10 LEVELS OF CONSTRUCTION

S. Shanthi

epgp books

 

 

 

Introduction:

 

Basic needs of human being include food, shelter and clothing. Shelter includes construction of buildings to fulfill the requirements of protection from natural clarity. Construction includes different levels leading to

 

Objectives:

  1. To impart knowledge on levels of construction
  2. Awareness on different methods of construction on structural elements
  3. To impart knowledge on functions of structural components
  4. To sustain quality of Construction

Construction:

 

It is the process of constructing building or infrastructure in a location. It comprises of three main stages namely planning, designing and financing.

 

Process of Construction:

  • Funding
  • Brain storming with contractors
  • Enquiry with promoters
  • Rough idea about the executors
  • Enquiry with neighbors
  • Rough estimation of the project
  • Schematic refinement
  • 3D model developing
  • Plan authorization

Stages of Construction

 

Planning:

 

It involves determining the resources required for the project namely

  1. Materials required for construction
  2. Time period for completion
  3. Suppliers of materials
  4. Human resources – labors needed
  5. Equipments required

Designing:

 

It involves creation of plan for execution according to the convenience. Mainly this is done with consultation of the customer. Nowadays 3D walk-in through of the plan is being showed to the customers from to have an idea of their plan, ambience, utility services, and architectural view.

 

Financing:

 

This is the most important part of construction since without financial commitments nothing can be done. So at the early stage of the project built up area, materials to be used, all interiors, finishes and facilities required are decided and a rough estimate is worked out. Usually 5% increase in cost is being added in consideration with period of completion. Primervera Software is been used widely in consulting offices to do accurate estimation. Financial commitments may be taken care through bank loans, tenders etc.also.

 

CASE STUDY

 

Construction of a Residential Building

 

Paper works before the start of actual construction includes the following steps

  1. Preparing plan of the house as per the requirements of costumer.
  2. Estimation of total cost of the building including material, labors etc.,
  3. Getting approval of the drawing from concerned authorities, which can be done through PDCR online submission.
  4. Arranging for bank loans , tenders etc.,
  5. Setting a team of labors either on basis of hiring or on daily basis for construction work.

LEVEL 1

 

Foundation:

 

A foundation is substructure of a building structure that transfers its loads to the ground. A building should have a strong foundation if it is to stand for a long time

 

Types of foundations are

  1. Shallow foundation – depth of footing is less than width of footing . e.g – individual , strap, combined , mat etc., foundations
  2. Deep foundation – depth of footing is greater than width of footing. Pile , Caisson foundations. Depending on type, functionality of building, type of soil type of foundation is decided.

Marking of foundation using Centre line method

  1. The proposed building site is first cleared of all junks, plants and trees.
  2. Prepare centre line sketch for the plan
  3. Set out straight line greater than length and width of the building
  4. Positions, width and breadth of foundation/columns are also marked on the ground as shown in fig 1.
  5. Measure the width of the foundation and mark it along the strings set out for two opposite walls. Then set out a string between these two points and fasten the ends with pegs. Plumb bob is used to check that each peg is directly beneath the outside foundation line.

Earth work

 

Excavation of the earth along the boundaries of the foundations are done as per the drawing defined length and breadth and depth. Generally excavations are made with some clearance to the size of foundation say about 6” on either side as shown in fig2.

 

Usually depth of excavation is been decided from the neighborhood evidences. Technically it depends on the type of soil. It various from four foot to 6 foot or 2.5m to 5.5m usually. The main consideration in deciding depth of foundation is, the building should rest on hard strata so that building load can be distributed to ground safely without any settlement.

Concreting of Foundation:

 

First level of foundation is checked before starting concreting work. It must be noted that levels of foundation throughout the building must be at same. Any difference in levels causes differential settlement leading to failure of building.

 

For a depth of three inches concrete with 40mm coarse aggregate is poured and ramped which forms the base. This base act as a contact layer for distribution of load from building to ground (soil) evenly as shown in fig 3.

 

Over the base a mat with column steel rods are placed vertically as shown in fig 4 and concrete of ratio 1:6:10 are poured for a depth of six inches. The base mat is made of steel bars on both the directions. Concrete mix is decided usually concrete of ratio 1:4:8 is used for foundation it can also be extended to 1:5:10 or 1:6:10 ratio.

 

o  The ratio of concrete means

 

1 part of cement per cubic concrete

4 parts of coarse aggregate namely sand per cubic concrete and

8 parts of coarse aggregates locally known as “Jally”

 

Once the mat is filled with concrete form work of size to foundation width and concrete of ratio 1:5:10 is poured. This forms a pedestrian to a height of six inches

 

Over the pedestrian form work is made for the width of column and concreted up to level of the ground forming the base of the column as shown in fig 4.

