留學生會計學專業畢業dissertation范文：The Cost of Buil
The Cost of Buildings
Contents List
1. Introduction
2.留學生dissertation網 The bidding process
3. Design costs
4. Construction costs
4.1 The Groundwork and Foundations
4.2 External works
4.3 Landscaping
4.4 Costs of mechanical and electrical work
4.5 Alterations and repairs
5. Cost of the construction Equipment
6. Material costs
6.1 Concrete
6.2 Masonry
6.3 Wood
6.4 Doors and Windows
6.5 Metals
7. Labor costs
8. Insurance
9. Professional fees
10. Other consequences costs
11. Conclusion
12. Reference
Chapter 1
INTRODUTION
There are two systems that establish standards for the building design/ construction estimating process. One system, Master Format, is oriented to materials and installation. The other system, Uniformat, analyzes and compares various casts.
Building cost estimates classification. Related to various types of building cost estimate, a prudent owner or contractor must associate the “expect accuracy range”. The project total cost is greater than engineering and construction costs because items such as land acquisition, market study, environmental studies, and financing costs are also included. A critical element for controlling the cost, schedule, and scope of a project is gaining and maintaining control of the design process. Failure to control and http://www.mythingswp7.com/dissertation_writing/Accounting/manage this process will result in delays and increased construction costs. (Calin, M 2003)
The building industry and the civil engineering industry together are often referred to as the construction industry, and many firms operate in both sectors, even though their staff and organizations may be largely separate. The UK construction industry is quite large, with a turnover in 1987 of 34 billion pounds. This represented nearly half 留學生dissertation網 of the country’s fixed capital formation and about 8% of the gross national product. (Douglas, J and Peter, S 1991)
It is therefore very important for the cost planner to look at the general economic situation when forecasting costs. (Douglas, J and Peter, S 1991)
There are two ways in which building costs can be estimated or analyzed, based in the first instance on the prices charged for the finished buildings or parts thereof, and in the second instance on the cost of the resources required to create them.
Cost planning as a process is difficult to define concisely as it involves a variety of procedures and techniques used concurrently by the quantity surveyor (QS) or building economist. Traditional cost planning will usually follow the conventional outline design, detailed design process. In a practical sense, the cost planning process stars with the development of a ballpark figure to allow the client to decide whether the project is feasible. (Richard, K 2007)#p#分頁標題#e#
Public buildings are assets needed to serve government purposes. The public is called upon to invest in these assets and pay the costs of their upkeep. Minimizing the total costs of ownership 1 is the most efficient use of the public's resources to obtain the services these assets provide. Overcoming the economic, technical, and political obstacles to meaningful control of the total costs of public buildings will enhance productivity and the public's return on its investment. Agencies' managers generally recognize the need for facilities that serve efficiently the purposes of government and seek ways to overcome obstacles to effective cost management.
The sponsors of the Federal Construction Council (FCC) 2 asked the Building Research Board (BRB) to undertake a study of the use of life-cycle cost analysis a formal set of principles and procedures for considering total costs of ownership for setting building design criteria. This document is the final report of that study. (National Research Council Staff, 1991)
Chapter 2
THE BIDDING PROCESS
Bidding can be considered as one of the most important processes in a whole building project and contractor’s operations. In order to get the work, the company contractor has to be successful at bidding for the project. The higher bidding means the more profits, but it leads to the less opportunity to get the contract. Due to this reason, successful bidding must ensure that the contractor can perform the work and achieve the desired profit. Especially in a period of limited construction opportunities, the competition is high. If the bidding is too low, may cause the contractor working for little or no profit, even working at loss. In other words, bidding may create a company, but also can destroy a company. The staff of a contractor must be carefully calculated the planning and cost estimates of each project in order to come up with the suitable bid. According to Walker (2003), the average percentage of work performed by subcontractors is between 40 to 70%, this result is from surveys which are conducted by The Associated General Contractors of American. The expenditure for subcontracted work can reach 60% to 80% of a bid (Ostwald, 2001). It is quite difficult to find a contractor that can perform all the work in a project, because a bidding construction project is a complex undertaking.
The contractor’s selection can affect the bidding process. One of the important factors that may affect the subcontractor to select the contractor is that the regulations imposed by the local authorities. This phenomenon is common, particularly in the United States.
