SPECIFICATION AND ESTIMATION INNOVATIVE WORK

NAVEEN KUMAR S

ACE10UAR021

4th yr,SEM 8

ACE,HOSUR

TYPES OF ESTIMATON?

1. Preliminary or approximate estimate.

2. Plinth area method

3. Cubical contents methods

4. Unit base method

5. Abstract Estimate

6. Detailed estimate

7. BOTTOM UP METHOD

8. SQUARE FOOT ESTIMATES

9. Final Estimate or Annual repair

PRELIMINARY OR APPROXIMATE ESTIMATE:

Early in the planning stages of a project, both owners and designers need,

and often demand, an indication of the cost of the project at completion.

Since the project has not yet been designed, estimates prepared at this time

have a low expectation of accuracy. Names sometimes used to describe such

estimates include preliminary, ballpark, blue sky, seat-of-the-pants, and order of

magnitude. One of the important purposes of these preliminary estimates is to

provide information to an owner or client so that a decision can be made to

proceed with the project. Preliminary estimates are often made in less than two

hours.

The expected accuracy is no better than within 20-30%.Project

comparison is a method of preparing preliminary estimates when cost data for

comparable completed projects is available.

Preliminary or approximate estimate is required for studies of various aspects of

work of project and for its administrative approval. It can decide, incase of

commercial projects, whether the net income earned justifies the amount

invested or not. The approximate estimate is prepared from the practical

knowledge and cost of similar works. The estimate is accompanied by a report

duel explaining necessity and utility of the project and with a site or layout

plan. A percentage 5 to 10% is allowed for contingencies.

The following are the methods used for preparation of approximate estimates.

a) Plinth area method

b) Cubical contents methods

c) Unit base method.

a) Plinth area method:

The cost of construction is determined by multiplying plinth area with

plinth area rate. The area is obtained by multiplying length and breadth (outer

dimensions of building). In fixing the plinth area rate, careful observation and

necessary enquiries are made in respect of quality and quantity aspect of

materials and labor, type of foundation, height of building, roof, wood work,

fixtures, number of stores etc., As per IS 3861-1966, the following areas include

while calculating the plinth area of building.

• Area of walls at floor level.

• Internal shafts of sanitary installations not exceeding 2.sm, lifts, air-

conditioning ducts etc.,

• Area of barsati at terrace level:

• Barsati means any covered space open on one side constructed on one

side constructed on terraced roof which is used as shelter during rainy season.

• Porches of non-cantilever type.

• Areas which are not to include

• Area of lofts.

• Unenclosed balconies.

• Architectural bands, cornices etc.,

• Domes, towers projecting above terrace level.

• Box louvers and vertical sun breakers.

b) Cubical Contents Method:

This method is generally used for multistoried buildings. It is more accurate

that the other two methods viz., plinth area method and unit base method. The

cost of a structure is calculated approximately as the total cubical contents

(Volume of buildings) multiplied by Local Cubic Rate. The volume of building is

obtained by Length x breadth x depth or height. The length and breadth are

measured out to out of walls excluding the plinth off set. The cost of string

course, cornice, corbelling etc., is neglected. The cost of building= volume of

buildings x rate/ unit volume.

c) Unit Base Method:

According to this method the cost of structure is determined by

multiplying the total number of units with unit rate of each item. In case 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 the nearby locality by the

number of units.

ABSTRACT ESTIMATE:

The cost of each item of work is worked out from the quantities that

already computed in the details measurement form at workable rate. But the

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

estimated form. 4%of estimated Cost is allowed for Petty Supervision,

contingencies and Unforeseen items

DETAILED ESTIMATE:

The detailed estimate should accompanied with

i) Report

ii) Specification

iii) Drawings (plans, elevation, sections)

iv) Design charts and calculations

v) Standard schedule of rates.

Factors to be considered While Preparing Detailed Estimate:

i) Quantity and transportation of materials: For bigger project, the requirement

of materials is more. Such bulk volume of materials will be purchased and

transported definitely at cheaper rate.

ii) Location of site: The site of work is selected, such that it should reduce

Damage or in transit during loading, unloading, stocking of materials.

iii) Local labor charges: The skill, suitability and wages of local labors are

considered while preparing the detailed estimate.

BOTTOM UP METHOD:

The bottom-up method is considered to be the most accurate method for

generating project estimates. It is used to determine budget or definitive

estimates during the planning phase and at the start of each project stage.

The method uses the Work Breakdown Structure (WBS) developed during the

planning stage of the project. Estimates are created for all tasks at the lowest

level of the WBS and then these are accumulated to determine the estimates

for the whole project.

The consensus technique* is usually used to obtain task estimates for the

low level tasks on the WBS, because as well as producing reliable estimates it

also builds active involvement, cooperation and commitment. Experts with the

skills required to perform the work should be included in the estimating process.

One disadvantage of the bottom-up method is that it is much more

time-consuming than other methods.

