Construction estimating is the process of calculating the cost to complete a specific building project. This process is performed by estimators, who may be employed by general construction companies or subcontracting firms. Estimates are usually done as part of the bidding process, where each contractor submits his estimate to the owner in hopes of winning the project.
Review the building plans, specifications and all other project information. Examine each page of the drawings carefully to understand exactly what tasks are involved in the project. Look for any special materials or installations that may add to the cost of the job.
Create a bid sheet that outlines all the tasks that will be performed during the project. For example, a small renovation job may include tasks like painting, drywall, demolition, carpentry and flooring. Larger jobs may involve hundreds of different tasks. Many estimators use the CSI MasterFormat numbering system as a guide when developing a bid sheet. This system will minimize your chances of overlooking certain tasks.
Decide whether you will need pricing from subcontractors. Examine your bid sheet to see which tasks your company will self-perform and which will be contracted out. Send drawings to subcontractors requesting pricing for these tasks. Give these companies plenty of time to prepare their bids or estimates.
Calculate the quantity and cost of the materials required for each task. For example, measure the total square footage of drywall shown on the building plans and multiply this figure by the average cost per square foot in your area. Repeat this process for every task on your bid sheet. For average cost data to help with your estimate, refer to the RS Means Construction Cost Data Book in the Resources section of this article.
Determine the installation and labor costs for each task on your bid sheet. For drywall, you will multiply the total square footage by your average labor cost per square foot. Calculate labor cost per square foot by dividing the hourly wage of your installers by the number of square foot they can install per hour. If each one installs an average of 100 square feet per hour and is paid $10 per hour, the installation cost equals 10/100 or 10 cents per square foot.
Add all of your costs to arrive at your final estimate. Include labor, materials and subcontractor pricing. If there are any additional costs you have not included, be sure to add them as well. This may include things like permits, tools, equipment rental, supervision or overhead. Once you have arrived at your final estimate, add a percentage on top to cover profit.
You can often find up-to-date construction cost data guides in the reference section at your local library.