Competition is an existing phenomenon. The competitiveness of the project depends on the cost effectiveness of the general contractor. And similarly, the cost effectiveness of the general contractor rest with the cost effectiveness of the subcontractor. The contractor engages a subcontractor and the owner engages the general contractor through the same way. But as mentioned before, not all of the work can be performed by the same subcontractor, and so it is possible for the contractor to employ other subcontractor or subcontractor engage other specialized subcontractor to finish parts of the work.#p#分頁標題#e#
Chapter 3
DESIGN COSTS
Construction project design conducts a comprehensive planning and specific arrangements for the process of the construction. Design has an important impact on project cost and it is the most important stage of the project investment. Whether the design will provide the most economic building or not is greatly depends on the client and his situation. The degree of the project definition is based on the percentage of completed architectural and engineering designs, and it gives useful information to the estimator to evaluate the cost of buildings.
During the design phase, design review submittals or status drawing should be issued at prescribed intervals and a set of documents will be sent to the permitting authorities for their review. According to Calin (2003), it mentions that the 90% design submittals should be the completed set of bid documents. At the beginning, the project manager has to determine the frequency of submittals to be prepared and the purpose of these submittals. On the other hand, once changes are needed, it is too late to make the changes during construction. It is less expensive to make the changes before the contract is let. When design is finished, a client may advertise and request proposals for competitive bids or a negotiated contract. Especially when project financing is based on public funds, the competitive bids are required.
Design costs generally equivalent to less than 1% of the construction project life-cycle costs, but it is account for more than 75% percentage of impact on this project. This shows that the design quality of the entire project is essential to the effectiveness of the design phase of the cost control to improve the design quality. But the building design process is a complex relation between skills, judgment, knowledge, information and time.
Calin( 2003) said, the optimum solution is that which is obtained within the constraints imposed by such factors as:
? Statutory obligations;
? Technical feasibility;
? Environmental standards;
? Site conditions;
? Cost.
In design cost, it is difficult to translate all tributes into a common unit value.
The role of the design cost planner is to provide information to the initial and future costs planning, depends on this, the design team can make a clear decision of overhead costs. The responsibility to provide the costs must be the whole team, not only the building estimator. However, the building estimator should be a main contribution people. According to Richard (2007), in theory the team will pool their combined knowledge for the benefit of the client, whose representative should wherever possible be a member of the team and play a part in the corporate decision- making process. As with any group activity, the composition of the team should be carefully planned to avoid vociferous member unduly influencing the final decision. This can influence the whole decision of the team and impact on the final cost of the building.#p#分頁標題#e#
Chapter 4
CONSTRUCTION COSTS
4.1 The Groundwork and Foundations
Before the construction start, estimators are usually consider all of the drawing details carefully in order to obtain comprehensive information, and then check to ensure that the drawings have been completed and have enough details to ensure that no lack of measurement information. During the start time, sometimes it is possibly to dismantle the existing buildings, the felling of trees, fences and other similar work. These costs are depends on the environmental conditions.
Some contracts involve alterations to existing buildings and these are sometimes termed “spot items” and are normally kept together in a separate section of the bill of quantities possibly headed “Demolitions and Alterations”, with some of the items covered by Provisional Sums, where the full extent of the work involved cannot be accurately determined. Many of the details relating to spot items will also need to be obtained on the site. A worked example of the measurement of demolition and alteration work is provided in Advanced Building Measurement. (Ivor, H. S 1999)
When visiting the site the quantity surveyor should also be on the look-out for any unusual items which affect cost, and which should accordingly be included in the billed description. A check in the type of soil and groundwater level comes into this category, unless the information is supplied by the architect, probably in the form of particulars from trial pits or boreholes excavated on the site. With landfill or brown field sites, it is also necessary to check on possible land contamination, with the likely consequential high cost of removing contaminated soil and remedial measures, including the extraction of landfill gases such as methane. (Ivor, H. S 1999)
Site preparation
The first building operation is normally the excavation of the topsoil for preservation over the whole area of the building and this usually forms the first excavation item in the Excavating and Filling section of the bill of quantities. Spreading soil on the site to make up levels is measured in m³, distinguishing between average thickness ≤ and ≥ 250. (Ivor, H. S 1999)
Excavation of Foundation Trenches
When measuring foundation trenches it is advisable to separate the trenched into external and internal walls. There the external wall foundation is of constant width and the site is level, its measurement presents no real difficulty with the length being obtained by the normal girthing method. Where the site is sloping and stepped foundations are introduced the process of measurement of the foundation trench excavation is more complex, since each length of trench will have to be dealt with separately. It is good policy to use a schedule for this purpose giving the lengths, levels, average depths within maximum depth ranges, and widths of trench for each section between steps. The sum of the length of all the individual sections will need to be checked against the total calculated length to avoid any possibility of error. (Ivor, H. S 1999)#p#分頁標題#e#
