Thursday, October 25, 2007
Types of Estimates:
There are several kinds of estimating techniques; these can be grouped into two main categories
1. Approximate estimates
2. Detailed estimates
1. Approximate Estimates
An approximate estimate is an approximate or rough estimate prepared to obtain an approximate cost in a short time. For certain purposes the use of such methods is justified.
2. Detailed Estimate
A detailed estimate of the cost of a project is prepared by determining the quantities and costs of every thing that a contractor is required to provide and do for the satisfactory completion of the work. It is the best and most reliable form of estimate. A detailed estimate may be prepared in the following two ways
(a). Unit quantity method.
(b). Total quantity method.
(a) Unit Quantity Method
In the unit quantity method, the work is divided into as many operations or items as are required. A unit of measurement is decided. The total quantity of work under each item is taken out in the proper unit of measurement. The total cost per unit quantity of each item is analyzed and worked out. Then the total cost for the item is found by multiplying the cost per unit quantity by the number of units. For example, while estimating the cost of a building work, the quantity of brickwork in the building would be measured in cubic meters. The total cost (which includes cost of materials. labour, plant, overheads and profit) per cubic meter of brickwork would be found and then this unit cost multiplied by the number of cubic meters of brickwork in the building would give the estimated cost of brickwork. This method has the advantage that the unit costs on various jobs can be readily compared and that the total estimate can easily be corrected for variations in quantities.
(b) Total Quantity Method
In the total quantity method, an item of work is divided into the following five subdivisions:
(I) Materials
(II) Labour
(III) Plant/Machinery
(IV) Sundries & Contingencies
(V) Overheads & Profit.
The total quantities of each kind or class of material or labour are found and multiplied by their individual unit cost. Similarly, the cost of plant, overhead expenses and profit are determined. The costs of all the five sub-heads are summed up to give the estimated cost of the item of work. For example, the cost of brickwork in a building would be determined as below:
I ( i ) Cost of Materials at the source Rs. xxxxx
Bricks Rs. xxxxx
Sand Rs. xxxxx
Cement Rs. xxxxx
Water & Electricity Rs. xxxxx
(ii) Cost of Handling and transporting above materials Rs. xxxxx
II Cost of Labour, both skilled and unskilled Rs. xxxxx
III Cost of plant/machinery Rs. xxxxx
IV Sundries & Contingencies Rs. xxxxx
V Overhead & Profit Rs. xxxxx
Total Cost of Brickwork Rs. xxxxx
Data Required for Preparing an Estimate
In order to prepare a detailed estimate the estimator must have with him the following data:
1. Plans, sections and other relevant details of the work.
2. Specifications indicating the exact nature and class of materials to be used.
3. The rates at which the different items of work are carried out.
To enable an estimator to take out the quantities accurately, the drawings must themselves be clear, true to the fact and scale, complete, and fully dimensioned. The estimator has also to bear in mind certain principles of taking out quantities.
Steps in Preparation of an Estimate:
There are three clearly defined steps in the preparation of an estimate.
1 . Taking out quantities
In the first step of taking out quantities, the measurements are taken off from the drawings and entered on measurement sheet or dimension paper. The measurements to be taken out would depend upon the unit of measurement. For example, in the case of stone masonry in superstructure, length, thickness and height of the walls above plinth level would be taken out from the drawings and entered on the measurement sheet, whereas, in the case of plastering only the lengths and heights of the walls would be entered. Obviously, the unit of measurement in the first case is cubic meter and that in the second case is square meter
2. Squaring out
The second step consists of working out volumes, areas, etc. and casting up their total in recognized units.
3. Abstracting
In the third step all the items along with the net results obtained in the second step are transferred from measurement sheets to specially ruled sheets having rate column ready for pricing. The second and third steps above are known as working up. All calculations in these stages and every entry transferred should be checked by another person to ensure that no mathematical or copying error occurs. An estimating/ documentation software will be handy while doing these type of work.
Qualifications of an Estimator
A good estimator should possess the following quantifications:
1. A thorough understanding of architectural drawings.
2. A sound knowledge of building materials, construction methods and customs prevailing in the trade.
3. A fund of information collected or gained through experience in construction work, relating to materials required with a clear understanding of its alternatives and substitutes, hourly output of workers and plant, overhead expenses and costs of all kinds.
4. An understanding of a good method of preparing an estimate.
5. A systematic and orderly mind.
6. Ability to do careful and accurate calculations.
7.Ability to collect, classify and evaluate data that would be useful in estimating.
Thus an estimator should always be alert in preparing estimates as he has to choose from a vast ocean of data. Collecting, classifying, evaluating and presenting it in a systematic way is not a simple task. Effective use of a tool, such as a software, can bring him a lot of ease and accuracy in his endeavor.
