Estimating and Costing

Updated: May 15, 2020

Estimating and costing

Quantity survey- it means that calculation of quantity of required to complete the word concerned

specification- detailed specification give the nature, quality and class of work materials to be used in the various part of work quality of the material their proportions,workmanship And description of of execution of work.

site plan- it is a plan Drone for a particular construction showing its position with respect to approaching roads, main market and other permanent features in populated area

Some important term

1. plinth area- the built up cover area office building measured at floor level of any storey is called plinth Area.

wall area, porch, internal shaft (2m²), duct lift, staircase room, machine room etc. are included cantilever porch, external staircase, Terrance at first floor, additional floor for sitting In assembly building, theatres auditorium.

2. carpet area- the covered area usable space of room of any floor it is measured between wall-to-wall Ribbon building.


following area not include in carpet area.

1. wall area

2. Veranda

3. corridor and passage

4. entrance hall and porch

5. staircase and stair cover

6. lift shaft and machine room for lift

7. bathroom and lavatory

8.Kitchen and pantry

9. Store

10. Canteen

11. air conditioning duct and plant room

12. internal shaft hor sanitary piping


3. Floor area- plinth area - wall area


4. Setback area- setback area can be explained as the minimum open space required around any building or structure

Municipal regulations make it mandatory for a specific distance to be maintained between a building is being constructed on, in order to keep it away from road water bodies and other buildings.



5. circulation area- area that is helpful in movement of people through, arround and between buildings and other parts of the built environment.

lobbies, corridor , stair, lift, landing etc.


What is floor area ratio (FAR)

the area ratio is the relationship between total amount of usable floor area that of building has or has been permitted to you have and the total area of the the plot on which the building stands the ratio is is determined by dividing the total or gross floor area of the building by ghost food area of the plot.

Floor area ratio= (total building floor area/ gross plot area)


1. what is the floor area ratio for single storey building with plot area 1000 square metre floor area 500 square metre ?

Floor area ratio=500/1000 =0.5


2.Floor area ratio (FAR) horse food storey building with plot area 4000 square metre and floor area 500 square metre?

Floor area ratio=(500X4)/4000 =0.5


Estimation

Estimating is the technique of calculating for computing the various quantities and the expected expenditure to be incurred on a particular work or project

In case the fund available are less than the estimated cost, act the work is done in part or by reducing it or by the alternate specification, the following requirements are are necessary for preparing estimate

>> drawing like plan, elevation and section of important point

>> detailed specification about the workmanship & properties of Material

>> Standard 6 dual of rate of the current year.


Need of estimation

estimate give an idea of of the cost of the work feasibility can be e determined i.e whether the project would be taken of week the funds available or not

estimate gives an idea of time time required for the compilation of work.

Estimate is required to invite the tender and quotation and to arrange contract.

estimate is also required to control the the the expenditure during the execution of work.

decide weather the proposed plan message the fund available or not

Prosedure/ method of estimate

estimate involves the following operation

1. preparing detailed estimate

2. calculating the rate of of each unit of work.

3. preparing abstract of estimate


Data required for preparing estimate

1. drawing- if the drawing are not clear without complete dimension the preparation of estimate become very difficult. so it is very essential data required for estimate.

2. specification-

a) general specification- this gives the nature quality, class and work and material in general terms be used in various part of work it helps to form a general idea of building.

b) detailed specification- please give detailed description of the the various items of works laying down the quantities and qualities of materials, there proportions the method of preparation, workmanship and execution of work.


c)Rate:- for preparing the estimate the unit rate of each item off work are required.

i) For arriving at the unit rate of each item.

ii) the date of various materials to be used in in the construction

iii) the cost of transport materials.

iv) the wages of labour, skilled or unskilled mason, carpenter, majdur etc.


Complete estimate

a) cost of land- Actual cost of land, cost of serving, cost of verification of deed and execution deed ,Brokerage if any.

b) contingencies

c) legal expenses between owner and contractor

d) cost of construction - cost of labour, cost of material, Consulting Engineers.



work charged establishment

during the construction of a project considerable number of of a skilled supervisors, work, assistance, watchmen etc are employed on temporary basis.

the salaries of this person are are drawn from lump sum amount allotted towards the work charged establishment. which is charge directly to work .A lump sum amount is is 1.5 to 2% of the estimated cost is provided towards the work charged establishment


lump sum

while preparing an estimate it is not possible to work out detail in case of petty items, items other than civil engineer search items is lump sum item

the following are sum of lump sum item in the estimate

i) water supply and sanitary arrangements(8%)

ii) electrical installation

iii) architectural features

iv) contingency and unforeseen item (3-5%)

v)Work charged establishment



In general certain percentage on the cost of estimation is allotted for the above lump sum item Even if sub estimate prepared or at the end of a execution of work, the actual cost should not exceed the lump sum amount provided in the main estimate.