After measuring the excavation for external wall foundations, the internal wall foundations will be taken, and this will often involve a number of varying lengths and widths of foundations, which are best collected together in waste and the drawing suitably marked as each length is extracted. (Ivor, H. S 1999)
Disposal of Excavated Material
The subsequent disposal of excavated material forms a separate billed item in m³, either of soil to be stored on site, used as filling to make up levels, filling to excavations, or to be removed off the site. (Ivor, H. S 1999)
Basement excavation is measured to the outside of foundation in m³ stating the maximum depth range. Working space allowance is measured in m² on the external face of the basement walls, there the face of the excavation is > 60 from the face of the tanking or protective walls. (Ivor, H. S 1999)
It is usual to take the basement excavation as disposal of excavated material off site in the first instance and to later adjust the filling to excavation where appropriate. (Ivor, H. S 1999)
Earthwork Support
Support to the side of excavation is measured in m² to trenches, pits, and the like, where >250 in depth, whether the support will actually be required in the project or not. (Ivor, H. S 1999)
Concrete Foundations
Concrete particulars are to include the kind and quality of materials, mix details, tests of materials and finished work, methods of compaction and curing and other requirements, but much of this information may be included in preamble clauses or cross references to project specification clauses. Concrete poured on or against earth or unblended hardcore shall be so described. Concrete foundations include attached column bases, isolated pile caps and machine bases. Beds include blinding beds, plinths and thickening of beds. (Ivor, H. S 1999)
If the concrete foundations are reinforced with fabric reinforcement, the reinforcement is measured net in m² stating the mesh reference, weight per m², minimum laps and strip width, where placed in one width. (Ivor, H. S 1999)
4.2 External works
This chapter is concerned with the measurement of roads, drives, paths, grassed areas, planting of trees, shrubs and hedges, and fencing and gates. Demolition work is considered to be outside the scope of this book and has accordingly been omitted, but is included in Advanced Building Measurement.
In general, the sub-base or foundation for the road or footpath and the surfacing are each measured separately with a full description. (Ivor, H. S 1999)
4.3 Landscaping
4.4 Costs of mechanical and electrical work
Lighting and heating installations can be judged in terms of the adequacy of the internal environment to which they contribute.
The mechanical work is generally subcontracted out to mechanical specialties, which prepare detailed estimates for plumbing and heating, ventilation, and air conditioning system (HVAC). From the general contractor’s point of view, this simply transfers the preparation of the detailed estimate to another party, but it does not eliminate the need for estimating and analyzing the prices quoted. To accurately estimate plumbing costs, general contractors therefore should have field experience and a good knowledge of various plumbing systems, materials, labor, and equipment, as well as understanding of the drawing and specifications. (Calin, M 2003)#p#分頁標題#e#
Typically, costs of plumbing and sewage systems can be estimated in two ways: as a percentage of the total cost of a project, or as the grand total of the cost for the installation of required materials. Plumbing estimates as a percentage of the total job will range from 3 to 12% depending upon the number and type of fixtures required. However, in general, buildings that require a low percentage ranging from 3 to 7% include assembly, warehouses, banks, office buildings, shops, stores, and industrial buildings, where plumbing can be easily installed. On the other hand, buildings that require a high percentage ranging from 8 to 12% include nursing homes, hotels, hospitals, high-rise buildings, and studio apartments. The nursing homes, hotels, and hospitals generally require plumbing spread out over a large area, whereas high-rise buildings and studio apartments require extensive installations of plumbing in relatively small living areas. This percentage method is common for general plumbing estimates, whereas special items and conditions should be of interest to the subcontractor only. (Calin, M 2003)
Electrical work is a specialized trade and is often subcontracted out to specialized electrical subcontractors, either through a single contract with the general contractor or under a separate contract with a specialist. For a single contract, the owner has a single contract with a general contractor who is responsible for all construction work, including the electrical work. The selected electrical subcontractor commonly submits a lump sum price for the electrical work to the general contractor, who then adds his own overhead and profit to the estimate. The general contractor then submits the total amount in his bid price for the project. Alternatively, the electrical subcontractor may be required to tender the bid directly to the owner and be contracted directly with the owner. Under the latter condition, less responsibility is placed on the general contractor for the work performance by the electrical contractor. (Calin, M 2003)
The cost of electrical work is a significant amount, generally representing about 10% of the total project cost. (Calin, M 2003)