SQUARE FOOT ESTIMATES:

Square foot estimating is another method of developing a preliminary estimate

based on historical data. This technique is effective in preparing advanced

preliminary estimates when features of the proposed project are known, but

not yet designed. To use this method, it is only necessary to know the type of

building or facility and the proposed number of square feet. Other unit

measures such as the number of beds for a hospital, or number of spaces for a

parking garage are sometimes used instead of square feet, but the basic

method for determining these estimates is the same. Annual cost data books

are published that provide square foot and other unit costs for a variety of

buildings.

FINAL ESTIMATE TYPES:

Final detailed estimates can be prepared when the design and contract

documents have been completed, or are essentially complete. Generally two

types of final estimates are prepared; one by the contractor intending to bid

the project, and the other for the owner's use in preparing budgets and

evaluating bids for the project. The estimate prepared for the owner is called

the Engineer's Estimate when the owner is a public agency, and is almost

always required for bid comparisons. The owner's estimate is optional for

privately funded projects. The major difference between a contractor's bid

estimate and an engineer's estimate lies in the information the two estimators

have at their disposal. The Estimator contact or contractor’s estimator normally

has much more detailed information at his disposal. The engineer's estimator is

forced to rely on more general information, since he does not know which

contractor will receive the award and construct the project.

In either case, the final estimate must be as accurate as possible, since it

represents the money that will be received or spent when the project is

actually constructed.

FACTORS INFLUENCING (OR TO BE CONSIDERED) SPECIAFICATION & METHOD?

The major factor which is influencing the specification is as follows

designers:

– structure by discipline, e.g. acoustics, fire, lighting

– structure parallel to Approved Documents

• building control officers:

– structure parallel to Approved Documents

– limit to statutory scope, e.g. not aesthetics

• estimators & tenderers:

– two-part structure: separate standard content from project

variables, e.g. NBS Domestic

– elemental structure: cost data is elemental, e.g. BCIS

• contractors:

– disassembly: compliance, subcontracting

– compliance: separate tests, inspections, samples

– subcontracting: hence work sections, small sections

– mark up: wide margins

• subcontractors:

– on-site: simple English, simple structure

– separate products & execution

– general technical requirements

• contract administrators:

– dealing with compliance (see slide 11)

• courts:

– don’t blur obligations

– don’t address those outside the contract

– consider precedence

• facility managers

– record specification – 100% brands

– locational structure

– specifications often cover O&M manuals, H&S files, spares etc

• project managers:

– specification is key to quality management

– communications nexus

FACTORS INFLUENCING RATE ANALYSIS?

Rate analysis is the study of principal role played by various constituents,

elements of construction such as equipment, cost of labor, number of

equipment etc.

Factors affecting rate of an item :

• Locality and situation.

• Size and extent of work.

• Nature of project.

• Height/Level of work at which it is being executed.

• Environmental and climatic conditions.

Size:

The smaller the project in terms of scope or the number of square feet, the

more it will cost per square foot. Contractors have a set of basic “start-up

costs.” These start up costs remain about the same in real dollars for every

project. Thus for a very large and expensiove project, the start up costs will be

a small percentage of the total construction cost. For a small project, since

start-up costs remain stable, they will constitute a large percentage of the total

construction budget. If the cost of start up for any project is $4,500.00, and the

total cost of the project is $450,000.00, the total start-up costs are 1%. However,

if the total project cost is $30,000.00 then the start-up is 15% of the total cost.

Start-up becomes a major cost factor when estimating construction costs for

small to medium sized projects.

Special Construction:

Complexity can greatly increase the cost of the project. These conditions

may include renovations, heavy loading, i.e. large quantities of files or a library,

hazardous materials, etc. Renovation, especially if it requires altering or moving

structural components, can be costly because it necessitates demolition as

well as building. Quantities of files and books are heavy so the flooring may

require additional structural support. Special construction may also be

necessary to shield surrounding spaces from noise, fire and other hazards.

Project accessibility:

Sites may be difficult to access, either geographically or because the

space is used during business hours, requiring that the project be scheduled for

off hours. This can be a problem when adjacent spaces have sensitive

equipment, or when construction materials containing hazardous chemicals

are used in the construction process. (You will be surprised how many

construction materials do in fact contain hazardous chemicals. This presents a

unique problem which has yet to be adequately addressed, because even if

the area under renovation can be physically isolated from other areas of the

building, very often the HVAC system has not been readjusted, and these

chemicals are often circulated throughout the area or building, creating

hazards for occupants. This situation is especially critical in permanently

enclosed office buildings (those whose windows are non-operating, i.e. they

don’t open) since chemicals can linger for long periods of time. The most

frequent culprits in terms of hazardous chemicals are glues, paint removers,

mastics, carpet backings, and synthetically produced building materials. Be

alert for these chemicals: toulene, xylene, formaldehyde, mineral spirits,

naphtha, and other kinds of organic solvents. In summary, these factors can

increase the time and effort needed by the contractor and result in an

increased cost of construction:

isolating areas under renovation

providing physical access to move materials, equipment, and

construction personnel to the site

Ensuring periods of work when construction will not disrupt the on-going

operation of the company

Project Difficulty:

