I have used National Estimator for straightforward plumbing, electrical, or carpentry tasks and found it to be fairly accurate. I'm curious if anyone else has used this and foud it accurate. Those building trades are not my primary business, so I have created some spreadsheets to help me estimate.
I provide maintenance, repair, and overhaul services on processing and packaging equipment. This includes mechanical, electrical, and fabrication work. I have spreadsheets with common tasks such as drilling holes, tapping, removing screws, replacing a pushbutton, wiring a plc input, etc. Each task has a time associated with it along with a multiplier. The multiplier is used to adjust for actual conditions such as removing fasteners that are hard to get to or drilling hard materials rather than mild steel. The spreadsheets are a work in progress. I populated the times initially by doing some time and motion studies to get a baseline.
Materials are straightforward. I add a markup and about a 10% contingency depending on the job. Some have very well-defined material needs and some do not.
I don't use the spreadsheets for all jobs. For simple ones, I can estimate the labor reasonably well based on my experience. I have struggled with tracking time granularly enough to assess the accuracy of the spreadsheets. I find I am close on total labor, but I don't know how close I am on individual items.
You mentioned that tracking time granularly enough to validate your estimates has been difficult. If you had a simple system that automatically compared estimated vs. actual time and showed which tasks were consistently under- or over-estimated, would that solve a meaningful problem for you? Or is your current spreadsheet already good enough?
