SUB-WORK / SUB CONTRACTOR

A subcontractor is a person or a company hired by a general contractor to perform part of the work of a construction job. For example, a contractor might be building a house, but might hire a firm or a person specializing in electrical engineering to install the electrical systems needed in the house. Generally the subcontractor will either relieve the main contractor of part of the building work, or will be able to perform work at lower expense or at a greater skill level than the general contractor could.

Often, a subcontractor, whether an individual or a business, forms relationships with several general contractors. The general contractor working with a subcontractor does not employ the subcontractor as a regular employee in most cases. Instead the subcontractor is either an independent contractor, or is a company that provides its employees with required benefits like health insurance coverage.

Not having to extend benefits to a subcontractor is one way that the general contractor saves money on a job. However, if problems occur because of faulty work on the part of the subcontractor, usually the general contractor is held liable for such problems. The general contractor may attempt to seek redress with the subcontractor, or have defined terms in the contract with a subcontractor stipulating that the liability would be more evenly shared.

Frequently, though, hiring a subcontractor, or several, is a way to avoid problems in construction. Specialized workers like plumbers, electricians, or people who install heating and cooling devices, often called HVAC workers, tend to have more knowledge and training in their given field. While simply building something requires training and knowledge, people who are specialists better perform certain types of work.

The subcontractor and the general contractor are served well by being able to form good working relationships with each other. For the general contractor, access to a reliable subcontractor can mean finishing jobs on time and on budget. For the subcontractor, a good reputation among contractors means greater opportunities for consistent work.

A subcontractor often holds licenses in his or her specialty field. He or she might hold a general license to conduct work in a state, and also hold advanced licensing. Such licensing implies a certain amount of hours practicing his or her trade and knowledge regarding state building codes.

In some cases, one may also refer to a person hired for a few days of work, without a specialized field as a subcontractor. Really the more accurate term is independent contractor. The person is usually a temporary employee of the contractor, hired to finish work on time, or to temporarily replace another worker who is ill. This type of subcontractor may not have a general contractor’s license but may be hired for his or her carpentry skills.

TYPES OF ESTIMATES

There are several kinds of estimating techniques; these can be grouped into two main categories:

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.

Detailed Estimate

A detailed estimate of the cost of a project is prepared by determining the quantities and costs of everything 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

1. 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.

2. Total Quantity Method

In the total quantity method, an item of work is divided into the following five subdivisions:

1. Materials
2. Labour
3. Plant
4. Overheads
5. 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.

TESTING CONCRETE AGGREGATES

Samples of the fine and coarse aggregates approved by the Engineer shall be kept on the Site and shall give a fair indication of the approved quality of the aggregate for comparison with the aggregate delivered during the course of the works.

Should a sample fail to comply with any of tests, the Engineer may at his own discretion reject the batch from which sample was taken, or order it to be washed and/or screened, or permit such to be used with variations in the proportions of the concrete mixes specified, all a the Contractor’s expense. Any batch of aggregate rejected by the Engineer shall be removed from the site forthwith and replaced entirely at the Contractor’s expense.

All sample and testing of aggregates shall be carried out in accordance with ASTM C33.

Preliminary aggregate tests

As soon as the source of supply of aggregate have been approved, the Contractor shall instruct the testing agency to carry out the following tests for compliance with “Specification of Concrete Aggregates” (ASTM C33).

• Sieve analysis
• Tests for clay silt and dust content
• Tests for organic impurities
• Tests for salt content (chloride and sulphate ions)

The results of these tests shall be submitted for approval as soon as available. Test (1) and (2) with tests for the moisture content of each aggregate shall be carried out on the sample used for each trial mix.

Testing samples of aggregate

The contractors shall carry out such tests on aggregate samples as are necessary for the production of the specified concrete. The minimum incremental frequency of tests on each type of concrete used for the works shall be:

• Sieve analysis: at least once weekly
• Moisture content: at least once weekly
• Tests for clay silt and dust content: at least once fortnight
• Tests for organic impurities: at least once monthly
• Tests for salt content (chloride and sulphate ions): for every 500 cubic meters of concrete placed.

If for any reason the Engineer is not satisfied with the works concrete, he may instruct the Contractor to further increase the rate of sampling. Conversely, the rate of sampling may be reduced by the Engineer when consistent high quality been well established.

TYPES OF CONSTRUCTION

Construction is an industry method that consists of assembling or building infrastructure. It has many types such as heavy or civil construction, building construction and industrial construction. Construction works are managed by project managers and supervised by a construction engineers, construction managers, project architects or design engineers.

What is heavy Construction?

Heavy or civil construction is a procedure of adding infrastructure to the environment of a building. The builders are usually government agencies both at the local or national level. These also have legal and financial considerations. This project primarily serves the public interest. They are undertaken and supervised by some large private corporations such as power companies and whoever oversees the construction of access dams, roads and railroads.

What is Industrial Construction?

Industrial construction requires highly specialized skill in construction, planning and design. Holders of this project are normally industrial, for profit or large corporations. This corporation can be found in industries such as chemical, medicine, power generation and petroleum manufacturing.

What is building Construction?

Building construction is a process of adding small or big structures to land or real property. Most of the building construction jobs are small reconstructions like adding bathroom or reconstruction of a room. Often times, the titleholder of the property acts as a designer, paymaster and labourer for the entire job. However, all the building construction jobs include several elements in legal consideration, financial and usual design.

Building constructions are procured publicly or privately using different delivery methodologies such as management contracting, hard bid, construction management at risk, design & build bridging, and negotiated price.

Residential construction technologies, resources and practices should conform to the codes of practice and local building authority regulations. The materials used are widely accessible in the market. The common materials used are timber, stone and brick. The cost of construction is on a “per square foot” basis.This is since homes can vary significantly on local site considerations, conditions, and economies of scale.

PREFABRICATED CONSTRUCTION METHOD

Prefabricated construction is a building process in which elements or modules of the structure are prefabricated at plants, and then transported to the construction site for installation. Using this method can reduce the time of building, also saving construction cost. Prefabricated construction is now widely applied for new houses or other building structures like bridge, tunnels, culverts, water supply system.

The benefits of prefabricated construction method are from the fabrication of standard components on factory floor. This production is less time consumption compared to actual condition of construction process. The prefabricated elements are transported to the site for installing process. At the site, the modules are unloaded, moved into position with the support of heavy cranes, and assembled to form a designed building.

Together with the fast assembly, prefabricated construction also saves a lot of money on the construction project. By using standard patterns, the building materials are saved at the manufacturing factories. This help to reduce the waste in formwork and other materials that can occur during traditional building procedures.

Another considerable profit using prefabricated construction method is the energy efficiency. Because the prefab elements of a panelized home are precut, they fit snugly together, making for a tighter edifice. This means less effort for heating and cooling resulted in lower energy bills.

The rapid development of prefabricated houses has led to the increasing of construction templates that homeowners have more choice for designs of their houses. By combining these templates, it is possible to design the layout of the house, specify the dimensions of each room, and build a home that is exactly to the specification of the owners. There are also complex building plans for prefabricated constructions that can be adjusted slightly and still have the benefit of using materials of standard lengths, widths, and textures.