When estimating concrete reinforcing costs, ascertain that the reinforcing steel supplier has included all accessories, cutting, bending, and allowences for lapping, splicing, and waste. If no lap specifications are given, a good rule of thumb when estimating the amount of reinforcing steel is to add 10% to your quantities for lapping, splices, and waste. Also, 10% waste should be allowed for welded wire fabric.
The unit price items in the subdivision for Reinforcing in Place include the labor to install accessories such as bean and slab bolsters, high chairs, and bar ties and tie wire. The material cost for these accessories is not included; they may be obtained from the Accessories Division.
General Tips for Estimating Concrete
It cannot be stressed enough to carefully check all the plans and specifications. Concrete often appears on drawings other than structural drawings, including mechanical and electrical drawings for equipment pads and grouting requirements on steel drawings. Assuming all concrete requirements are indicated on the structural and architectural drawings can be a costly error.
When estimating quantities of concrete for floor slabs or walls, do not bother to deduct small areas (two square feet or so) unless there are a large number of these areas, as this can take up more estimating time than the areas are worth. Also remember that you will be adding approximately 3% to the total volume for waste, thereby making these small areas even less significant.
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.
Consider drilling anchor bolts into the concrete where design permits to save time, manpower, and materials on layout and templates during the pour.
When estimating the amount of concrete compression testing that will be necessary for a project, figure on a minimum of one test per pour on smaller pours and 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.
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