Job estimating for contractors comprises of reviewing all of the M & E information this includes the tender drawings, tender specification, bills of quantities, schedule of rates and CDM ad health and safety plan. The job includes site visits to survey the existing M & E installation and using this information to asses the overall impact of the existing installation. When job estimating for contractors, the estimating engineer’s job is to compile the information along with the take off straight from the electrical and mechanical drawings. After take off is complete the Estimating Engineer must input the take off into the estimating quantities software.
The contractor estimating work must insure all preliminary items are included into the job to cover the site conditions and restrictions. Sometimes the health and safety plan will detail particular restrictions in the risk assessment sheets which are applicable to the contract.
The contractor then estimates the overall uplift for the job by assessing the risk on capital employed. Although profit on sales is low, often the return on Capital employed R.O.C.E on the job is high due the high gearing created by creditors from specified suppliers and sub-contractors specified. The job for contractors can be made more profitable if alternatives are found during the value engineering phase.
Caution should be taken not to unintentionally accept design liability by putting forward changes to the design. Job estimating for contractors takes experience and requires a person to quickly comprehend new ideas and design. Good understanding of spreadsheets is essential but mechanical cost estimating software is readily available and often free, so should be used to avoid errors. The books on estimating are widely available and illustrate how to calculate overall mark-up for a job and make ideal estimating models.