What is Quantity Takeoff and what is it for?

Quantity Take-off refers to the automatic extraction of the quantities contained in a BIM model, which are necessary to estimate the final cost of the work. Read the article to learn more

Over the years, the world of construction has undergone enormous transformations and has evolved thanks to new technologies. One of the most obvious examples of this evolution is the Quantity Takeoff.

This article explains what a Quantity Takeoff is and provides useful information on what you need to know about this topic. In the meantime, I recommend that you immediately download a 5D BIM software to test in first person the simplicity of obtaining an automatic quantity takeoff.

What is a Quantity Takeoff

Quantity Takeoffs allow quantity surveyors to generate a detailed bill of quantity directly from the measurement data contained in a CAD or BIM file and is based on a detailed analysis of costs to be considered within a project.

It is easy to understand how essential this phase is, as it gives the possibility to facilitate the budget management, avoiding waste due to inaccurate estimates.

As mentioned already, the Quantity Takeoff is the fifth dimension of  BIM (BIM 5D). Thanks to this process, it is possible to extract only the metric information useful for the definition of the construction costs directly from the BIM model.

In this way, it is possible to associate the related prices to each item of the BIM model, making the cost estimation process more efficient and easier to update. In fact, you just need to change something in the model, a measurement for example, and the estimate is updated automatically, minimizing the errors that can arise from manual data entry operations.

Quantity Takeoff | Automatic bill of quantity

The advantages of adopting a Quantity Takeoff in construction estimating procedures

The advantages of using Quantity Takeoff are obvious.

Compared with traditional methods, we can notice that 5D BIM allows easier and more efficient calculations and minimises the possibility of introducing error even in very complex construction or infrastructure projects thanks to automatisms and improved data control functions.

In fact, if we look at the traditional methods used to draft an estimate you’d need to:

• precisely identify all tasks that require price list items
• measure up all quantities to be included in the BoQ software
• organize the data obtained in a logical and sequenced order
• evaluate materials, measurement rules and units of measurements.

Of course, in all the above points, the higher the accuracy, the lower the risk of making mistakes.

With a compuiter aided Quantity Takeoff, the steps are roughly the same, but the level of detail increases and the risk of errors are greatly reduced. The automatic connection that each element has with the single cost estimate item provides an added value and is of great help.

The list below explores the main advantages obtained with Quantity Takeoff:

1. cost management – all costs are directly tracked and controlled and automatically updated, bringing benefits both to the construction company and to the client
2. rapid identification of quantities – the measurements are directly and automatically derived from the model so as to improve the workflows among the team members
3. fast calculation – calculation and data entry take place quickly thanks to the BIM procedure, optimising working times and, therefore, costs
4. better quality of work – greater control and faster processing make work more productive so as to lead to further money savings
5. more detailed assessments – 5D simulation models in combination with the entire BIM process allow to reach higher measurement details, so as to improve accuracy and cost predictability.

The high precision obtained with the Quantity Takeoff allows to obtain further advantages from the management point of view of the project. In fact, designers can accurately evaluate all the decisions during the design phase already, minimizing the variations during the executive phase.

Quantity Takeoff | How to take measurements directly on the BIM model

How to perform Quantity Takeoff

If you want to benefit from automatic cost estimates, then you should use a 5D BIM software. This is part of a series of BIM software that allows you to dramatically improve the quality of your work. In detail you can:

• open the BIM model in IFC format and link the objects with the relative reference price list item (or more generally a price)
• identify all similar entities in the model in order to speed up the association
• define measurement rules (applying predefined templates or creating new ones)
• automatically obtain the bill of quantity of the project
• keep the calculation up to date automatically every time the model changes
• print, export and reprocess the bill of quantity obtained automatically.

The use of BIM tools, including 5D modeling software contribute to more efficient workflows, although some greater effort is necessary in the initial stages. However, you should not feel discouraged by this aspect as you will be largely rewarded.

You can try out in first persone the benefits of 5D software for bill of quantity of BIM models in IFC format by downloading the trial version and using it for free for 30 days.