What Is Quantity Takeoff?
Quantity Takeoff can simply be understood as estimating materials from drawings or models, then recording in the volume table. It is an estimate of the physical materials that engineers and architects design for the project. Its result is a table with detailed information about the volume and type of materials that need to be prepared before construction.
No matter how large your project is, we must accurately determine the volume of materials to prepare for the construction process. Construction Takeoff is an important stage and needs to be done correctly. Whether it’s a small unit or a large, complex subdivision, it always starts with retrieving the data, understanding the work you have to do, and predicting its quantity and cost.
Through the image, we can understand that the Material takeoff directly affects the project’s cost estimate.
Quantity Takeoff Using BIM (Building Information Modeling)
It is known that most projects that run overtime or over budget come from inaccurate construction material estimates. The development of BIM makes the estimation of materials completely automatic and accurate. It can aggregate information about volume, price, material type, etc. to improve accuracy and limit over budget.
According to some surveys, the time spent on quantity takeoff work has been significantly reduced, even up to half the time when applying BIM instead of using traditional methods.
Survey participants also said that some of the best software for quantity takeoff are Autodesk Revit, Navisworks, Assemble and Vico.
BIM Quantity Takeoff Implementation Steps
Currently, the application of BIM to volume measurement is basically done in the following three steps:
Step 1: Build 3D models in the software from 2D drawings. In order for the 3D model to automatically extract the mass measurement results, the construction of the 3D model needs to follow basic principles such as component identification, detail level, etc.
Step 2: Customize the software to give relevant work titles and names in accordance with the prescribed standards;
Step 3: Export data from 3D model to Microsoft Excel software. From the table of quantities obtained, users can use it to determine the time and resources for each individual component quickly, thereby serving as a basis for construction progress, cost estimates, etc.
All software used in BIM is capable of providing dimensions of objects, area and volume, and volume of materials. However, these software still have some limitations when combined
With estimation software to prepare costs related to the project, in many cases, the object dimensions exported from BIM do not meet the level of detail that the estimating software needs to apply a unit price for a project. specific job. Currently, to overcome these limitations, valuation engineers need to participate in the design process, collaborate, and exchange necessary and continuous information with architects to build BIM models to achieve the purpose. Determine the appropriate cost estimates for each phase of the project.
Quantity Takeoff Methods
Although the development of information technology has had a huge impact on construction projects, greatly increasing the speed and accuracy of quantity takeoff. However, the human factor is irreplaceable. It can be said that technology is only a tool to assist us in the implementation, while the quality and accuracy of the material estimation work depends on the qualifications and techniques of the estimator. Today, the estimation methods being used are manual and digital.
1. Manual method
This is the most basic method that has been used since a long time ago, until the assistance of computer technologies. It is completely done manually, by reviewing each drawing, specifications, contract, the scope of work. Then use the data you gather to determine the type of materials, quantities, and work needed to prepare the project.
This method requires a lot of meticulousness on the part of the estimator, in addition, they must also be able to read plans, specifications and calculate with complex equations to make an accurate estimate. Best. Errors are inevitable when we do such a large amount of work. The biggest disadvantage of this method is the “time” factor because of the repetitive work of reviewing drawings and manually entering calculations. It can also cause delays if the data is wrong.
2. Digital Method
Performing material estimation by the digital method has been widely applied since the 80s – 90s, by applying CAD (Computer-aided design) through computer analysis and database application. The difference between manual and digital methods can be clearly seen when you do it on a large project. The computational speed and sophistication of computer technology greatly reduce the time, and the accuracy is also extremely high.
It can be said that the disadvantage of this method is that when we change from the manual method, the challenge in software application, the cost and time of learning and training about the software. Therefore, for companies that always have large projects and need to perform estimates on a regular basis, training estimating engineers is very necessary.
If the manual quantity takeoff method takes too much time, and the digital method requires a lot of software costs, which method will small and medium businesses choose? Nowadays, outsourced quantity takeoff teams are born which is the short-term and best method for them. Service companies were born to serve businesses that currently lack the position of estimating engineer. They are engineers with long-term experience in the field of BIM that will help you shorten the time as well as reduce costs for projects.
Need Support In Implementation Of Quantity Takeoff?
Performing a construction takeoff requires a lot of experience, skills and observation. This is an important component for making proposals for the project. If your business doesn’t already have specialized estimating engineers, outsource experienced teams to speed up the project.
