**What Is Estimate?**

An **estimate** is a technique to calculate the **quantities **of various **items of work**, and the **expenditure **likely to be **incurred thereon**.

The total of these **approximate** expenses to be **incurred **on the work is known as the **estimated cost **of the work. The approximate **cost **of a **work **is a close **approximation** of its **actual cost**.

There are 12 **Types of Estimate**s **in civil engineering** Approximate or Rough **Estimate**, Plinth Area Estimate, **Service Unit Method**, Floor Area Method, Carpet Area Method, **Typical Bay Method,** and **Cost Comparison Method**.

**What is Estimation?**

**Estimation** is the **technique **of estimating the **various quantities** of work and the **expected expenses **to be incurred on a **particular **work or project to **execute**.

In case the **funds **available are less than the **estimated cost **the work is **executed **in part or by **reducing **it or **specifications **are altered.

**Estimation **gives an **approximate **idea of the time required for the **completion **of the work. The **estimate **is required to invite the **tender **and **quotations **and to **arrange **a contract.

The **estimate **is also essential to control the **expenditure** during the **execution **of work. An estimate **decides **whether the **proposed **plan matches the **funds **and budget **available **or not.

The rate used in the **estimate **should check with the **current standard **schedule of rates (SOR) & in the case of **quantity**, it should check with the **standard data book**.

**Read More:** **Types Of Cost Estimates In Project Management**

**Types of Estimates**

**The followings are Types of Estimates in Construction**

### 1. **Preliminary or Approximate or Rough Types of Estimates**

This **type of estimate** is also called the** **budget**, a preliminary estimate**. This **preliminary** estimate is prepared in the** initial stage of the project** to give a clear idea to the client about the **funds **needed for the project and to **get approval** from necessary **sanctioning bodie**s (for example: to get loans from banks).

**Documents** like project **drawing plans**, details about the land including **electricity & water supply system** and **sanitary system** a full clear **report **are necessary for the previous experience.

Eg: To **calculate **the estimate for a **house**, a **previously completed** similar house will be considered.

Here the **estimator **already **knows **the rate for **1m2 areas** & with that he/she calculates the **cost** **estimate **for the **newly proposed **area of a **similar house**.

**Approximate estimate = Rate of 1m2 area(already known value) x Proposed area (m2)**

**The preliminary estimate may be prepared in various ways for different work and structures as:**

**A) For Building:**

**Service unit method****Plinth area method****Floor area method****Carpet area method****Cubical content method****Typical bay method****Approximate quantity method**

**B) For Road and Highways:**

For **roads** and **highways**, it is calculated per **kilometer **basis depending on the **nature **of the **road**, width, thickness of **metalling**, etc.

**For 10 km of a state highway,** the **approximate cost is Rs.6,00,000/- per km.**

Total Cost = 10 x 6,00,000

= 60,00,000 Rs. = **Rs. 60 lakh**

**C) For Irrigation Canals:**

**The cost of the Irrigation canal is calculated per kilometer basis depending on the capacity of the channel.**

The **approximate cost **of a 10 km length of **irrigation channel **of** 3 cubic** meters per sec **capacity **@ Rs. 1,00,00 per km.

Total cost = 10 x 1,00,00 =10,00,00 Rs =** Rs. 10 lakh.**

**C) For Bridge:**

The **cost** of the bridge is calculated per **running meter **of span depending on the roadway, nature, **depth of** **foundation**, **types of structure**, etc.

**The approximate** cost of a bridge o 4 spans of 50 m each span @ Rs. 50,000 per **running meter **of the span is

Total cost = (4×50) x 50,000

= 1,00,00,000 =** Rs. 1 crore**

**E) Water Supply and Sewerage Project:**

**It cost is calculated per head of population served.**

**Approximate cost **of water supply for a **population **of 80,000 @ Rs. 100 per head **comes **to 80,000 x 100 = 96 lakhs.

**F) Over Head Water Tank:**

Its cost is **calculated **on basis of the **capacity **per liter of the tank **depending **on the type of structure, the **height **of the tank, etc.

**Approximate cost **of an overhead **RCC tank **of 1 lakh liter capacity @ Rs. 3 per liter works out to be 1,00,000 liter x 3 = **Rs. 3 lakhs**.

### 2. Plinth Area Estimates

In this **type of estimate,** the plinth is found by multiplying the values of the **length **of the plinth, the **width** of the plinth, and the **plinth area rate. **

Here the **plinth area** is referred to as the **external plinth area **of the building at **floor level**. **Simply **it can be also stated as the **roof**–**covered area **of the **building**.

The **plinth area rate** is derived by dividing the** total cost of a previously constructed building** by the **plinth area method**.

**Documents **such as a line **plan **with complete **specifications **& costs for services such as **water**, and **electricity **should be **attached **with the plinth area **estimate**.

**Plinth area estimate = Plinth area x Plinth area rate**

**Plinth area = Plinth length x Plinth width**

**Plinth area rate = Total cost of a previously built building / Total plinth area of the building.**

In this **method **cost of a **1 m3 area** is calculated from the cost of similar **plinth area **construction in the **nearby **area which is **known **as the **plinth area** rate.

