Quantity Takeoff in Construction

Quantity takeoffs make up an essential part of the planning and construction stages of projects. Getting your quantity takeoff done right will help to enhance the bidding process and construction to follow. 

This part of early-stage planning is crucial for understanding the requirements and scope of the project ahead. Collecting the construction data and achieving total accuracy here can really make or break a project as this process affects the entire construction chain that follows.

Quantity Takeoff

What is a Quantity Takeoff?

Also known as estimating takeoffs, construction takeoffs, or material takeoffs, this process is about understanding the needs of a construction job ahead. They provide detailed measurements of the materials and labour that you will need to complete a construction project. 

They are also used in planning, such as in making room lists to get your areas under control. Quantity takeoffs are mostly based on the physical, material requirements of a project, but they also cover other aspects such as rooms. 

Before you start construction, you need to do a quantity takeoff in the pre-construction planning phase. It needs to include material estimates as well as anything else that the project requires. To produce quantity takeoffs, estimators will use blueprints or models and make a list of the materials needed to achieve the end-result. 

While this was traditionally done manually (requiring a lot of skill), the digitisation of quantity takeoffs has advanced the process and made it far more accurate. This has included things like BIM, which helps to achieve the most accurate estimation results through detailed systems and models, and automated calculations. 

 

Who Does Quantity Takeoffs?

Simply put, all parties involved in the front-end of a construction project need to be involved in the quantity takeoff. The key people involved in doing a quantity takeoff include architects, engineers, contractors, and estimators. 

To produce accurate bids and budgets, it’s important to achieve a realistic quantity takeoff. This is essential for figuring out financial costs and to help understand the scope of the project. No matter how big the project is, this is always the essential starting point for all parties involved in construction projects. 

 

Conducting a Quantity Takeoff

Doing a quantity takeoff is a specialised skill that requires time and resources. While you can perform it manually, doing it digitally enhances the accuracy of the process. This is because it reduces the scope for human error. 

Any wrong calculations done during this phase can snowball into significant, costly mistakes so you want to make sure that your takeoffs are as accurate as possible. 

Whether you choose to do it digitally or manually, the formula involves the same two parts:

 

1. Input

To achieve an accurate quantity takeoff, you need to input the correct data needs into the models. Whether you are working with a hand-drawn sketch or a detailed 3D building model, it’s crucial to manage the data correctly. 

You need to use precise information here. This is where tools like bimspot’s quality checks can come in handy. It will help you to ensure accurate quantity takeoffs due to high-quality planning.

The estimator is not usually in charge of preparing the concepts or designs so they need to be able to trust the data they are given. So, you want the planner to deliver high-quality data and, to achieve this, it’s best to use quantity takeoff software.

This process can further be enhanced through features like model checks. With bimspot, you can achieve this through clash detection and model checks that use default or custom rule sets. 

 

2. Output

The output stage is about taking the concepts from planning and converting them into the physical requirements for the project. 

Basically, you take the building idea and estimate the exact material quantities required for the project to take shape. Having accurate material estimates is essential here. This is the part of the process where you can create actual figures and realistic estimates to give life to the project. With this data, you create your bids. The more accurate this process, the more successful your bids will be. 

The output process is also often an input into a different tool. For example, you can input the data into estimation software to create a costing. Using software like bimspot allows you to do this as seamlessly as possible through its open API.

Key areas of focus during this process include identifying the materials, quantifying this data, and aligning this data to a pricing system. This will help you to achieve a realistic project proposal.

 

Quantity Takeoff Models

If doing a quantity takeoff from 2D plans, there are a number of base formulas and approaches you can use to do quantity takeoffs. These include calculating things unit counts and finding linear length, surface area, weight, and cubic volume of materials needed. 

The idea behind this is to transform two-dimensional plans into a three-dimensional concept. This helps to understand the concept of what the real-life physical requirements of a project are from a 2D drawing.

However, using a BIM model delivers this information straight away as it automatically calculates quantities. This is a major benefit of using BIM over 2D designs.

Quantity takeoffs are important for understanding the material needs of a project. However, their findings also support other dimensions in construction, such as cost and time. 

Getting a realistic understanding of the materials through BIM will therefore help you to gain a better overview of all dimensions of the project. 

 

Final Thoughts

A quantity takeoff is necessary for understanding the overall scope and budget of a construction project. Through using the right technology and approach, you can gain a realistic understanding of what will be required to achieve the end-results of a project.

BIM can help to improve the accuracy of a quantity takeoff as there are more realistic features involved in these models. You deal with a 3D model that better displays the construction requirements – giving you more accurate data. 

Getting a proper takeoff done will enhance your bidding process, save money, and avoid rework or speed bumps in the construction process to follow. Thus, you need to make sure that you get it right. 

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