Concrete quantities are generally taken off in measures of cubic yards, as this is the way the material supply companies charge for it. For estimating concrete quantities, be sure to include:
When estimating structural concrete, pay particular attention to requirements for concrete additives, curing methods and surface treatments. Special consideration for climate conditions as well as hot or cold weather conditions must be included in your estimate. Also include requirements for concrete placing and finishing methods and equipment.
For accurate concrete estimating, the estimator must consider each of the following major components individually: formwork, reinforcing steel, ready-mix concrete, placement of the concrete mix, finishing of the surface, and curing.
Formwork - A primary cost for cast-in-place concrete is forming. Most jobs today are constructed with prefabricated forms. The selection of the forms best suited for the job and the total square feet of forms required for efficient concrete forming and placing are key elements in estimating concrete construction. Enough forms must be available for erection to make efficient use of the concrete placing equipment and crew. read more.
Reinforcing Steel - When estimating the amount of reinforcing steel, either bar or mesh, if no lap specifications are given, add 10% to your quantities for lapping, splices, and waste. read more.
Concrete Placement - When estimating the placement of concrete by direct chute, the forms available generally determine the volume of concrete placed per hour. The more you have available, the more concrete can be placed in the course of a day. When placing concrete by methods involving a bucket and crane, pumping system, conveyor belt system or other mechanical system, set up enough forms to keep the above systems productive for the entire day. Usually the cost for the use of the equipment for a full day will be charged to you even if you only use it for part of a day.
Sequencing the Pour - During the estimating phase of the project, whatever method or sequence you envision for placing concrete should be documented thoroughly. This will allow those in the field to know how you arrived at the estimated costs and which methods they should use (or try to out-do, in terms of cost effectiveness). Another reason for detailed documentation is that during the documentation process, it may become evident that you cannot place the concrete as you planned or that you can do it differently, more efficiently, or at less cost.
Always obtain concrete prices from suppliers near the job site. A volume discount can often be negotiated, depending upon competition in the area. remember to add for waste, particularily for slabs and footings on grade.
When estimating the amount of concrete compression testing that will be necessary for a project, figure on a minimum of one test for each fifty yards of concrete placed. Each test should consist of taking a set of three cylinders minimum.
Read more concrete estimating tips.
2011 Concrete & Masonry Cost Data Book
Contains the latest unit price data, with illustrated concrete and masonry assemblies cost tables, helpful reference data and estimating aids
» Learn more
2011 Building Construction Cost Data Book
Thousands of unit costs for building components, arranged in the new CSI MasterFormat® 2010 classification system
» Learn more