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

Title of scriptLayout 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.

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 setting 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 About Spoken Tutorial project	The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
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Slide Forum for specific questions Do you have questions in THIS Spoken Tutorial? Please visit this site https://forums.spoken-tutorial.org 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.	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

Contributors and Content Editors

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