation using good quality bricks has to be built on such soils.

|- 
|| 11.filled soil.jpeg
|| '''Filled soil'''

Suitability of foundation on filled soil depends on type of soil and its compaction.

Proper compaction of soil is required.

RCC strip footing and plinth band for unequal settlement has to be provided.

|- 
|| Only Narration
|| '''Layout plan'''
|- 
|| 12.ground-floor.png
|| First we will discuss a typical 2 room layout plan.

Minimum carpet area admissible is 25 sq m.

In case of a 2 room house the first room preferably, has to be bigger in size.

Its size has to be 9 sq m, with a minimum width of 2.5 m.

Second room’s size has to be 6.5 sq m with a minimum width of 2.1 m.

Minimum area of individual kitchen may be 2.7 sq m with a minimum width of 1.5 m.

Minimum size of combined bath and WC shall be 1.8 sq m with minimum width of 1 m.

Width of the verandah may be 1.8 to 3.0 m.

Room sizes can be altered within provisions of National building code of India.

|- 
|| '''Slide '''

'''Tools'''
|| Tools for setting the layout and excavation.
|- 
|| 13a.iron-arrows.jpeg

13b.iron arrow.png
|| '''Iron arrows''' 

These are used to fix the points on the ground.
|- 
|| 14a.liness-pins.jpg

14b.lines-pins.jpg
|| '''Line and pins'''

Lines and pins are used for marking the lines on the ground. 
|- 
||15a.measuring-tape.jpg

15b.measuring tape.png
|| '''Measurement tape'''

Measurement tape is used to measure the dimensions on the ground. 
|- 
|| 16a.Diging Bar.jpg

16b.digging bar.jpg
|| '''Digging bar'''

Digging bar is used to loosen the soil.

|- 
|| 17a.pickaxe.png

17b.pickaxe.jpg

|| '''Pick axe'''

Pick axe is used to excavate hard soil and soft rock.

|- 
|| 18a.Chisel.jpg

18b.hammer.jpg
|| '''Chisel and hammer'''

Chisel and hammer are used to cut the rock.

|- 
|| 19a.hoe.jpg

19b.hoe.png
|| '''Hoe'''


Hoe is used to excavate soft or loosened material.
|- 
|| 20a.head-pan.jpg

20b.headpan.png
|| 

'''Head pan'''

Head pan is used to carry the excavated soil out of the site or to refill the site.
|- 
|| '''Slide '''

'''Steps for Setting the Layout '''
|| Steps for '''s'''etting the layout 


Site cleaning and

Demarcation of the center line on the site.

|- 
|| 21a.debris.jpg

21b.Cleared land.jpg

Make two images in to one image- combine
|| '''Site cleaning'''

Grass vegetation and debris if any has to be removed from the proposed building plot.

|- 
|| 22a.layout marked with iron pegs.jpeg

22b.layout-with-measurements.png

23.markings-white-lime.jpg
|| '''Demarcation of the center line on the site'''.

For rectangular layout up to 16 m length, setting out can be done manually.

Set all the building corners on the ground using iron arrows.

The adjoining lines on the ground should be perpendicular to each other.

For this a simple perpendicularity theorem is used.

Sum of the squares of two perpendicular lines is equal to square of the third line.

Mark center lines for all the load bearing walls on the ground using white lime.


All marking should be done according to the typical layout plan.

|- 
|| '''Slide '''

'''Excavation'''
|| Foundation strata have to be checked before the process of excavation.

|- 
|| 

24.Checking-excavation strata.jpeg
|| The foundation strata are checked using a crowbar. 

It shall be a minimum 50 cm depth in normal cases.

If the crowbar is not easily penetrating in the soil, the strata are hard.

Such strata are good for laying the foundation.

In case of weak soils, advice from the technical support system is required.
|- 
|| 25.losening-soil.jpg

26.Excavation.jpeg

27.foundation pit after excavation clay .jpeg

27a.Excavated foundation pit in hard moorum.jpg
|| Let us begin the process of excavation.

Loosen the soil using a digging bar and pick-axe.

Carry out the excavation using hoe.

Remove the excavated material.

Using a head pan, stack it beyond 2 meters or more.

This is to avoid falling of the soil in the pit again.

Carry out excavation up to 50 cm or more till hard strata is reached.
|- 
|| 28.work-in-progress.jpg

29a.precaution.jpeg

29b.Water on pit.png
|| Safety precautions during excavation

Placing sign boards in the construction site is a must.''' '''

For deep foundations, care has to be taken to prevent collapse of side walls.

During monsoons the excavated pits get flooded with water.


Care has to be taken to prevent drowning incidents in these pits. 
|- 
|| '''Slide '''

'''References '''
|| References

IS:1904-1986

IS: SP7-2005 National Building Code of India
|- 
|| '''Slide '''

'''Summary '''
|| With this we come to the end of this tutorial.

Let us summarize.


In this tutorial we have learnt about,
* Different types of foundation soil 
* Typical layout plan
* Tools for layout setting and excavation
* Setting the layout for foundation
* Process of excavation and
* Safety measures 
|- 
|| '''Slide '''

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|- 
|| '''Slide '''

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||  '''Slide '''

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|| Do you have questions in THIS Spoken Tutorial? 

Please visit this site 

Choose the minute and second where you have the question 

Explain your question briefly 

The Spoken Tutorial project will ensure an answer

You will have to register to ask questions

|- 
|| '''Slide'''

'''Acknowledgments'''
|| The Spoken tutorial project was established by the Ministry of education, government of India.   



|- 
|| '''Slide'''

'''Thank You'''
|| This tutorial is contributed by Dr. Narsingh Varma, Chitra Devi, Arthi Vardarajan and Madhuri Ganapathi from IIT Bombay.

Thank you for watching 
|-
|}