Solid Wood Products 256 1 



CAPITAL DEPRECIATION ASSOCIATED WITH COMMODITIES 



To extract, manufacture, and transport structural commodities to the building 

 site requires large investments of capital in physical facilities. As these facilities 

 depreciate with use, a dollar amount can be assigned per ton of commodity 

 produced and delivered (table 22-4). For wood-based commodities these 

 amounts (1972 basis) vary from about $10 per ton to nearly $55 per ton, ovendry 

 basis. Capital depreciation assignable per ton of decorative hardwood plywood 

 is $25; that for oak flooring about $33. Of nonwood-based commodities, the 

 greatest capital depreciation is associated with aluminum siding ($53.47/ton), 

 carpet and pad ($114.88), and plastic vapor barrier ($125.33). 



22-2 WOOD AND NONWOOD MATERIALS IN 

 HOUSE CONSTRUCTION^ 



Boyd et al. (1977) analyzed a number of alternative designs for floors, walls, 

 and roofs to determine weights of commodities per 100 square feet of construc- 

 tion. With knowledge of the weight of each commodity in each 100-square-foot 

 section, it was possible to compute (primarily through use of the data in tables 

 22-2, 22-3, and 22-4) the manpower, energy, and capital depreciation require- 

 ments of each design erected in place on the house site. Data on man-hours 

 required to erect the constructions at the house site, while not indicated in table 

 22-3, were obtained from the homebuilding industry and incorporated in the 

 manpower column of table 22-5 (for details, see Boyd et al. 1976). 



Thus table 22-5 compares manpower, energy, and capital depreciation re- 

 quired to build 100-square-foot sections of houses incorporating wood- and 

 nonwood-based materials, including extraction or logging, manufacture, trans- 

 port to house site, and erection. Table 22-5 does not include data on mainte- 

 nance, nor does it include data on heating. All constructions were provided with 

 acceptable (and comparable) levels of insulation, however. 



Substantial differences in energy requirements between alternative construc- 

 tions are evident. In roofs, a design incorporating steel rafters required approxi- 

 mately twice as much energy as wood truss or rafter constructions. Exterior 

 walls sided with brick or constructed of concrete block required seven to eight 

 times the energy of all- wood constructions, and walls framed with metal re- 

 quired approximately twice the energy of counterpart wood-framed construc- 

 tions. In floors, constructions with concrete slabs or with steel supporting 

 members required approximately 10 times more energy than wood floor sys- 

 tems. Manpower and capital costs, however, were in most cases not appreciably 

 different for wood-based and nonwood-based systems. 



