What Is a Quantity Takeoff in Construction?
June 21, 2021
Quantity takeoff refers to the process of estimating drawings, plans, materials, etc., to deliver an accurate forecast for construction costs. The quantity takeoff is the first step in arriving at a fully detailed estimate, with the second step being forecasting costs based on the takeoff. The takeoff is a heavily detailed, complicated process within an already complex estimating phase. Without the specifics it supplies, the estimate would be unreliable at best and useless at worst.
Depending on the project, you may hear quantity takeoffs referred to by other names, including construction takeoffs, estimating takeoffs, material takeoffs or estimating, quantity surveying and material counts.
This guide will explore the ins and outs of quantity takeoffs. We delve into the various types of takeoff methods, discuss who is responsible for takeoffs on a construction project, how to conduct a takeoff and much more.
Types of Quantity Takeoff Methods
You can collect the measurements to prepare a takeoff for your estimates in two ways: manually and digitally.
The manual method may be more cost-efficient for smaller companies but often leads to human error and time inefficiencies. On the other hand, the digital approach can expedite the entire process while providing a more detailed estimate.
Let’s delve into each method to see which one may be ideal for you.
Doing a takeoff in this more traditional way means there’s no takeoff tool involved. So, calculations rely on paper blueprints, a scale ruler, a calculator or an Excel spreadsheet with cell formulas.
With accuracy being the primary goal when producing a quantity takeoff, doing this manually requires a lot of skill and considerable time and patience. This would not be the most effective approach for large-scale projects. That’s because time may not be on your side to create an estimate that meets the bid deadline, and there’s ample opportunity for even a tiny measurement error to trigger a much larger problem in your estimate.
Although every piece of lumber and bolt might be carefully accounted for, there’s the genuine risk of miscalculating quantities with a broken spreadsheet formula or an incorrect value being entered. Still, it’s possible to produce an accurate estimate this way. Despite limitations, it’s a familiar method still in use today.
A digital quantity takeoff uses construction estimating software with takeoff capabilities. It was adopted by companies seeking to avoid the inherent pitfalls of the manual approach. Switching takeoffs to a digital method offers much more accuracy and speed in assembling it, with fewer errors.
So how does it work?
This software scans 2D blueprints and imports them as digital versions. From these digital blueprints, tools within the software enable you to capture information about all the materials and their dimensions. And in what may be one of the biggest benefits of this method, the software then takes over all the intricate calculation functions, removing any risk of incorrect data entry or invalid Excel spreadsheet formulas. Some solutions may even pull pricing data from cost libraries available online or uploaded by the contractor or project manager.
These digital capabilities make quantity takeoffs well-suited for large-scale projects, where the precision of measurements and costs are critical and required.
Second Digital Method: (Building Information Modeling)
Considered a subset of the digital method, building information modeling (BMI) is another option to consider. BIM delivers the most precise takeoff to feed a highly detailed estimate. It links data within a 3D model to its associated details, such as dimensions, costs, quantity, etc.
Because these values are already integrated into each material item, they can be pulled and automatically calculated for the takeoff. With this method, the measurement and costing steps are combined into one. The result is the most accurate estimate with the slightest chance of calculation or takeoff errors — and generated in a fraction of the time, which can make a huge difference when up against a looming bid deadline. You can even experiment with material variations within the model and compare how cost variations affect the estimate.
BIM can handle the most complex, substantial projects — from subways to skyscrapers to multi-use facilities — and the energy efficiency and “green” requirements many have. Its use is growing as more companies turn to BIM’s efficiency and precision capabilities.
Who Is Responsible for Quantity Takeoffs?
In theory, everyone involved with the front end of a construction project should conduct quantity takeoffs. However, in practice, this may only sometimes be the case. The project’s overall size will play a significant role in takeoff responsibilities. Since takeoffs are an integral part of the bidding process, every active individual should conduct their own takeoff for complete accuracy. No matter the size of the project, takeoffs should begin by calculating how much the project will cost and how many materials it will take to complete it.
A popular misconception is that architects, engineers and construction managers are the only ones responsible for quantity takeoffs. You may think the specific industry will affect who does takeoffs. However, the industry doesn’t matter nearly as much as the people involved. An estimation is required if any materials are being built at any scale.
Let’s look at who may be responsible for conducting quantity takeoffs for any given construction project:
- General contractors
- Construction managers
- City designers
- Master planners
- Architects (Landscape, tunneling, offshore, etc.)
- Builders and renovators
- Engineers (Transportation, structural, mechanical, etc.)
- Building designers
Quantity takeoffs involve a lot of individuals specializing in various aspects of the project. Communication between all the parties involved is essential to producing an accurate takeoff.
How To Do a Quantity Takeoff
Quantity takeoffs are a complex process that takes time to master. Whether you’re doing takeoffs using the manual or digital method, there have always been two standard parts for producing an accurate takeoff — input and output. Let’s dive further into these parts to see how a precise takeoff is created.
Every quantity takeoff should start by inputting correct information into the plans. No matter your involvement in the project, this part is crucial to producing an accurate takeoff. You’ll want to enter the specifications into your spreadsheet or takeoff software.
The takeoff team can only work with the information provided to them. Generally, the estimator isn’t there to prepare the initial concepts or drawings. Other team members are the ones responsible for design specifications. With that said, a well-trained takeoff professional will quickly identify errors and report them during the data management process.
Material takeoffs are an essential aspect of the output phase. The output turns ideas into physical mockups. That’s why an accurate material estimation is crucial in the previous process. What is created during this process is paramount to winning a bid.
Unlike the last part, where the takeoff team doesn’t have much control, the output stage is where they show their skills. If no errors are present, the material takeoff depends on pinpointing materials, measuring them and incorporating data into the price plan. If completed correctly, you should have an accurate proposal, which will be used to move forward with the project.
Things To Consider When Doing a Quantity Takeoff
Conducting quantity takeoffs predominantly involves mathematical equations. You input the information and play with the numbers to ultimately arrive at the numbers you want. Here are a few things to consider when doing calculations for quantity takeoffs.
- Units: The easiest and one of the most important aspects of a takeoff. Unfortunately, it’s one of the things that gets overlooked the most. When determining a project build, estimators will count things such as lights, pipes, electrical wires. They’ll need to use the total unit figures and multiply that by the unit price to get an accurate unit total.
- Linear length: All combined linear totals will need to be added to determine the proper liner length.
- Cubic volume: This aspect is really important because it gets away from 2D and moves to 3D. You’ll need to calculate use the following formula to determine the proper cubic volume: “length x width x height”
- Surface area: To accurately determine surface area, you’ll need to figure out length and the width. Then, multiply those two numbers together to get a total value.
- Actual weight: Calculating the actual weight of all materials is essential for determining transportation costs.
Despite most takeoff calculations operating with 3D figures, it’s important to remember 2D figures to determine the most accurate takeoff possible.
Maximize Efficiency With Automated Takeoff Software
Quantity takeoffs are a crucial aspect to a successful bid. Understanding the ins and outs of these can help you improve your bid-hit ratio. You may want to approach the takeoff process by using the manual method, but it often leads to inaccuracies. For a more effective approach, we recommend using the digital method.
There’s no room for error when it comes to capital projects. And that’s what InEight Model helps deliver. Our document control software trims the time and effort it takes to perform the highly-detailed quantity takeoffs that form the basis of your estimates. But the Model is capable of much more than that. Learn how it can give you an advantage over a vast majority of the competition — let our team take you through a demo so you can see for yourself.