Like other construction divisions, the cost of electrical work includes materials, labor, and equipment costs. The materials costs for electrical components can be determined from current wholesale price, direct quotations from suppliers for special items (such as distribution equipment and lighting fixtures), and subcontract prices for special systems (such as grounding work). Materials for rough electrical work, such as distribution equipment, raceways, and wires, are purchased during the early phases of the project, whereas the materials for finish electrical work, such as receptacles, switches, and the various light fixtures are generally purchased and brought into the job toward the final phases of the project. (Calin, M 2003)
Labor costs are always the most unpredictable part of all construction operations. Electrical work is performed by electricians. Getting the prevailing rate for an electrician can be easy, but determining the productivity for installation can be very difficult. For electrical work, equipment costs are usually a small portion of the total direct job cost and are generally associated with the cost of lifting equipment or an elevating platform. The materials costs for electrical work, on the other hand, usually account for about 60% of direct job costs. (Calin, M 2003)#p#分頁標題#e#
The total bid package prepared by the electrical subcontractor will include all the direct costs for the work, jobsite overhead, general overhead, and profits. Included as an indirect cost under jobsite overhead would be costs for permits and inspections for electrical installations. Generally, the electrical contractor will be required to obtain any permits and make arrangements for official inspections of electrical installations. (Clin, M 2003)
These rates per square meter are for all engineering systems of specific building type applied to the gross internal floor area of buildings excluding professional fees and VAT. They are expressed in a range and are intended to provide a broad indication of the cost of the work. (Bryan, S 2006)
Public Service buildings ￡/m²
Ambulance stations
Banks
Council Offices 160-200
350-310
250-300
Fire stations
Magistrate courts 300-330
230-290
Police stations 220-260
Industrial buildings
Agricultural sheds 90-120
Factories
advance 90-120
high tech. 180-220
purpose built 140-180
Warehouses 90-120
Workshops (excluding machinery) 100-130
Educational buildings
Laboratories 230-300
Primary schools 180-250
Secondary schools 160-200
Universities 170-230
Leisure
Community centers 240-290
Gymnasia 160-190
Hotels 400-500
Public houses 200-270
Restaurants 230-290
Social canters 240-290
Sports halls 130-170
Swimming pools 180-240
Health and welfare facilities
Children's home 290-360
General hospitals 400-450
Health centers 190-250
Residential buildings
Local Authority and Housing Association schemes
high rise flats 150-190
4/5 person, two storey houses 130-190
4.5 Alterations and repairs
Chapter 5
COST OF THE EQUIPMENT
Modern construction is characterized by the increasing utilization of equipment to accomplish numerous construction activities. According to Means’ Illustrated Construction Dictionary, equipment refers to all the equipment, tools, and apparatus necessary for the proper construction and acceptable completion of a project. In a construction project, equipment costs are typically divided into portion. The first and bigger portion covers the cost of equipment and is often referred to as equipment cost. The cost of equipment is one of the major cost categories in a construction project. It represents the cost of acquiring the equipment and the cost of operating that equipment during the construction processes. The second and smaller portion covers the cost of hand tools. This represents a smaller portion of the project cost and often calculated as a percentage of payroll costs. It is added to the indirect cost under the jobsite overhead. ( Calin, M 2003)
Construction requires large quantities of materials handling, horizontally and vertically. In its simplest form, a construction operation is the moving of material from one location to another. The primary function of equipment is to handle and move varieties of materials around the construction site. For example, a construction site may need to be leveled, thus involving the excavation of soil material from one area and the transporting of the excavated material to fill in another location onsite. The complexity of an operation increases as the requirement for final placing or installation increases. An example is the erection of structural steel members in a structural steel frame building. The members are hoisted from the hauling unit or storage location onsite and are moved and placed at the desired final location on the building structure. Structural steel workers then bolt and weld the members in place. These examples illustrate how the primary function of equipment is to handle and move materials on a construction site. (Calin, M 2003)#p#分頁標題#e#
Many factors can influence the expected performance of equipment on a construction site. These factors can be group into three categories: site conditions, the nature of the work, and equipment characteristics. (Calin, M 2003)
Equipment selection must also consider the possibility of shared utilization of selected equipment. Cost is certainly an important consideration in equipment selection. (Calin, M 2003)
Equipment costs rank second behind labor costs in terms of uncertainty and their effects on the outcome of any anticipated profits from a job. This is again due to the unpredictable nature of production on a construction project. The understanding and knowledge of the components of equipment costs are necessary for a good cost estimate. It is also important to note that for any decision made in the acquisition of equipment, all costs should be considered and accounted. A contractor does not pay for equipment but the equipment should pay for itself. Costs incurred in the procurement of equipment must be recovered somehow in the profit or saving in other areas. Equipment can be acquired through three methods: purchasing, renting, or leasing. (Calin, M 2003)
The initial cost is the total cost a contractor pays to purchase a piece of equipment and have it shipped to a jobsite or equipment yard. This initial cost is the basis for determining other costs related to ownership as well as operating costs. Generally,
initial cost is made up of:
Price at the factory or used equipment price,
Extra options and accessories,
Sales tax,
Freight, and
Assembly or setup charges.
