Appendix: Costing and estimating

Costing is the pricing of completed work taking into account not only all the direct expenses— materials, wages and insurances, fuel and power, machining costs, workshop expenses, etc.—but also a fair proportion of the indirect expenses—salaries, office expenses, rent, rates, depreciation, interest on capital, etc.— expressed as a percentage addition to the workshop cost. Estimating is the intelligent anticipation of what the total cost is likely to be, and as such must have a basis of actual costing experience. In other words good estimating is the product of sound judgment and careful appraisal of the amount of labour involved in the proposed work, in the light of past experience of other comparable work.

In costing and estimating for quantity production the work can be broken down into a sequence of bulk operations, and accurately priced by cost accountants and experts in work – study. Where large runs are contemplated, or where a totally new design is to be introduced, a finished prototype will be made by skilled craftsmen, knocked down into its component parts, further simplified or systematized for repetition machining, and then costed either with trial-runs of the individual components or recorded costing of other similar operations. This measure of accuracy, often carried to decimal points per item, is not attainable in hand-production for most of the work will be continually breaking fresh ground, therefore the estimator must rely on his own good judgment, building up as he goes his own personal file of cross-reference. There are, however, certain guiding principles which, while they will not solve his equations for him, will at least suggest a method.


The cost of any piece of woodwork will consist of several factors, each of which must be independently valued. Some, if not all, of these costs are always present in any analysis or build­up, and should be itemized as follows.


Wood, plywoods, veneers, etc.: actual net bulk purchase or replacement cost, whichever is higher, including haulage, stacking, weathering, etc., to which must be added the appropriate wastage factors.

Brasswork, ironmongery, etc.: cost of screws, nails, brasswork, special fittings, etc. at purchase price or replacement value.

Sundry materials: all other miscellaneous materials, including glue, glasspaper, polishing materials, etc., directly chargeable to the work. As it is sometimes difficult to assess the amounts of such items as glue, sanding and polishing materials, etc. consumed in any one job, the total cost over the year is sometimes expressed as a percentage addition, but the system is likely to be unfair to some classes of work, and it is better to itemize wherever possible.

Timber calculations

In calculating the timber content of a cutting list for costing purposes the appropriate wastage factors must be added. Whereas softwood in scantling dimensions may need from only 5 to 10 per cent addition, square-edge hardwoods will require 15 to 20 per cent, and most waney or wane edge boards and planks 60 per cent, with the exception of certain wasteful timbers— walnut, rosewood in the log, etc.—where the true waste factor may be as high as 200 per cent. Plywoods, blockboards, etc. bought carefully to suit the dimensions needed may only require 10 per cent, but an average 20 per cent is safer, while most veneers will need at least 50 per cent. Where there is any doubt it is always better to debit the whole planks, sheets or leaves to the job and credit back the usable surplus, not including rippings and off cuts.

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