Measurement of materials and works

the limit of measurement are mainly categorised for their nature shape and size and for making payment to the contractor and also show the principal units of measurement normally consists of the following.


a) single units work like doors, Windows, trusses etc. are expressed in number.

b) what's consists of linear measurements in length like cornice, fencing, handrail, band of specified with etc. are expressed in running metre.

c) what consists of areal surface measurement in area like plastering, white washing, partitions of specified thickness etc are expressed in square metre.

d) work consist cubical contains with involve volume like earth work, cement, concrete,

Masoenary etc are expressed in cubic metre.



important item of work

Earth work- it is measured in in m³ but payment is done in in 100 m³

in foundation we use lean concrete or weak concrete.

general thickness of concrete is 20 to 45 cm

Soiling- when the soil is soft/ bad then one layer of dry weak stone is applied below the concrete paste. this process is called soiling


DPC- damp proofing course

thickness varies from 2 to 2.5 cm rich cement mortar M20 (i.e- 1:1.5:3)


Pointing and plastering

thickness of plastering is 12mm

Plastering and Pointing is in metre square

following are the deduction condition for opening

no deduction made for small area 0.5m²

0.5- 3m² For opening area, then one side deduction

for opening area greater than 3m² then deduction is made both side.


Rule of measurement

the rule of measurement of each item are are invariable described in IS-1200

Some importance rule are as follows

i) measurement shall be made for finished item of work and description of each item shall include material ,transports, labour ,fabrication tools, and plant and all types of overhead for finishing the work in required shape, size and specification.

ii) in booking the orders shall be sequence of length, breath, height or thickness

iii) all work shall be measured subject to to the following tolerance

linear measurement shall be measured to the nearest 0.01m

area shall be measured to the nearest 0.01 sqm

Cubic contain shall be worked out to the nearest 0.01 cum

Administrative approval

for any project required by the department an approval so sanction of the component authority with respect to the cost and work is necessary at the first instance on an approximate estimate

thus administrative approval denotes the formal acceptance by the administrative department concerned of the proposals for incuiring expenditure.


Technical sanction

it means the section and order by the the component authority of the department for the detailed estimate design calculation quantities of work rate and cost of work.

after technical sanction of the estimate is received the work is then taken up for construction

after this financial department sanction the expenditure.


Type of estimate

preliminary or approximate estimate is required for studies of various aspect of work of project and its administrative approval

it can decide in case of commercial project whether the net income on justifies the amount invested or not.

the estimate is accompanied by report duly explaining necessity and utility of the project and with a site or layout plan


Following are the method of approximate estimate

a) Plinth area method

b) cubical contents method

c) unit base method


Plinth area method- the cost of construction is determined by multiplying plinth area rate

as per IS-3861-1966 following area are used

i)area of walls at floor level

ii)internal shafts of sanitary installation not exceeding 2.0m2, lift,AC ducts etc.

iii) area of barsati at terrace level barsati means any covered space open on one side constructed on terraced roof with is used as shelter during rainy season.

iV) porches are non cantilever type


Following area not included

area of loft

unenclosed balcony

architectural bands, cornices etc.

domes, Tower ,projecting above terrace label

box covers and vertical Sab breakers


b )cubical contents method-this method generally used for multi storey building, it is more accurate that the other two method viz, plinth area method and unit base method.


c) unit base method

cost of structure is determined by multiplying the total number of units with the rate of each item.

in case of schools and colleges the unit considered to be as one student and in case of hospital the unit is one bed.

the unit rate is calculated by dividing the actual expenditure incurred or cost of similar building in nearby locality by the number of units.

Service units for different types of buildings are considered as below : [S - 14]


(a) School – per student

(b) Hospital – per bed

(c) Cinema theater – per seat

(d) Stadium – per seat

(e) Reservoir – Capacity in litre – per litre

(f) Prison – per cell

(g) Hotel – per room

(h) Stable – per animal

(i) Office – per room or cubicals

(j) Large apartment – per tenament

(k) Restaurant – per seat

(l) Bridge – per km.