 

Floor levels of a house are usually higher than the natural ground. The rise from ground level is treated as thickness of floor and is filled with soil/ quarry dust and compacted.

 

The remaining sides of the excavation are filled with excavated soil up to the ground level.

 

LEVEL 2

 

Construction of Plinth Beam:

Plinth Beam:

It is a beam constructed at the ground level forming base course of wall. Its function is to evenly distribute building load to ground through columns constructed above it as shown in

 

fig 5.

 

Plinth area:

It is also known as Floor Area or Carpet Area or Built-Up Area or Plinth Area. It is the total area ustilised for utility in a building.

Construction of plinth:

 

Once the foundation is completed then plinth beam of width 9” and depth 9” with reinforcement of steel is built over the ground over which walls are constructed. Depth of the plinth beam is either filled with soil compacted or quarry dust. This forms the base for flooring. Since the flooring is in contact with soil there are chances of termites entering into the building this can be avoided by providing termite coating though painting the plinth beam. There is also another protection needed at this level namely damp proofing as shown if fig 6 since the moisture of the soil below might cause dampness to the walls causing damages and deteriorations to the structure.

Form work:

 

It is the mould for a structure to pour fresh concrete and form the required shape and size.

 

LEVEL 3

 

Framed Structure:

 

It is connecting together horizontal vertical and flat structural components namely beam, column and slab to safely distribute building load to ground and also to act as a skeleton of the building as shown in fig8.

From the fig 7 it is noted that weight of head (slab) is transferred to shoulder bones(beam) and weight from them is transferred to vertical spinal bones (column) and these loads are transferred to ground through pelvic girders and thigh bones to heel bones (foundation). Thus weight from slabs to beams and from them to columns then distributed to soil through foundation. This shows the importance of framed structure.

 

Column :

 

It is structural component of a building which lies vertically extended from the foundation. It carries load from the horizontal structural members. Normally it is reinforced concrete structure (R.C.C).

 

Beam:

 

It is the horizontal structural member which forms a base for roof (slab) and carries load from slabs. It is also a reinforced concrete structure.

 

Slab:

It is the flat structural member covering the entire built up area. It rests on the beam. It is a reinforced concrete structure.

Overview of construction of framed structure

 

The columns from the foundation are extended to the height of the lintel level ie normally at seven foot (7’) with the help of formwork and concreting. At the lintel level Lintel beam is constructed along with the sunshade connecting all the columns of the building as shown in the fig 9.

 

Above the lintel level column is extended to roof level say about 3’ from lintel beam. Above the column at 10’ beam is constructed across every columns connecting them horizontally. Slab connecting all the columns and beam is constructed above the beam to give shelter to the building as shown in fig 8. Thus finishing the construction of framed structure.

 

LINTEL:

A horizontal R.C.C. beam built across the top of doors or windows.

 

Opening for doors and windows of a building need to be supported with lintels as shown in fig 9.This can be done by constructing beams at the top of these opening connected horizontally from the columns. Its main aim is to carry loads of the building above the openings and prevent it from acting directly on the door /window frames and prevent it from causing failures.

 

ROOFING (Slab):

 

There are many types of roofing

 

Depending on materials

  1. Asbestos roofing
  2. Concrete roofing
  3. Sheet roofing
  4. Truss roofing
  5. Tile roofing
  6. Thatched roofing

Depending on shape

  1. Flat roofing
  2. Sloped roofing
  3. Arch roofing

Type of roofing depends on the customer wish, purpose of building, budget etc.,

 

First form work is made above beam connecting the beams and columns of the entire plan using either steel sheets or wooden planks. They are supported to ground using props as shown in fig11. Then reinforcement of steel rods binded with steel wires running in both the directions are placed above the formwork with cover blocks kept in between them to maintain the thickness of slab as shown in fig10 . The cement concrete of 1:3:6 is poured into the form work and ramped with the help of rods so that concrete fills all the corners of the slab. This setup is left for over 28 days and is cured by stagnating portable water by ponding to gain strength, on the 28th day the inner props are removed first then the outer near the beams and columns are removed. Usually the thickness of slab ranges from 100 to 125mm.

 

Precautions to be followed in formwork for roofing

 

No gaps should be seen in between the sheet/planks Sheets must be oiled properly so that when removing concrete should not stick to the sheets  Papers/ felts etc., should not be used for filling the gap in between the sheets

 

Sheets should be properly supported to the ground while concreting so that it does not impropriate the shape

 

Materials for formwork should be such that it should not absorb water, should be stiff to resist the concreting load, should have smooth surfaces.

