By: Charles C. Munroe, III, FCPE, ASPE
An estimate of the cost of construction is one of the critical elements for the success of a project. It is an axiom of estimating that the quality of an estimate is directly proportional to the amount of time spent on its preparation. An estimate prepared in haste simply will not have the integrity of one prepared without the pressure of a deadline. What is a reasonable amount of time to allot to the preparation of a construction cost estimate? Fifty years ago when I first became involved in estimating the usual means of prognosticating the man-hours necessary was simply to heft the roll of drawings and from the weight ‘quesstimate’ the time required. In 1987 I decided there had to be a better method and I sent letters to my fellow members of the American Society of Professional Estimators asking them to maintain a log of the hours they took to prepare an estimate. By 1988 I had received enough data to formulate two means of determining the time required to prepare a construction cost estimate and wrote an article that was published in the Architectural Digest.
The Horse Before the Cart Method
This method requires an estimator to have an idea of what the cost of construction will be either through development of a conceptual estimate, updating an estimate of a similar project or use of a valuation service such as Marshall & Swift. A percentage of the cost of construction is then applied to arrive at the sum of funds to be allocated to estimating. (See the attached chart). This sum then is divided by the hourly rate paid the estimator, or the sum of the hourly rates paid to an estimating staff, to arrive at the total man-hours required. If a bid date has been set then the man-hours are converted to days and worked backward to indicate the date the estimator or estimating staff must receive drawings if the estimate is ready in time. Good practice is to allow extra days for review prior to submitting a bid.
The Sheet Count Method
As the title indicates this method involves counting the drawings that will be used to produce a quantity take-off. Drawings that will not be used or involve only a minimum of time are discounted. Drawings such as the title sheet, index sheet, symbols sheet and to some extent the general information sheets. At the time the article was written the average time spend on each drawing was two hours. Today with the use of digitizers and computer estimating systems the time require is probably no more than one and one half hours per drawing. It is prudent to continue to use two hours per drawing to set a not to exceed time frame. Obviously if a project incorporates repetition of elements the time calculations should take this into consideration and educe accordingly.
A note on selecting an estimator. The American Society of Professional Estimators (ASPE) grants the title Certified Professional Estimator (CPE) to those that enter a study program, pass a General Estimating Knowledge (GKE) test, a Discipline Specific Test (DST) and write 2,600 word article on some aspect of estimating. Both tests are eight hours long and require six months of study. The national office of the ASPE can be reached at:http://www.aspenational.org/
Charles C. Munroe, III, FCPE, ASPE
Is a Fellow & Certified Professional Estimator - American Society of Professional Estimators, Fellow New Jersey Professional Estimator's Association, Construction Cost Estimating Expert Witness and Senior Associate of MPGroup
For more information, please see Mr. Munroe's biography page