By: Nicanor Wong Arch
jnwong@caplima.pe
Summary: Although it is impossible to believe, studies by Soibelman (Soibelman, Lucio, 2000) and Skoyles (Skoyles, Edward : 1996), studies in Brazil and England, respectively, show that in the construction activity there is a 30% waste., ie, in three buildings, one goes to landfill.
Soibelman tells "... I have lived construction sites and all my life I've had the feeling that something is wrong in how we're doing construction and I have always been challenging. " Indeed, construction, unlike other areas, it will focus primarily on profitability, but is hidden within this range number is commonly called "waste."
If approximately 70% of the cost of construction is referred to materials, handle the remaining means to control a large percentage of the total cost. The manual states that should be included within the construction budget by 5% of wasted materials, but ... Is this real? Actually, no, as demonstrated by studies in the field.
Sobielman waste means using more than that does not generate any value, or added or the final product. For the study by eight months surveyed small-scale works. The first thing he did was measure and count everything that had to commissioning work. Calculated how much material had to be used to deliver part of a building and then reviewed all receipts for all materials so far, determining how much was spent. The difference is the waste. Sobielman focused on certain important items: steel, concrete, cement, mortar, sand, without finishing and partitions.
Bloess According to studies and rovings (Bloess and rovings: 1984) is within the concept of waste, time. Between 20% to 30% of the time an operator is lost due to lack of tools and materials, about 2 hours of lost wages obtaining the materials and tools you need to work. WASTE CLASS
One is natural, inevitable, for which the investment by getting rid of him is greater than the savings you get to remove it.
Another is the indirect one that is hidden from factory production to the location on site, for example, make slabs slightly thicker than those specified in plans without this need.
indirect wastage is due to the way it is for instance a carry the same where the pieces of masonry to crack. You may also be due to their origin, either by the manufacturing process, delivery, etc. Skoyles
recorded an interesting fact in their investigations. Studying the aggregates, the use of the sand had a 15 to 20% of waste that could not justify as cement mixtures were made correctly. Someone discovered the cause. The trucks brought a huge water tank to be cubed initially, to download m3 of sand was unloaded also the cylinder, stealing 15% of the material. It took 5 years to realize that paying the cost of water to sand.
But waste is not only measurable in building materials or man-hours but also in natural resources, namely energy, water and other inputs which gives us the planet to make them. WASTE AND PRODUCTIVITY
Among the conclusions obtained by Soibelman found that in the place where there is less waste had increased productivity and conversely, where more waste, lower productivity. But the consequences were not so alone there. Found that in the places where they had greater waste was where customers had more complaints after delivering the work. Clearly, if you are doing wrong things, the end is bad.
According to data collected in 2000 found that, in theory - what the books say construction - the cost of materials plus labor amounts to about 80% of the total cost of waste with a margin of between 5% to 12% of the total cost. Now imagine - within the theoretical - that the profit margin you add the indirect cost rate (by saving waste) close to zero. The utility for the general contractor is very interesting. If the profit for a U.S. construction company is 3% and 7% in Mexico imagine that with a low percentage of waste and increased productivity by 6% let us add extra. Who can get this benefit for the company? The first conclusion
Sobielman reporting is a waste of up to 8 times the value of the compositions of the costs, then how to explain the numbers that appear in books with an estimated 5%, 7% or 10% depending on the material that is used? Comes from an estimate based statistical data collection and the materials inventory versus those executed in each process. Empirical data collected so since the obscure inventory control services of value in the process of receiving, storage, transfer to the workplace, unidentified material substitution ... This defect does not have a hidden value but has no impact on book value, yes it is economically profit margins and quality. Not control the waste generated in low productivity work, such a poorly designed layout (physical distribution of materials on site), lack of adequate tools and materials, time wasted in transporting materials or pending material.
Sobielman concludes: "... the waste of material is mainly caused by poor management practices and not by the use of skilled labor ..." and continues: "... there is no method available to control the material. Consequently there is a lot of waste and a lack of knowledge on the impact of waste. " Under construction companies realize the importance of Logistics in work, as "... the Productive Chain (Supply Chain) dealing with the planning, implementation and efficient control of normal and reverse flow and storage of goods, Related information and services, from their point of origin to point of consumption, by way of fully satisfying customer needs "(Council of Supply Management Professionals, 2003). Which will be covered in another article.
SOURCES:
- Soibelman, Lucio. 2000. Waste Material in the Construction Industry: Analysis and Control. Cuadernos FICA. Mexico.
- Skoyles Edward. 1982. Waste and the estimator. Chartered Institute of Building. England.
- rovings, James and Bloess, John. 1984. Modern Innovations in Scheduling Techniques. AACE Transactions. USA.
- Council of Supply Management Professionals. 2003. Fundamentals of Supply Chain Management. Educational Workshop. USA.
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