Labels: bill of quantity software, Construction estimating Software, estimator, preparing estimates, rate analysis
Wednesday, October 3, 2007
An estimate is a well quantified and time bound list of resources used for the successful completion of a project. The very first step in planning a project is to estimate the resources involved in completing the Project. Care should be taken while preparing the estimate for it should have a close approximation of figures against their actuals. Whether or not the estimate actually agrees with the actual cost will depend upon the expertise and quality of tools used for estimating construction costs.
Deciding the budget of the construction and trying to keep it within the limits is one of the difficulties faced in the construction business. There are many problems that crop up during the actual process of construction for which allowances have to be made.
Four areas of Estimating
While the broad definition of estimating is to give a closely accurate idea of what a project is going to cost, it can actually be broken down into four different points. It is important that the estimate is very detailed and accurate, and this requires using four different areas. The four things that are very important to consider when doing constructing estimating in building include materials, labor, plant, and time.
Estimating Residential Construction
When it comes to estimating residential construction costs, most small and medium construction contractors find themselves in a state of flux. They work hard on collecting and collating data, but end up with little or no profits. To top it, they are operating in a fiercely competitive industry that's in the middle of a slump. To convert his estimates into actual sales invoices, a construction contractor has to be on the ball while estimating a residential construction project and here is a small primer on how a contractor must build his estimate.1. Location and environmental costsBefore beginning to work on the actual construction, a contractor should survey the residential plot upon which the building will be constructed. There may come up some building constraints due to various factors, such as the location of the construction site and even environmental factors, e.g., the land being located in a "wetland" kind of area. Other times, a contractor may be asked to clear the site by demolishing an existing structure. These factors add to the construction cost. It is, therefore, important that a contractor be thorough with his research so that these additional costs can be built into the residential construction estimate.2. Construction costsNormally, a contractor is given a house design and asked to give an estimate of the construction cost based on material costs and labor costs. While giving a residential construction estimate, a contractor must break up his quotation into:
a. Foundation: Foundation cost comprises of the cost of concrete used in laying the foundation of the house as well as in footings, walls, slabs and columns, plus the expenditure on the machinery used.
b. Framing and walls: This includes the cost of wood used in the building – paneling of walls, floors and ceilings consumes a lot of wood. Apart from wood, these structures also consume a whole lot of metal, brick, stone, laterite and so on.
c. Roofing: The cost of the roof, whether it is concrete or a combination of truss assembly and metal sheets/ tiles.
d. Flooring: Flooring cost includes costs related to any item used for covering the floor of a home – such as vinyl, tiles, carpet and even sub-flooring material such as carpet pads.
e. Exteriors: This includes the cost of the material required to do the exterior of a home, be it bricks, stones or a combination of these.
f. Interiors: Any material required to bring the inside of a home to a finished state should be included in the estimate, for example, kitchen cabinets, bedroom cabinets, wall paints, or anything extra desired by the client.
g. Doors and Windows: Doors and Windows consume wood, glass and small hardware sundries that must all be factored into the estimate.
h. Electric work: The cost of electrical work includes the costs for wiring, outlet points, lighting fixtures and connections from the main power supply.
i. Plumbing: This includes the cost for preliminary works such as connection to sewage lines and connections from water lines, and the cost of plumbing fixtures for the bathrooms, kitchen and utility room.
j. Appliances: A contractor is expected to finish a home with certain appliances such as fire safety gadgets, anti burglary gadgets, and a garbage disposal facility, so he should build these costs into his estimate. If any other appliances are needed, they can be added on.
k. Heating/Cooling: Central air conditioning costs, ductwork and other heating/cooling costs.Accommodating all the factors that contribute to the total cost is not a precise exercise. There are bound to be ups and downs because a contractor relies on too many variable factors. Therefore, it is prudent that the contractor builds in a contingency reserve, an escalation clause and a market condition allowance into his estimate. A contractor must also be careful if he is outsourcing any of the construction services – and he must insist on written commitments and penalty clauses with his suppliers.Other costs a contractor must be wary of:Normally, a small or a medium construction contractor will plug in the usual construction costs into his estimates. He must also take care to ask the client if he is expected to perform any or all of the following services:
1. Getting the site ready for construction.
Once the contractor has factored in all the visible and invisible costs, he must begin estimating the residential construction costs, add his margin and hope that the client accepts his estimate. Since a contractor has a whole lot of things to do and manage before and during construction, it will do him a world of good if he relies on an efficient software that gets everything organised and helps to get things done on time. A good construction estimation software will help him strategise and execute his plans without a hitch, without any hiccups in the schedule. Moreover, his estimation on construction costs will be accurate and fluctuations, if any, will be controlled and ironed out with a fool proof estimation software which in turn will give the contractor a solid grip on his business.
Labels: bill of quantity software, Construction estimating Software, cost analysis, estimates, estimating buildings, preparing estimates, quantity estimating, rate analysis
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