Detailed estimate

it consists of working out qualities of various item of work and then determined the cost of each item this is prepared into two stage.

Detail of measurement and calculation of quantities

the complete work is divided into various item of work such as Earth work, concreting , brickwork,RCC plastering etc.The detail of measurement are taken from drawings and entered in respective column of prescribed proforma. the quantities are calculated by multiplying the value that are in number to date of column

Abstract of estimated cost

the cost of each item of work is work out the quantity that already computed in the detailed measurement from at workable rate.

but the total cost worked out in prescribed form is known as abstract of estimated form .



• Types of detailed estimate :

(1) Revised estimate,

(2) Supplementary estimate,

(3) Revised and supplementary estimate,

(4) Annual maintenance or repair estimate.


Revised estimate

when the sanction Estimate exceed by 5% either due to rate being found insufficient or due to some other reason a fresh estimate prepared which is called revised estimate.

A comparative statement on the last page of estimate is attached giving their the reason of the increase of the cost of each item.


Supplementary estimate

this is fresh detailed estimate in addition to the original sanction estimate prepared when additional work are deemed necessary during the progress of work to supplement the original work

the Abstract of cost should show the amount of the original sanctioned estimate as well as the Supplementary amount of the original sanctioned estimate as well as supplementary amount for which sanction is required


Revised and Supplementary Estimate

When the work is practically abandoned and estimated cost of remaining work is less than 95% of the original work, or less than 90% of the original sanctioned

estimate or when there is material deviation and changes in design. Then the

amount of original estimate is revised by the competent authority.

A supplementary and revised estimate is prepared and fresh technical sanction of

the competent authority is obtained.



Annual repair estimate

In order to keep building and roads in perfect condition, annual repair should be carried out as follows

In case of a building whitewashing wiring and painting of door and Windows cement plaster repair ( inside & outside) repairs floor etc. in no case this annual repair amount should increase more than point 0.5% to 2% of the capital cost of building.

In case of road filling patches etc


Method of taking out quantities

The quantities like earthwork Foundation concrete, brickwork in plinth and Super structure etc can be worked out by any of the following methods

a) long wall short wall method

b)Central Line method

c)partly Central Line and short wall method


a)long wall short wall method

in this method the wall along length of the room is considered to be long wall while the wall perpendicular to long wall is said to be short wall

To get the length of long wall or short wall Calculate the first Central Line length of individual walls

Then the length of long wall ( outer to Outer) may be calculated after adding half breadth of each end to its Centre line method.

the length of short wall measured into in and may be found by deducting breath from its Central Line length of each end

The length of long wall usually decreases from earth work to brick work in superstructure while the short was increases.

These length are multiplied by breath and depth to get quantities.


b)Centre line method

this method is suitable for wall of similar cross-sections.

here the total Centre Line length is is multiplied by breadth and depth of respective item to get the total quantity at a time.

When cross walls or partitions or Veranda wall join with the main wall the centre line length gets reduced by half of breath for each Junction.

such junction or joints are studied carefully while calculating total Centre line length the estimates prepared by this method are most accurate and quick.



c)Partly Centre line and partly long wall short wall method

this method is adopted when external (i.e around the building) wall is same thickness and internal wall having different thickness.

in such cases, Centre line method is applied to external walls and long wall short wall method used to internal walls

this method suits for different thickness wall and different level of foundations.

because of this reason all engineering department are practicing this method.


Analysis of rate

the process of determining the rate of any work in engineering project like earth work, brickwork,plastering painting etc is called rate analysis.

the rate of these work further help in in determining the cost of particular work and it turn the cost of the project


Need of rate analysis

1. to determine the actual cost per unit item.

2. to work out the economical use of material and process in completion of particular work

3.To calculate cost of extra item not included in the contract Bond but are required .

4.to device the schedule of rates as per the present cost of material aur labour or Technology.


Factor affecting rate analysis

1. Specification of work and material ( quality, proportion etc)

2. Quantity of materials and their cost.

3. Cost of labour and their wages.

4. location off site work and is distance from source and there conveyance charges

5. Profit

6. overhead establishment charges.


The analysis of rates is worked out the unit payment of the particular item of war under to head

1 .material

2. Labour

cost of item at work = material cost+ labour cost


other items included are

1. tools and plants = 2.5% to 3% of the labour cost

2. transportation cost for more than 8 kilometre is considered.

