By Joe Stoddard.

Materials take-off modules are now available for the leading computer aided design (CAD) programs. These modules will generate a bill of materials right from a set of plans: a process called CAD-assisted estimating.

Some CAD vendors will tell you the process is simple and seamless. Don't believe them. Making this technology work means adapting your workflow and changing some of your approaches to the design process. Here are five things you should be prepared to do.

1. Modify procedures: A bare-bones drawing may work fine for a sales presentation, but it's too simple to generate a bill of materials. Instead, you'll need planned forks in the road and multiple versions of each drawing. That introduces another layer of complexity to CAD management and version control that for a production home builder can represent a major shift in work processes.

2. Multiply objects: To save time, one-off details are often drawn with lines and shapes. Problem is, the computer has no idea that those tiny boxes you drew represent a custom whirlpool that needs to be taken off and priced. You will need to create and organize libraries of CAD "objects"--countable items and assemblies that mirror real-world options and upgrades.

3. Nix naysayers: If your CAD drafters won't change their ways, the CAD- estimating effort is doomed. So if your CAD guy is spewing all the reasons why he can't change his work methods, or worse, sabotaging drawings to prove that CAD-assisted estimating is a waste of time, it may be time to use the delete button on him.

4. Do the math: The estimator who can quickly spot problems in a spreadsheet may not know how to tweak the CAD program's formulas and functions to correct a take-off quantity. But someone will need to do it. An outside consultant will do at first, but in the long-term, someone on staff needs to develop the expertise. The best candidate will understand the building process and have basic CAD and spreadsheet skills. (If you can create a formula in Excel, you can create a formula in most CAD programs to count something.)

5. Be patient: Don't expect to take-off a 5,000-square-foot custom home with your CAD program right off the bat; instead, start with one component or operation. Many builders start honing their CAD-estimating skills with the foundation. Monolithic materials like concrete require less effort to calculate accurately than, say, a complex framing package.

6. Be realistic: Remember, it's CAD-assisted not CAD-controlled. I've yet to see a CAD-generated estimate that couldn't be made more accurate by a skilled human tweaking the data. Even if you've honed your automated systems to perfection, you still need to build human checkpoints into the process. This could be a simple matter of printing out the estimate and reading it before exporting it to the purchase order system.

Joe Stoddard is a technology consultant to the building industry. You can contact him at