Other factors can also raise costs: The project schedule may be tight, e.g.

the client’s current lease is expiring and the work must be completed by a

specified date so that the client can move in to their new space. Sub-

contractors may have to work over time or neglect other projects in order to

finish work on time. This will raise the contractors price for the work because

many people will need to devote more hours in a short period of time to the

work, increasing the stress on workers, removing them from other projects on

which the contractor is working, making coordination of trades more difficult,

and finally presenting the possibility of needing to pay ‘time and a half’ to

union laborers (which most construction trades are in many states).

Level of detail may also make the project more difficult and costly.

Time of Year

Building construction is a seasonal enterprise. There are periods of the

year when contractors are busy and can barely keep up and then there are

periods of the year when they are likely to be looking for work. From early

January to late February or early March, General Contractors will be seeking

work to fill their schedule for the following construction season (approximately

early April through late October or early November). During this time you are

more likely to get a more competitive bid for a project. After this period it is

likely that bids will be higher or the contractors who are available will be the

less qualified and were not hired for other projects.

Labor Rates

The general state of the economy will affect the cost of a project so it is

important to watch what is happening with the rate of inflation in developing

accurate construction estimates. When the economy is booming (like it is now)

and the unemployment rate is very low, there may be some wage pressure,

particularly in the skilled and labor intensive construction industry. If there are

indications of inflationary pressures, you must place some limits on your

construction estimate. You should either indicate to the client that the period

for which such an estimate is accurate will be relatively brief, or include some

budgetary contingency for inflation over the period before bids are ‘let’ and

the project is awarded to a contractor.

Material Costs

The type and availability of a particular material can also affect your

approach to a cost estimate. If your client insists upon a particular material or if

a particular manufacturer’s product is crucial to the success of a project, the

cost of that specific item can drive up the cost of the project. This is essentially

a closed specification. If, however you can accept a material of equal or

somewhat reduced quality, you will leave room for greater price competition

and lower the project cost. (Incidentally, the availability of a product or

material can also affect the success of a project relative to the client schedule

expectations. When you are selecting products or materials, you should also

consider the concerns of “lead time” (the time it will take for an order to be

manufactured and delivered).

METHODS OF VALUATION?

Valuation of a building depends on the type of the building, its structure

and durability, on the situation, size, shape, frontage, width of roadways, the

quality of materials used in the construction and present day prices of

materials. Valuation also depends on the height of the building, height of the

plinth, thickness of the wall, nature of the floor, roof, doors, windows etc.

The valuation of a building is determined on working out its cost of

construction at present day rate and allowing a suitable depreciation.

Six Methods of Valuation

1. Rental Method of Valuation

2. Direct Comparisons of the capital value

3. Valuation based on the profit

4. Valuation based on the cost

5. Development method of Valuation

6. Depreciation method of Valuation

Rental Method of Valuation

In this method, the net income by way of rent is found out by deducting

all outgoing from the gross rent. A suitable rate of interest as prevailing in the

market is assumed and Year’s purchase is calculated. This net income

multiplied by Year’s Purchase gives the capitalized value or valuation of the

property. This method is applicable only when the rent is known or probable

rent is determined by enquiries.

Direct comparison with the capital Value

This method may be adopted when the rental value is not available from

the property concerned, but there are evidences of sale price of properties as

a whole. In such cases, the capitalized value of the property is fixed by direct

comparison with capitalized value of similar property in the locality.

Valuation based on profit

This method of Valuation is suitable for buildings like hotels, cinemas,

theatres etc for which the capitalized value depends on the profit. In such

cases, the net income is worked out after deducting gross income; all possible

working expense, outgoings, interest on the capital invested etc. The net profit

is multiplied by Year’s Purchase to get the capitalized value. In such cases, the

valuation may work out to be high in comparison with the cost of construction.

Valuation based on cost

In this method, the actual cost incurred in constructing the building or in

possessing the property is taken as basis to determine the value of property. In

such cases, necessary depreciation should be allowed and the points of

obsolescence should also be considered.

Development Method of Valuation

This method of Valuation is used for the properties which are in the

underdeveloped stage or partly developed and partly underdeveloped stage.

If a large place of land is required to be divided into plots after providing for

roads, parks etc., this method of valuation is to be adopted. In such cases, the

probable selling price of the divided plots, the area required for roads, parks

etc. and other expenditures for development should be known.

If a building is required to be renovated by making additional changes,

alterations or improvements, the development method of Valuation may be

used.

Depreciation Method of Valuation

According to this method of Valuation, the building should be divided

into four parts:

1. Walls

2. Roofs

3. Floors

4. Doors and Windows

And the cost of each part should first be worked out on the present day

rates by detailed measurements.