3. water charges = 1.5% to 2%

4.contractor profit up to 10%


Cost of material

1. it is taken as the cost include while material is delivered at site work

2.it is inclusive of first cost (Cost of orign) conveyance charges, taxes etc.


lead statement

the distance between the source of of availability of material and construction site it is known as lead and measured in kilometre

the conveyance cost of materials depend upon lead

the lead statements gives total cost of materials per unit item including first cost,conveyance loading, unloading












Lead

during the earth work the average horizontal distance between the centerline of excavation to

the the centre of deposition is called lead


Lift

during Earth work, the average hight through which soil has to be lifted from source to the place of spreading is called lift

the first list is taken up to 2 metre

the extra lift is counted for 1 metre after the the first lift and so on.


cost of labour

the labour is classified as as

skilled first class

skilled second class

Unskilled

30% of the skilled labour provided in the data may be taken first class and remaining 70% as second class.


Contractor’s profit

this is 8 to 10%off the net profit that is allowed for contractor

10% is is not allowed a steel and cement


overhead costs

this comes to 6 to 8% of the total cost of the project.

these include all the indirect expenses incurred during the project


Task or turn work

the capacity of doing work bi a skilled labour in the form of quantity of work per day task or turn work

more common developed or urban cities as compared to small town.


general specification

this gives the nature and class of the work and material to be used in in in in various part of work from the foundation to the the superstructure.

it is short description of different part of work specifying, material, proportion, qualities etc.

general specifications gives general idea of the whole work or structure and are useful for preparing estimate


excavation feeling and backfilling

Include

excavation of foundation, trenches ,pits and over areas, correct to dimension given in the drawing

stacking the useful material as directed within the lead specified.

feeling around the foundation and into the plinth with selected useful excavated Earth

Disposing of the surplus Earth or material within specified lead.

finishing the surface to proper levels, slopes and camber etc all completed


site clearance

before the earth work is started the area coming under cutting and filling shall be removed up to distance 150 metre outside the periphery of the the area under clearance


Rules and vegetation clearance

the roots trees shall be removed to a minimum depth of 60cm below ground level or minimum 30cm below formation label which ever is lower


setting out and making profile

masonry or concrete pillar will be elected to a suitable points in the area to serve as benchmark for the execution of work.


The ground level shall be taken at it 5 to 15 metres intervals in uniformly sloping ground and exposure distance

the item in the schedule of quantities shall specify the excavation in in trenches or over areas


excavation of foundation trenches- depth of trenches for foundation not exceeding 1.5 metre in width or 10 sqm


Excavation over area- excavation exceeding 1.5m in width As well as 10 square metre on plan ( excluding trenches for pipe cable) etc and exceeding 30cm in depth


Classification of earthwork

1. all types of soil, murum boulders

this includes, earth, murum, top deposit of agriculture soil, reclaimed soil, clay, send or any combination of soft hard muram

2.excavation in soft rock

this includes all material which are are rock or hard conglomerate ,all decomposed wethered rock, Highly fissured rock, old masonary boulders bigger than 0.03 m3 in volume but not bigger than0.5 m3 and other varieties of soft rock which can be remove only with pick axes , crow bar,wedges and hammer with some difficulty.


mode of measurements

1. all excavation in areas having death more than 30cm pits trenches etc Shall be measured as surface of excavation on square metre basis.

2. excavation in areas having depth less than 30cm shall be measured as surface of excavation on square metre basis.

3. where direct measurement of rocks excavation are not possible volume of rock can be calculated on the basis of length, breadth and depth of stacks made at side.

4.the net volume shall be work out by reducing it by 40% taking the void into consideration as 40%



Valuation

valuation means fixation of cost or return expected of a building, engineering structure projects ( government or private) at present days rate

the value of structure may be more or less depending upon the the present utility of a structure.


necessity of valuation property

i).Rent fixation ( generally taken as 6% of the valuation of the property)

ii).For buying and selling

iii). Acquisition of property of government

iv)To mortgaged with bank or any other society to raise loan.

v) for various taxes to given and fixed buy Municipal committee

vi) insurance


factors considered in valuation

types of building

Location

building structure and durability

the quality of materials used in construction

size of building


Value

present day cost of Engineering structure ( saleable value)

it may be higher or lower the cost


Cost

original cost of construction

it is used to find out the loss of value of property due to various reasons


gross income

it is the total amount of the income including all recipt from various sources

the outgoing, the operational and collection charges are not deducted in this.