The initial cost is very straightforward, whereas the following costs require more analysis and computation.
留學生會計學專業畢業dissertation范文Depreciation in cost estimating has two aspects: a tax-deferred expense and the decline in market value of a piece of equipment due to age, wear, deterioration, and obsolescence.
There are three common methods for calculating depreciation expense for financial accounting purposes: straight-line, sum of years, and the Internal Revenue Service’s modified accelerated cost recovery system (MARCRS). Each involves the spreading of the amount to be depreciated over the recovery life of an asset in a systematic manner as prescribed by government tax laws. Each depreciation method selected produces different patterns of depreciation expense
per fiscal period. (Calin, M 2003)
Investment cost represents the cost of investment, or the typing up of a company’s capital in equipment. Investment cost is computed as the product of an interest rate multiplied by the value of the equipment. The value of equipment may be taken as the average value over the equipment’s life or, more realistically, as the depreciated value of the equipment at any given time. (Calin, M 2003)
Depreciation Expense per Hour of Operation = Original Cost/Total Operating Hour#p#分頁標題#e#
Depreciation Expense per Hour of Operation = ＄312,500/18,000 Hours = ＄17.36 per operating hours
Assuming 2000 hours of operation per year:
Depreciation Expense = ＄17.36 per hr. ×2000 hrs = ＄34,722
Figure 5.1 Computation for depreciation charges based on operating hours.
(Calin, M 2003)
Equipment operating costs are the direct costs associated with equipment operations. Unlike ownership cost, an operating cost is not a fixed cost but a variable one, directly proportional to the amount of work performed or operating hours. An operating cost is incurred only when the equipment is actually being used. Equipment operating costs include fuel, grease, oil, electricity, tires, and repairs. Operating costs vary from the type of equipment used, the nature of the work, and the working conditions of the equipment. Mobilization and demobilization charges and operator wages are not included in equipment operating costs. Like the ownership cost, the cost of operating equipment should be calculated on the basis of the work hour. (Calin, M 2003)
Fuel consumption can be closely monitored on the construction site. However, if this is not possible and no historical data exist, information from equipment manufacturers can be used for estimating. Fuel consumption depends on the application of the equipment. The application determines the engine load factor, which in turn controls engine fuel consumption. (Calin, M 2003)
Renting construction equipment is an increasingly popular procurement method.
Equipment rental rates do not include transportation costs, erecting and dismantling costs, insurance, or taxes. These costs must be determined and added to the rental costs in order to determine the total cost of acquiring equipment. (Calin, M 2003)
Chapter 6
MATERIAL COSTS
Materials can be judged in terms of their durability and freedom from the need for repair and maintenance.
The first part of an estimating task is to determine the amount of materials that will be required. Material quantities are the fundamental data forming the foundation on which all estimating processed build. This first step in determining the necessary amount of material is called quantity take off. ( Calin, M 2003)
Quantity take off is an extremely important task with direct implications for the many estimating tasks that follow it. The unit prices and the total prices of materials to procure, labor and equipment requirements and the scheduling of each activity are all based on the quantity take off. Therefore, it is clear that quantity take off is the foundation and the basis for all other estimating work and ultimately affects the total cost estimate of a project. Therefore, a quantity surveyor must be careful and through in her work in order to produce the most accurate calculations for the quantities of all the materials in the project. (Calin, M 2003)
1. Linear Calculation: perimeter of a Concrete Slab
60m +50m +60m +50m =220m#p#分頁標題#e#
2. Area Calculation: Surface Area of Slab
60m ×50m =300m²
3. Volume Calculation: Volume of Slab
60m ×50m 0.01m = 30m³
4. Unit measurement Calculation: Number of Type “A” Windows on 1st Floor
2 (North Wall) +6 (East Wall) +4 (South Wall) +5 (West Wall) =17 units
Figure 5.1 Examples of the four categories of calculations involved in estimating.
