In this Blog, our expert Mr Chetan Sharma from Civil Guruji brings to you an introduction about building estimation and budgeting where you will learn about estimate of a project, completely, from site cleaning till the handover.
The process of calculation of “quantities” and “cost” of various items in connection with the construction project is called estimation. It’s what where we calculate quantity and cost of item related to a building construction. There two more important thing related to estimation, these are SOR and BOQ.
SOR - Schedule of rates & BOQ Bill of Quantity
SOR is the schedule of rates. After working out the quantities we go to SOR. Here we get the rate of items whose quantities have been listed previously. Each item has some rate, which are quoted in SOR. Multiplying quantity of item with rates gives us amount in rupees, the final value, the budget, a prediction of cost before construction of a building. This amount is called BOQ of a project, bill of quantity.
We’ll learn through this module how to arrive at BOQ. We know what all to do for this.
We’ll look at Three things in calculations
Let’s see few Important Calculations
1. Volume calculation - for 3D object we find out volume to evaluate it. Volume used when we have 3 dimensions and its unit is cu m, ex all concrete and brickwork item.
2. Area calculation - for all 2D objects we find out area. There are 2 ways for it either by L*B (plasters, slab) or L*H (wall, plastering), unit is sq m.
3. Enumerative quantity - these are the quantities that are countable, they are found out as no. per piece. Unit of measurement is “each”.
4. Running metre – suppose we have a plumbing pipe of diameter 25 mm. Its measurement from end to other is what we call as length. Since we have here only one dimension so its unit of measurement is m.
5. Mass - we have a simple calculation for mass, the one we know since school
Density=mass / volume
Mass=density X volumeAll metal related items are used in a building like steel, copper, aluminium, brass are measured in terms of mass, kg. We must know their density and volume for this
To begin with we first of all need to know what is exactly estimation ?
To understand this properly lets come out from construction industry and take up some simple instance of our day to day life,
Say arranging a home party or a vacation trip.
For any such event what the first thing we look in for?
Its budget i.e. how much cost will be incurred there. Similarly for a trip, we see basically two things- first duration and second the budget.
If you are to organize a trip to Manali but if you never been to Manali then you cannot work out its estimate. You will need some localite of that place or you can even search in Google.
You can call out any of your friend and ask him who has visited there.
He may suggest you to have taxi the preliminarily requirement to reach airport or to go from there to some hotel. Taxi will become the first item of our trip, taking 30 min of time and costing Rs 200.
Then it would be a flight for 2hrs and 4000 fair as we don’t have a direct connectivity and one has to go via Chandigarh. Hence a cab would be the third item, charging Rs 1200 form 6 hrs.
If we note down all these in a diary we will have here 3 columns,
One each for item duration and cost. These are the items included for a trip to Manali.
We will also have a charge for logging in hotel for a day and visit to some tourist spot charging Rs 2000 and 1500 respectively.
For returning again we would need a cab flight and taxi. Adding all the values of 2nd column will give us the total duration and of 3rd column the total cost, the budget. For making an estimate knowledge about each and every item is very necessary. We lack there and that’s why we are unable to estimate of the construction project because there we don’t have an idea about items needed for a building construction. We don’t know about construction process, steps involved from beginning till the end. In building estimation a nos. of quantities are involved. In above example, the estimate we had in was for a single person but if there are 3 persons going together then the quantity of each individual item will get multiply and so we will have one more column for the no. of items along with cost and duration. Let’s look at the technical definition. What we saw above was a practical interpretation of it, estimation in part of our day to day life. All mothers in home do this daily while cooking.
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