TRENDS, APPROACHES AND BEST PRACTICES IN DRYWALL ESTIMATING -A practical perspective
Growing industry The drywall industry has enjoyed tremendous growth since the turn of the 20th century due to refinements in manufacturing processes, coupled with the need for high quality, low cost buildings and houses (National Occupational Classification, 2011 as developed by Human Resources and Skills Development Canada/Statistics Canada and The Gypsum Construction Handbook, 2014). It is estimated that about 90% of interior finished surfaces of buildings constructed in North America use gypsum products in one form or another. The gypsum industry continues to develop new and innovative ways to provide high quality products and services to achieve code requirements of officials, designers and others.
Estimating procedure For the quantity take-off process, the estimator’s job is to figure out the quantities of materials based on project drawings, specifications and scope of work. One of the commonly used estimating techniques for drywall estimating entails preparing quantities from scaled drawings, using either printed drawings or on-screen take-off procedures. This practice is typically used when a speedier take-off is desired compared to the traditional method of reading dimensions. It is paramount that the estimator be aware when scaling drawings to check that
he/she is using the correct scale, and whether the drawings themselves are correctly scaled. If the drawings are out of scale, the estimator needs to make adjustments on measurements.
40-storey building with 15 typical floors, the number of floors to be included in take-off process will be reduced from 40 to 25, so by 37%.
Residential drywall estimating Estimating quality Quality control is an essential element of good estimating practices. During the procedure of determining quantities (the take-off process), it is very important to follow consistent steps, forms and documentation for all projects. When preparing take-offs, it is a good practice to organize the estimate so that it follows the construction process of dry-walling as it would occur on the job site. The objective of this practice is to minimize the possibility of missing elements or quantities from the estimate. For drywall estimating it is always recommended that the estimator begin take-off calculations from the lowest level of the building element and move to upper levels. In drywall takeoff, it is recommended to always start with the building shell, following with demising and corridor walls and ending with the interior partitions and ceilings. In multi-floor buildings, it is more efficient to prepare the quantity take-off floor-by-floor. Where a building has multiple, identical floors a take-off of a typical floor is prepared and applied to all other similar floors. For example, in a
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In residential projects, there is a significant difference in the materials used, compared to those in high-rise, residential projects. In housing projects, all framing work is generally installed by carpenters and the estimator has to establish the quantities for various combinations of materials i.e. drywall, insulation and vapour barriers. Therefore, the most efficient technique of estimating, relies on calculating all the materials that form the intended final product. Working with assembly quantities increases the productivity of the estimating process, which is very important in terms of increasing the number of projects priced and increasing the accuracy of measurements. The waste factor is always related to the company policy, difficulties of the project and qualifications of the working team. Assembly quantities are measured either as length or area, depending on the specific nature of any job. Drywall jobs consisting of a standard height can be measured and priced out on a length basis. However, most drywall assemblies are determined as area by multiplying the wall length or perimeter by the height. In order to determine the lengths of different assemblies, the estimator has to apply different types of measurements, such as on-center