**Estimate cost = Plinth area x plinth area rate for 1 m2 area**

**For Example,**

**A building has a plinth area of 200 m2 and the plinth area rate in this area s Rs. 3500/- per m2.**

**Estimated cost = 200 x 3500 = 7,00,000 Rs**

There are some **restrictions **in calculating the plinth area of a **building project **and some areas have to **include **or exclude when **calculating **the **cost**.

Among that, **areas **include are, a **floor area **with an area of walls at floor level **excluding **the offsets of the building, **internal **shafts of sanitary **fittings **within 2m2, lifts,** air conditioning ducts**, an area of the **porch **at floor level, a room on the **terrace **or rooftop with verandah **outside**.

Areas that can’t include are an **area **of lofts, **open balconies**/**un**–**enclosed balconies**, and fascia, **towers **that project above **terrace **level, louvers & **vertical **sun breakers.

**Read More:** **Building Estimation Excel Sheet Free Download**

**3. Service Unit Method**

In the **Service Unit Method, **the Service Unit **indicates** the most **important unit **in a structure. The entire **structure **is divided into a **number **of service units.

For example, in a **school building**, the service unit is in the **classroom**. Then,** **the **approximate cost of structure = Number of service units in the structure x cost of service units** in a** similar existing structure.**

The **approximate estimate **of the **school building** is **prepared **on the basis of the **service **unit and the service unit for the **school building **is the **classroom.**

**The service units for various structures are given in the below table.**

Sr. No. | Types of Construction | Service unit |

1. | School, Collage | Classroom |

2. | Hospitals | Bed |

3. | Hostel | Students |

4. | Hotel | Room |

5. | Theatre(Cinema) | Seat |

6. | Stadium | Seat |

7. | Jail | Kotani |

8. | Stable | Animal |

9. | Water Tank | Litre |

10. | Dam | Hectare Meter |

11. | Water Supply Scheme | Person |

12. | Road | Kilometer |

13. | Canal | Kilometer |

14. | Bridge | Meter |

15. | Power Station | Kilowatt |

**Types of Construction and Their Service Unit (Service Unit Method)**

**While Deciding on a service unit of similar construction the following points should be noted.**

**1) Change in cost of land**

**2) Change in the price level of different materials.**

**3) Change in rate of labor.**

**4) Change in the specification of construction.**

**This type of estimate is generally used in places where units are easily defined. **

**4. Floor Area Method**

**The floor area is calculated by deducting the area of the wall from the plinth area.**

**Floor area = Plinth area – Area of wall**

In the **calculation **of the area of walls, the **thickness **of the wall shall be **inclusive **of finishes and dado if the **height **of such finish is more than **1 m from the floor finish**.

**The following points must be included in the wall area:**

i) **Door area another opening in the wall.**

**ii) Built-in cupboard, almirah, etc. appearing within a height of 2.2 m from the floor.**

**iii) Flues that are within the wall.**

**Example,**

**Estimate cost = Floor area x Floor area rate**

Let, one **building **gas floor area** of 100 m2, **and the floor area rate is** 4000 Rs.**

**Estimated Cost = 100 x 4000 = 4,00,000 Rs.**

**5. Carpet Area Method**

**The carpet area is the floor area less the area of the followings portions (as per IS 3861)**

**Verandah****Corridor, Passage****Entrance hall and Porch****Staircase****Bathroom and W.C.****Kitchen and Pantry****Store, Machine Room for lift****Shaft for sanitary pipes etc.**

**Estimated Cost = Plinth area x plinth area rate**

**6. Typical Bay Method**

This **method** is useful in the case of a **building** that has several **similar bays**. A bay is a space from the center to the **center **of two successive **columns**. A typical interior bay is **selected **and its total cost is **worked **out. Then,

**Approximate cost of proposed building = numbers of bays x cost of one bay**

**The following points are to be noted:**

**Necessary**corrections should be**made**for end bays due to**end walls**.- Sufficient
**allowance**should be made to**compensate**for the**small things**that are overlooked.

**7. Cost Comparison Method**

This method is suitable for the **estimate of the prototype structure**. For example when prototype **staff quarters or railway stations** etc, are required to be **estimated **approximately then the **estimate **for such **prototype **work is prepared by **comparing **the **previous cost **with the **present market rates, **normally by **increasing **the past cost on a **percentage basis**.

Such an **estimate **can be prepared in a **short time even during meetings also**. But expert knowledge is necessary to **estimate **the present cost of **construction **as compared to previously **recorded costs**.

**Read More:** **Valuation Of Building And Methods Of Valuation Of Property**

**8. Cubic Content Method**

In this method **estimate **is done by multiplying the **volume **of the unit cubic rate **achieved **from the **previously **(also recent) estimate.

The cubic** Content Method** is a little bit **more **accurate than the above-**mentioned **methods and **mostly **suitable for **multi-storied buildings. **

The **price **of corbelling (**corbel**-a piece of broken stone, **wood**, brick, or any **building material**, **projecting **from the face of a wall and **generally **used to **support **a cornice or arch, etc), cornice, and other works like that are **neglected**.