The calculations involved in quantity take off can be categorized into four basic components: linear, area, volume, and unit measures. When performing quantity take off, a quantity surveyor should visualize the entire project, thinking in terms of actual field procedures that will take place during construction. Quantity take off is also facilitated by the use of forms associated with each construction division. The purpose of using form is to standardize the work sheets by providing property assigned areas where specific information is to be written, thus organizing information in such a way that follow up and checking can be easily performed. (Calin, M 2003)
In addition to the calculation quantities obtained from quantity take off, the actual material quantities required for a work may be higher due to waste. Waste factor is used to increase material quantity, so as to ensure that enough material is procured to realistically complete the work. (Calin, M 2003)
Waste factors are usually listed by a percentage of the actual quantity of material left in place. That is, if the actual quantity of concrete required is 100m² and the waste factor is 5%, the amount of concrete to be procured should be 105m². (Calin,M 2003)
6.1 Concrete
Like other direct costs, the total direct cost of concrete work is the summation of all costs including labor, equipment, material, and subcontractors required to complete the work. Concrete is currently one of the most common and extensively used materials in construction. Cost of labor, equipment, and materials in concrete construction are relatively high. (Calin, M 2003)
Typically, concrete work consists of two major components, structural and non-structural. Structural elements are the major components in concrete building construction. They include footing. Concrete pilings, foundation walls, slabs in grade, columns, beams, above –grade floor structures, wall structures, abutments, roof structures, and other special elements such as stairways. The structural elements can be made from lightweight, normal weight, and heavyweight concrete. (Calin, M 2003)
Concrete work requires a significant number of crafts and the cost of crafts is normally high. An estimator must therefore include the costs of desired concrete construction crafts in the cost estimation.
Take off methods for Concrete Cost Estimating
One of the most common take off needs for concrete work is concrete volume. As shown in Eq. (6.11), concrete volume is simply determined by the multiplication of the length, width, and height (or depth) of a structural unit.#p#分頁標題#e#
Volume (m³) = Length (m) ×Width (m) ×Height (m) (6.11)
As shown in Eq. (6.12), concrete area is the product of the length and width of a structural unit.
Section Area (m²) = Length (m) ×Width (m) (6.12)
Even though the multiplication seems to be a simple task, an estimator can make mistakes due to unfamiliarity take off methods. There are three methods used to perform the quantity take off for the concrete work. They are differentiated by how the area of a structural component is determined, namely, the unit, perimeter, and centerline methods.
Concrete is one of the major and most common materials used in current construction. It is widely used because of its strength, durability, water tightness, and resistance to scratching and freezing, thawing, and some chemicals. Additionally, concrete is the principal material for many other construction components such as masonry units, mortar, grout, and precast concrete units. Typically, concrete gains more strength as it gets older. Its strength also depends on its major ingredients. (Calin, M 2003)
Concrete is basically a mixture of cement, water, and aggregates. Cement usually contains, by volume, from 10 to 15% of the total concrete mix. One cubic meter of cement is approximately 1510 kg. The most widely used cement for construction is Portland cement. It is usually made from limestone, clay, silica, iron ore, and other raw materials in a very high- temperature manufacturing process (1500C). According to the Portland Cement Association (2000), there are six types of cement commonly used in construction. ((Calin, M 2003)
6.2 Masonry
It is certain that being a good estimator requires knowledge and skills acquired through practice and experience. Particularly in masonry estimation, a good estimator needs to be well organized and proficient information collector. The major reason is that masonry contains a variety of products, unit types, unit sizes, specifications, and properties. This variety causes a difference not only in masonry costs but also in masonry productivity.
Masonry building elements, such as masonry walls, normally contain many components, namely, masonry nits, mortar, grout, and accessory materials. Masonry units include clay masonry units, concrete masonry units, clay tiles, ceramic veneer, glass masonry units, adobe masonry units, masonry stones, and special non-conventional masonry units. The most common products are clay masonry units and concrete masonry units.
The next basic component of masonry is mortar. Mortar is used to bed masonry units and to bond individual units into a combined component. In other words, mortar separates masonry units and, at the same time, holds masonry units together. Mortar also provides an architecturally aesthetic appearance and allows size variation in masonry units. (Calin, M 2003)
One important task of an estimator is to obtain the correct and updated cost data for materials and equipment. Generally, the cost of material is approximately 20 to 40% of the total masonry work. To obtain the most up-to-date and accurate material costs, an estimator can request a materials quotation and special discounts from a manufacturer or supplier. ( Calin, M 2003)#p#分頁標題#e#
Calculate the total cost of masonry. This can be accomplished by multiplying quantities of materials by unit costs in order to arrive at a sum for all costs. Unit costs also can be obtained from Means (1999) and Walker (1999), the estimator’s database, materials suppliers, manufacturers, or masonry subcontractors. For instance, if there is a structural-face-tiles wall area of 10 m² (6T series, 133 ×300 ×25 pieces/m², then the total materials cost is simply $535. Although this computation can eliminate some computation time, it has the disadvantage of not taking into account the exact number of masonry units an estimator needs for a particular job. (Calin, M 2003)
6.3 Wood
Wood is one of the oldest and most used materials for construction work. It is used extensively for temporary work, such as formwork and scaffolding, as well as for permanent work, such as floor, walls, and roof framing. The use of wood as the basic construction material has been due to its availability, strength, durability, and workability. In addition, the aesthetic nature of wood also makes it a favorite finishing material used in most home and office projects.
