- Many construction firms don’t allow enough time for estimating, or they rely too much on past experience.
- Making too many assumptions about how a project will go based on similar, past projects is dangerous due to variables like weather, site access, and workforce changes.
- Interruptions, forgetfulness, or mere ignorance might cause you to leave important elements out of an estimate, so that it reflects an inaccurate picture of the projected workflow.
Many construction firms don’t allow enough time for estimating. They pull numbers from the air and hope they can use change orders to make up for shortfalls. Others rely too much on past experience. Those two approaches cause headaches that no estimating method will relieve. However, once you decide to focus on quality estimates in your business, you can achieve greater consistency and accuracy using these strategic estimating methods.
Make no mistake: Past experience is a great start with building new estimates. However, just because a framing crew completed 10 feet of wall in half an hour on one project doesn’t mean you should copy and paste that productivity figure into the next project. Even if the next project has the same scope, materials, and methods, other factors may not necessarily be identical. Productivity changes from one job to the next because:
- Weather is a wildcard
- Site elevations, drainage and soil conditions vary
- Site access is unique
- Labor availability, motivation, health and fatigue factors won’t be the same
- Labor skills and experience levels may change from job to job
When you identify the job-specific factors that may affect productivity, you can eliminate or reduce their effects as you build your estimate. You might add tasks and materials to overcome cold weather challenges when you know you’ll be building during winter. You might increase your labor units on activities with high fatigue factors. If you are aware the site requires light fill across long sections, you might investigate sources that can deliver the fill using belly dumpers.
In all these cases, you are overcoming high probability risk factors by anticipating them and building your response into the estimate. When you don’t assume, your estimating moves from unfounded science to actual art.
If you don’t completely understand how an assembly goes together, you won’t be able to visualize the entire process accurately enough to create a breakdown of the work.
You can reduce your estimating headaches by taking a long view of the project. All design documents are incomplete, if not at a project’s outset, then by midway through construction. You can’t spend your time trying to figure out what changes will occur, but what you can do is study the drawings and look for places where processes weren’t thought through sufficiently or where they are missing requirements needed for completion. Design documents suffer from copy and paste artifacts just like estimates do.
Let’s face it, mistakes also happen.
If your typical wall section in your site plan shows a three-foot-deep foundation footer in an area where four feet is the code, you’ve got to account for that extra work. Some other factor like rigid insulation may allow for a shallower footing, but it’s best to double check. Stay inquisitive so you can stay accurate.
Avoid Logical Errors
As you visualize how to build the portions of a project, you create the work breakdown structure (WBS). If you don’t add each task to the WBS you end up with activities that won’t get finished. Maybe someone interrupted you as you were developing the WBS. Perhaps you merely forgot to include a task. You can guard against these errors by cultivating good work habits like highlighting your place in the estimate whenever you’re interrupted and using assemblies to reduce omission errors.
Simple ignorance might also cause you to omit certain steps of construction. When estimating, you are removed from the work, so you must heavily rely on visualization. If you don’t completely understand how an assembly goes together, you won’t be able to visualize the entire process accurately enough to create a breakdown of the work. Therefore, your plans won’t necessarily provide work sequencing; for example, plans might show that a curtain wall component gets bolted to its support. But they won’t tell you whether you can do that task before you mount the supports to the structure or not.
You can increase your knowledge of unfamiliar methods and materials by talking with manufacturers, watching demonstrations of assemblies on active job sites, and asking others for clarification.
Avoid Assembly Errors
Using assemblies saves time and helps you include all components. There is one serious downside to them, though: They get outdated.
Construction is undergoing a methods and materials revolution. From new forms of concrete and wood to smart plumbing fixtures, manufacturers are flooding the marketplace with new items and new takes on old items. In most cases, these materials have specific methods and specific components you must include with them. If you use an outdated wood frame assembly in place of a laminated wood frame assembly, there’s a lot that won’t be right.
You make many decisions in a vacuum as you estimate. It’s just you, the plans and the specs. There’s no time to confer on every detail. There are three very good reasons to keep notes on specific decisions you make about anything unusual:
- It helps to recall all the places where you need additional information from the design team or from the engineers.
- It helps you remember why and how you arrived at your estimates for the various aspects of the project.
- Your notes explain your estimating decisions to others. They might need to understand how you arrived at your estimates when they deal with claims, insurance, and litigation.