How Does a Quantity Takeoff Feed a Fully Detailed Estimate?
June 21, 2021
As all estimating professionals know, it’s the details that can mean the difference between an accurate, realistic estimate or one leading to budget overruns that can cost you more than just your profit margin.
Though a quantity takeoff is only one of the items an estimate needs to achieve the level of accuracy required, it’s perhaps the most important one. The takeoff itself is a heavily detailed, complicated process within an already complex estimating phase. Without the specifics it supplies, the estimate would be unreliable at best, useless at worst. A quantity takeoff is the first step in arriving at a fully detailed estimate, with the second step being forecasting costs based on the takeoff.
This type of takeoff determines how much of each material item is necessary to complete the project. It spells out the particulars about each item (such as the type of lumber, glass, etc.), and accounts for “net in place” calculations. These net calculations are derived from the exact length, width and height (or depth) dimensions on the blueprints and drawings, and also within BIM. No excess is included for waste or scrap. Rather, this “gross” figure is often added as a separate item to cost out during the estimating process, or in a materials takeoff. Why? Because if it were included, it would actually throw off the estimate accuracy that comes from a true quantity takeoff.
Once measurements and quantities are taken, the next step is assigning costs to each item and inputting them into the estimate. These costs can come from your own database sourced from prior projects, third-party industry pricing resources, and/or vendor-supplied pricing. The accuracy of this second step depends on the accuracy of the first step. Not only will it be used for the final bid and to purchase materials, but it will play a role in determining a contractor’s profit margin.
There are two ways you can collect the measurements to prepare a takeoff for your estimates: manually and digitally.
Doing a takeoff in this more traditional way means there’s no takeoff software involved. So calculations rely on paper blueprints, a scale ruler, and a calculator (or the one on your smartphone) or more likely the ubiquitous Excel® spreadsheet with cell formulas.
With accuracy being the main goal when producing a quantity takeoff, doing this manually requires a lot of skill, as well as considerable time and patience. This would not be the most effective approach for large-scale projects — where time may not be on your side to create an estimate that meets the bid deadline, and where there’s ample opportunity for even a small measurement error to trigger a much larger problem in your estimate. Though every piece of lumber and bolt might be carefully accounted for, there’s the very real 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 that is still in use today.
A digital quantity takeoff uses construction estimating software with takeoff capabilities. Adopted by companies seeking to avoid the inherent pitfalls of the manual approach, going digital offers much more accuracy and speed in assembling the takeoff, with far 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 be able to pull pricing data from cost libraries available either online or uploaded by the contractor or project manager. These digital capabilities are what makes quantity takeoffs so well-suited for large-scale projects, where precision of measurements and costs are not just critical but required.
A second digital method
Considered a subset of the digital method, building information modeling (BIM) is another option to look into. It delivers the most precise takeoff to feed a highly detailed estimate. BIM is a process of linking 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 least 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 has the ability to handle the most complex, substantial projects — from subways to skyscrapers to multi-use facilities — as well as the energy efficiency and “green” requirements many have. Its use is growing as more companies turn to the efficiency and precision capabilities BIM offers.
There’s no room for error when it comes to capital projects. And that’s what InEight Model helps deliver. Our BIM modeling software trims the time and effort it takes to perform the highly-detailed quantity takeoffs that form the basis of your estimates. But 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.