LEVEL 4

 

MASONRY WORK

 

Constructions of brick wall in between the columns are done as shown in fig 12. Masonry works are carried with cement mortar with 1:4 to 1: 6 ratio ie 1 part cement and 4 or 6 part of sand. First a line of mortar is placed over the plinth beam and over it bricks are arranged in such a way that joints are not continuous. While using bricks for construction it should be kept wet by soaking it in water for one hour before usage. Verticality of wall is checked using plumb bob.

After construction of walls in between the columns it is cured for minimum period of one week using portable water by means of pipe hose. This would help the cement mortar bonding in between the courses of bricks strong in strength. Openings for doors and windows as per plan are left open while constructing walls.

 

LEVEL 5

 

Flooring:

 

It is the lower surface of a room, on which one can walk.

 

Types of flooring includes

  1. Cement concrete floor
  2. Brick flooring
  3. Tile flooring
  4. Mosaic Flooring
  5. Murom / mud flooring
  6. Wooden flooring

All these types depend on the customers wish and also the budget and the functionality of the building.

 

Construction:

 

Once the plinth beam is constructed two to three rows of rubble masonry of brick masonry is built over it. This forms thickness for base course of flooring. The total depth is partially filled either with soil or quarry dust and the remaining with 40mm metal concrete.

 

Thus strong and leveled base surface is formed. Over it cement mortar of 1:3 to 1:4 mix is laid for a thickness of 3mm in order to get a smooth surface. This forms flooring for a building and depending on required type of floor by the customer floor finish is laid over it.

 

Floor finish:

 

Flooring can be either left with cement mortar coated with cement slurry known as cement flooring or it can be even finished with natural stones e.g marble, granite etc., and artificial concrete tiles such as vetrified , sahabath etc., stuck on it for the ambience purpose.

 

Qualities of floor finish

 

It should be durable Noiseless

Should have ambience Water repellent

Fire resistant

Low maintenance cost

 

Types of floor finishes

Resilient – e.g vinyil , wood , rubber flooring

Hard – e.g – marble, granite, mosaic etc., flooring Smooth – e.g – tile flooring

 

 

LEVEL 6

 

Plastering:

 

Generally to prevent moisture entering the building, and also for ambience the internal walls and external walls are plastered using cement mortar. Mortar for plastering work used generally is of 1:3 or 1:5. Plastering thickness must not be more than 0.75 inches as shown in fig 13.. While plastering it must be noted that the cement mortar is not neither stiff nor lean, because consistency of mortar influences strength of it .

 

First surface of brick wall is made rough by combing it with brush. Then one coat of plastering with lean mix is splashed over the surface so that the mortar adheres to the surface of the wall roughly. Then the second coat with correct proportion mortar is applied on the wall surface and leveled with long light wooden bars. W is leveled and should ensure that the surface is leveled and smooth in nature.

CURING:

 

The process of sprinkling water on the constructed construction components such as beams, columns, slabs, walls etc made of concrete/ or cement mortar is known as curing. It serves two purposes namely

  1. Prevents the loss of moisture from concrete
  2. Maintains favorable temperature for hydration before attaining hardened stage of concrete.

 

Types of curing

 

Curing can be done by

  1. Ponding
  2. Steam curing
  3. Gunny Bags
  4. Sprinkling of Water
  5. Membrane Curing

Depending upon type of building to be constructed types of curing also changes. Normally ponding is followed at roof curing, gunny bags at columns and beams, sprinkling of water on plastered walls.

 

LEVEL 7

 

SERVICES:

 

Services are needed for every building irrespective of type of building. Different types of services are provided during construction. These are electricity supply, gas supply, water supply, sanitary etc.,

 

Electricity supply:

 

Conduits for electricity supply are fixed on the walls before plastering, for fans conduits are fitted on the roof before concreting.

 

Water supply:

 

Plumbing works are done after the masonry walls are built for water supply. Pipe lines for wash basin, bath room fittings and for other needs are done on the walls by breaking the bricks.

 

Sanitary:

 

Toilets are necessary irrespective of type of building constructed. While constructing flooring level for toilets are lowered by one foot. ‘P’ or ‘S’ trap pipes are fitted and packed tightly with filling all its sides. Pipes from toilets are connected to the central sanitary pipe through floors before concreting. Water proof coating is applied in the toilet room walls and on floors to prevent moisture entering the walls causing dampness.

 

Gas lines:

 

Gas lines are fixed outside the kitchen, in case provisions are given separately. Gas line remains open in air. These facilities are necessary only for residential, food industries etc.,only.

 

Conclusion:

 

Scope of this module is to familiarize you with different levels of construction which help to supervise any building anyone comes across in their lifetime. Knowledge on basicterms of construction would help them to easily communicate with contactors/ promoters regarding terms and conditions of contract. Will be able to examine risks and responsibilities involved in construction activities, understand residential, commercial etc. any type of building construction systems , materials and practices, Integrate plans, specifications and other construction documents, able to do detail quantity estimation.

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