net income

it is the amount left after deducting all the outgoing , operational and collection expenses from the gross income eg- guard, electricity etc


Outgoing

the expenses that are required to be e incurred in order to maintain the revenue of the building


various outgoings are

Taxes

these are annual taxes paid by the the owner such as wealth tax, property tax and Municipal tax ( varies from 10 to 25% of net income)


Management

up to 10% gross revenue is kept aside of these expenses.

these include chaukidar, sweeper etc applicable only for big building or apartments


Repairs

1.5% of the total construction is set aside for annual repair of the building.

this repair are must to maintain the building.

it is also calculate 10% of the gross income.






I- Annual installment required

N- number of years creating sinking fund

I-Rate of interest expressed in decimal

S- amount of sinking fund



Miscellaneous

this is again suitable for big buildings lighting of common place, Expenditure of of lift man etc are to be paid by owner


loss of rent

this is also an outgoing in case a building is not fully occupied the tenants

this has to be deducted from gross income



Insurance

premium given against fire or theft policy



type of value

market value

scrap value

Salvage value

rentable value

book value


market value- it is defined as the value which a property can fetch when sold out in an open market

this value is variable, depending upon the will to buy or sell


scrap value- it is defined as the value of materials of dismantled buildings

it is usually 10% of the total cost of the construction.


Salvage value

it is the value of building at end of utility period without being dismantled.


Rentable value

it is the net annual letting value of a property obtained by after deducting the amount of yearly repair from gross income.


Book value

it is the amount of a property in the books after allowing necessary depreciation year wise.

The book value independent of market value


Obsolescence

The value of property decreases if you style and design are outdated i.e room not properly set, thick wall, poor ventilation etc. the reasons of this is fast changing techniques of construction, design, ideas leading to more comfort etc.


freehold property

any property which is incomplete possession of the owner is known as freehold property

the owner can use the property in the Any way he likes .But he will have to follow constraints fixed by town planners or municipality before doing any construction.


Leasehold

if a property given to some person on early payment basis bi free holder then property is called leasehold property and the person who take the properties is called lease holder

in case of building the lease is for 99 year to 9 year


Easement

an honour getting over the property of another person the following facilities are known as Easement

facility of running water and sewer pipe through other land

facility of air and light

facility of drainage of rainwater

facility of access


One who gives facility is known as servant while one who accessThe facility is known as as dominant owner



building cost index

a building cost index, indicate the increase and decrease of the cost above the costat a certain base year and is expressed by percentage rise and fall


capitalised value

it is defined as the amount of money whose annual at the highest prevailing rate will be equal to the net income received from the property.

to calculate the the capitalised value it is necessary to know the highest rate of interest Prevailing on such properties and net income from the property.


Annuity

the return of capital investment in the shape of annual installments( monthly, quarterly, half yearly, yearly) for a fixed number of of year is known as annuity


Depreciation

a structure after sometime gradually losses some of its value due to its constant use and some other similar regions such as


the property in neglected condition

the property being away from school and market

design being out of fashion

poor specifications followed which requiring maintenance

the loss thus involved in the value of properties known as depreciation





D- depreciated value

P- present value

rd- fixed percentage of of depreciation

n- number of year the building has been constructed.



various method of valuation

depreciation method of valuation

valuation based on cost

valuation based on Profit

valuation by development method

rental method of valuation


depreciation method of valuation

in this method, structure is divided into four parts for calculating depreciation

first method





D = depreciated value

P = present value

rd- fixed percentage of of depreciation

n- number of year the building has been constructed.



Second method




D = depreciated value

C = original cost

S = scrap value

n = life of the property


Value based on cost

in this method, the actual cost of the construction is found out and valuation is done after considering depreciation and considering the type of construction, and design of the construction.


valuation based on profit

under the subhead elevation of cinema, theatre, hotel, Bank, Big Shop etc. located at suitable places is done where profit is of capitalised value.

the capitalised value is calculated by multiplying years purchase with net profit

the net profit is worked out after detecting all possible outgoing and expenditure from the gross income

in such cases the cost will be too high as compared with the cost of construction actually incurred.


Value by development method

this method is also used for working out the value of a building .

the certain cases, some addition, alteration and improvement are carried out which increases the cost of the building.


rental method of valuation

in this method the rent of building is used as the base for calculating the value of building


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