Applications of wood framing have been more prevalent for light construction such as houses and small buildings. (Calin, M 2003)
Wood framing work is often performed by crews consisting of at least two carpenters and may also involve common laborers who usually function as helpers. The labor costs for framing work will vary with the class of work, whether ordinary or first-grade quality, the complexity of the type of work, and whether tools are available and used. Ordinary workmanship is typically encountered in rough carpentry work in most building projects where cost is the main consideration. On the other hand, first- grade workmanship is often specified when quality is also an important consideration, such as in high-class residences and office buildings, especially in finish carpentry work. The use of modern tools can significantly facilitate the construction process, leading to increased productivity. For example, an electric handsaw can cut a 2 ×12 plank in four or five seconds, whereas it takes about a minute to do it by hand. Generally the use of power tools can increase productivity by 10 to 20 times (Walker, 1999). It must also be remembered that carpentry is a craft, therefore, the ability and experience of the carpentry can affect the productivity of the framing work and ultimately the cost for performing the work. (Calin, M 2003)
6.4 Doors and Windows
Door and windows are used to provide easy access and security to the users, while keeping unpleasant weather conditions outside and maintaining comfortable conditions inside. For these reasons, doors and windows have several components that serve various functions. (Calin, M 2003)
Major components of doors and windows basically include frames, glass, hardware, and other accessories. A frame, attached to the building structure, is used to provide support to a door or window. Hardware includes handles, hinges or butts, kick plates, locks, and bolts. Accessories a composed of weather stripping, thresholds, millions, sills, stools, locks, handles, and so on. Weather stripping is used to prevent heat loss and the intrusion of insects, dust, noise, and moisture. A threshold and a door sweep are used to prevent heat loss around the edges of the door. (Calin, M 2003)#p#分頁標題#e#
Generally, quantity take off is simply a counting of all items required for doors and windows. Pricing provides costs of all items by multiplying each materials quantity by the unit cost of that item and totaling all materials costs. Unit costs can be obtained from the estimator’s database, suppliers, manufacturer’s catalogues, Means (1999), Walker (1999), or other sources. The estimator, however, must keep in mind that the Mean and Walker references typically contain average industry cost data, so adjustments must be made for the particular company crew and project location. Table 6.41 presents five major steps in cost estimation for doors and windows.
Table 6.41 Major Steps for Door and Window Cost Estimation
Step Description
1 Specifications and drawing
2 Takeoff pricing for doors, window, accessories (number of doors, windows)
3 Takeoff pricing for glazing (width ×height, m²)
4 Takeoff pricing for accessories (m)
5 Total costs of doors, windows
Most of the items covered in this chapter are finished by materials suppliers and installed on the job by carpenters hired by the subcontractor. In the estimate, labor costs should be included under their proper trade. Quantity take off for doors and windows means simply counting or copying all required items from the schedules and specifications to a takeoff sheet, especially for residential construction. The estimator counts the number of exterior and interior doors and lists the quantity by size, materials, unit, and installation cost.
Similarly to that for metal doors and frames, quantity take off for wood and plastic doors requires the estimator to identify openings, combine all the quantity surveys, check specially requirements, and determine accessories. For entrances and storefronts, the estimator should submit the plans and specifications to an installer for takeoff and pricing. The quantity take off for entrance units determines total length of framing, number of joints, hardware, threshold, and closers. The quantity take off for storefront units determines height and width; length of intermediate, horizontal, and vertical members; and number of joints. For metal and wood windows, the estimator finds basic information regarding windows in the window schedules and indentifies all details in the plans and specifications. Major items for metal windows include materials, glazing, screen, trim, gauge, and hardware. The estimator also needs to know the type of glass required and its installation procedure. However, wood and plastic windows are sold as complete units including hardware, weather stripping, and glazing. (Calin, M 2003)
6.5 Metals
Structural metal products are typically made of various materials including aluminum, brass, and bronze, but the most common one on the market is steel. Structural steel has been increasingly used recently in multistory buildings due to its better productivity and flexibility in shapes and styles. Structural steel is also commonly integrated into concrete and masonry construction to provide additional support to buildings and to increase the size of building structures. Steel is used for various building structures besides multistory buildings, such as theaters, auditoriums, gymnasiums, stadiums, and churches. (Calin, M 2003)#p#分頁標題#e#
The steps for estimating metal framing include taking off the quantities from the plans, computing the weights of various sections, making the shop drawings and detailing the steel, and estimating the cost of shop fabrication, freight, trucking, and erecting the steel on the job. Quantity take off may have a definite sequence composed of columns and details, beams and details, and bracing and flooring. A complete take off floor by floor is required. Using specifications and other contract documents, the estimator needs to have a complete list of all structural steels, ornamental metals, and miscellaneous metals for the project. Each class of work such as columns, girders, and trussed should be kept separate since each involves different labor operations in fabrication and erection. Special shapes and composite members require extensive fabrications, so they should be listed separately from the standard mill shapes. One of the most important aspects of an estimate is to know which work items are subcontracted. In some circumstances, the general contractor may subcontract the metal work with fabrications and installations to specialty contractors. The estimator must also create a list of all those items on the drawings not identified in the specifications. In addition, the estimator pays attention to numerous miscellaneous items such as bearing plates, loose lintels, and anchor bolts. All standard connections for detailing can be referred to in the American Institute of Steel Construction (AISC) standards, with the exact lifting methods.