**Cubic content estimate = Volume of the building or structure x Unit cubic rate (original value)**

**The volume of the building = Plinth area (length x breadth of the proposed building) x Height of the**

building (floor to rooftop)

**Unit cubic rate = Total cost of the previously constructed building / Total volume of that building**

**9. Annual Repair Estimate or Special Repair Estimate**

It is used for a**nnual repair estimates or special repair estimates. **These estimates are **prepared **for the purpose to **maintain **the constructed element in **good condition**.

Works that **included **when considering **repair works, whitewashing, painting, plastering works, patching works, sanitary works, etc. **

A **special repair estimate** is prepared in a **situation **where the **costs of materials increased** when compared to the **annual **repair estimate **cost**.

**10. Revised Estimates**

**A revised estimate** is prepared when the cost of the **previously **submitted estimate **increases by 5-7% **or more than that.

But here the** reason for calculating the estimate **must have a **strong & valid reason** like a sudden **increase **in the cost and expenses of **materials**.

The **reason **and comparative **statement **between the two **estimates **should be annexed with a **revised estimate**.

**11. Supplementary Estimate**

This type of **estimate **is **prepared **when there is a necessary** situation for supplementary works**, to progress out the **original work**.

The **annexure **of the originally **prepared estimate **and supplementary amount of the **originally **prepared **estimate **when submitting for **requesting approval**.

**12. Detailed Estimate**

** **It is the most important **type of estimate** for building **construction**. A detailed estimate is **prepared** with the help of a **complete **set of contract **documents**.

The **preparations **of the detailed **estimate **can do under 2 phases such as **working **out quantities of **different **works and **calculating **the cost of **each **work.

**a) Work out with quantities of different work**:

- The
**whole construction**work procedure is**divided**into**categories**such as excavation and earthwork,**concrete work**, formwork, reinforcement,**masonry work**, roof covering and roof**plumbing**, carpentry, painting and**decorating**, plumbing, electrical**installation**, etc. - Decoration of the
**approximate estimate**depends upon the area to be**decorated**. - The
**measurement**-taking procedure is done with the help of**drawings**/**plans**and then they are entered into the**measurement**. - A measurement is a form that contains a
**number of columns**to enter the**respective measurements**and descriptions of the**works**. Finally, the measurement**columns**are**multiplied**to get the necessary**quantity**.

**b) Calculation of the cost of each work**:

- The
**already**obtained quantities are**used**to get the cost of**each work**. Estimated costs of each work item are**summarized**in ascending order and that**document**is called the**Abstract sheet**. **Detailed types of estimates**should include all the**related**documents such as**reports**,**specifications**, drawings & plans, design**charts**, and**schedule of rates(SOR)**.- There are
**various factors**that affect the**cost**of each work such as**material quantity**,**transportation**of materials,**location**of the site,**labor charges**, cost of**equipment**(commonly allowed 2% of the estimated cost),**overhead**charges (commonly allowed 2.5% of the estimated cost),**contingencies**and unforeseen (commonly allowed 4-5% of the estimated cost)**items**are needed to**consider**well while**preparing**the**detailed estimate**.**(Types of Estimates in construction)**

## FAQs:

### Types of Estimation

**The following are 12 Types of Estimates used in construction,**1. Preliminary or Approximate or Rough Estimate

2. Plinth Area Estimate

3. Service Unit Method

4. Floor Area Method

5. Carpet Area Method

6. Typical Bay Method

7. Cost Comparison Method

8. Cubic Content Method

9. Annual Repair Estimate or Special Repair Estimate

10. Revised Estimate

11. Supplementary Estimate

12. Detailed Estimate.

### What is Estimation in Civil Engineering?

**Estimation** is the technique of estimating the various quantities of work and the expected expenses to be incurred on a particular work or project to execute.

### Plinth Area Estimate

**Plinth area estimate is a method of approximate estimate in which the **plinth area is multiplied by the **plinth area rate to find out the **approximate cost of construction.

### Methods of Estimation in Civil Engineering

**12 Types of Cost Estimation in Construction**,

1. Preliminary or Approximate or Rough Estimate

2. Plinth Area Estimate

3. Service Unit Method

4. Floor Area Method

5. Carpet Area Method

6. Typical Bay Method

7. Cost Comparison Method

8. Cubic Content Method

9. Annual Repair Estimate or Special Repair Estimate

10. Revised Estimate

11. Supplementary Estimate

12. Detailed Estimate.

### Estimation of Building

**It** is the technique of e**stimating the various quantities of work** and the expected expenses to be incurred on a particular work or **project to execute. Estimation** gives an** approximate idea **of the time required for the **completion of the work.** The estimate is required to invite the tender and **quotations and to arrange a contract.**

**Watch Video:** **Building Estimation With 3D Model**

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dhavalbhai saniawalaVery use full for civil engineering students

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Bharat Singh RawatIt is useful not only for students but employed persons also. Thank you very much for writing. God Bless you, sir.