The estimator needs to compare items that subcontractors have quoted. In most cases, the estimator will find that more than 80% of the work will be at the same cost. After making comparisons, the estimator should contact each subcontractor to clarify the individual quotes. Many estimators will have checkmark placed next to the items that obvious and do not need to confirmation or clarification. Prior to bid submission, the estimator needs to call subcontractors or fabricators to clarify any unchecked items that are either in the original quote or are outside the scope of the project. (Calin, M 2003)
Chapter 7
LABOR COSTS
In today’s fast-paced industrialized age, where many of the products we see are increasingly being mass produced in factories by machines, a building still remains as one of the few handcrafted products put together piece by piece by craftsmen. The construction industry, to which these craftsmen belong, is one of the most labor-intensive industries in the US. The labor cost component of a building project often ranges from 30 to 50%, and can be as high as 60% of the overall project cost. Therefore, it is clear that construction labor is a vital component of a construction project. (Calin, M 2003)
Labor costs in construction are determined by two factors: monetary and productivity. The monetary factor is related to hourly wage rates, wage premiums, insurance, fringe benefits, and taxes. Estimating the components of the monetary factor is more difficult in construction than in any other YS industry. This is due to the variety of work involved in construction, as well as the many types of trades involved. The problem is further complicated by the presence of the unions with their craft structures and collective bargaining processes. Although the computational process of this component seems complex and tedious, it is only a matter of accounting as the needed number (such as wage rates, fringe benefits, and insurance). The second factor, which is much more difficult to deal with, is productivity. (Calin, M 2003)#p#分頁標題#e#
The formula for computing the total cost of labor is quite simple. It requires the knowledge of the total work hours or labor hours needed to perform all the tasks and then applying the corresponding wage rates. The formula for calculating the total cost of labor is shown in Eq. (6.1)
Total cost of labor = ∑ total work hour (i) × wage rates (i) (6.1)
Determining the total work hours for a task involves a knowledge of the quantity of work required for the task and the productivity rate for the specific crew that will be performing the work. The formula for calculating the total work hour is shown in Eq. (6.2)
Total work hour = ∑ quantity of work (i) ÷ productivity rate (i) (6.2)
Chapter 8
INSURANCE
The contract documents stipulate for the owner’s protection that the construction contractors must carry various types of insurance. Insurance is a two-party instrument. 留學生dissertationWith an insurance policy, the specified losses encountered by a general contractor and various subcontractors and suppliers become the responsibility of the insurance company. (Calin, M 2003)
Along with the insurance required in the contract agreement provided at the invitation to bid, state or governmental agencies often require additional types of insurance. All this insurance is not free. It costs money and that cost must be estimate. The cost of insurance is an important cost component and is estimated to vary between 2 and 5% of the direct contract. It is usually included as a line cost items in jobsite overhead. (Calin, M 2003)
Insurance cost represents the cost of life, theft, accident, and liability insurance for equipment. Generally, insurance cost and taxes for equipment are annual costs, as a percentage of the initial cost. In the US, insurance is about 3%, taxes are about 3%, and storage cost is about 1%. (Calin, M 2003)
7 Professional fees
8 Other consequences costs
Similarly the costs of buildings do not cease with the costs of construction but continue throughout the life of the building in the form of maintenance and other running http://www.mythingswp7.com/dissertation_writing/Accounting/costs, the costs of adaptation to meet changing requirements and the costs of the inconveniences imposed by the building on the process and procedures carried on within it.
9 Conclusion
10 Reference
