DEMAND FOR TIMBER PRODUCTS 



159 



walls with consequent savings in the materials 

 used for framing, sheathing and exterior walls. It 

 was assumed in this analysis that proportions of 

 townhouses will continue to increase. 



Prefabrication of structural members such as 

 roof trusses and increased factory fabrication of 

 housing components and units have tended to 

 lower average unit use of some wood products, 

 primarily through reduction of waste and improved 

 design. This trend toward use of prefabricated 

 housing components and some increase in factory 

 fabrication is expected to continue through the 

 projection period, although problems of building 

 codes, consumer tastes, transportation costs, and 

 fragmentation of the building industry may act 

 as constraints on a major shift to industrialized 

 housing. 



In conventional on-site construction, more 

 efficient use of wood, such as wider spacing of 

 studs and other structural members, has tended to 

 bring about somewhat lower use of timber products 

 per unit. There are also opportunities for additional 

 savings in use of materials by changes in design and 

 specifications. 



Materials substitution. — The rising trends in 

 use of plywood and building board per housing 

 unit and the concomitant drop in lumber use has 

 reflected extensive substitution of plywood and 

 building board for lumber in such uses as sheathing 

 and subflooring. For example, between 1959 and 

 1968, average lumber use for sheathing and sub- 

 flooring in single-family houses inspected by FHA 

 declined from 1,667 board feet per unit to 975 

 board feet. 25 



Plywood use for these components in this period 

 rose from an average of 1,314 square feet to 3,086 

 square feet (%-inch basis). 



In addition to such wood-for-wood substitution, 

 wood products have been displaced in a number of 

 applications by metal siding, by plastic trim, and 

 by nonwood flooring materials. Substitution of 

 carpeting for oak flooring has had a particularly 

 marked effect on wood use in apartment construc- 

 tion. 



Metal framing systems — steel and aluminum — 

 have been used in single-family house construction 

 as well as in multifamily structures. Although 

 use of such systems in single-family construction 

 has been quite limited, one recent study concluded 

 that substantial displacement could occur with 

 a 30 to 50 percent increase in relative prices of 

 lumber over the 1970 level. 26 Another study 



25 Phelps, Robert B. Wood products used in single- 

 family houses inspected by the Federal Housing Adminis- 

 tration, 1959, 1962, and 1968. USDA Stat. Bull. 452, 29 p. 

 1970. 



26 Kroll, Seymour and Associates, Inc. A comparative 

 research study of wood and metal framing systems. 

 Western Wood Products Association Report WWP-1, 

 Copy 1. Portland, Oregon. 1971. 



indicated that with 1972 prices of materials and 

 labor, that is, with relative lumber prices 35 

 percent above 1970, lumber retained a slight 

 cost advantage over steel for exterior studs and 

 for floor framing for most builders, but had a 

 substantial disadvantage for interior studs. 27 



Projected timber products use j actors. — The pro- 

 jections of lumber and other timber products 

 used per housing unit shown in table 121 have 

 been based upon a judgment evaluation of the 

 various factors discussed above. 



For the initial projection, with 1970 relative 

 prices of timber products, it was assumed that 

 total use of timber products per square foot of 

 floor area in 1- and 2-family housing, would 

 decline slightly, as shown by the following 

 tabulation : 



Floor 



area Lumber Plywood (square Building board All timber 



(square (board feet, %-inch (square feet, products (board 



Year feet) feet) basis) li-inch basis) feet equivalent) 



1962 1,335 8.38 2.25 0.99 11.30 



1970 1,475 7.35 3.65 1.06 11.54 



1980.. 

 1990. . 

 2000. . 



1,615 

 1,680 

 1,710 



6.60 

 6.25 

 6.00 



Projections 

 3.80 

 3.85 

 3.90 



1.15 

 1.25 

 1.35 



11.01 

 10.80 

 10.69 



Projected lumber use continues to drop while 

 use of plywood and panel products is expected to 

 rise. The projections assume substantial increases 

 in the per unit use of building board in all types 

 of units. Use of particleboard is expected to rise 

 fairly rapidly, with moderate increases in use of 

 hardboard, and a decline in use of insulation 

 board per unit. There may be a much larger rise 

 in the use of particleboard if structural grades 

 are developed which can be substituted for ply- 

 wood in roof sheathing and subflooring. 



Projected Demand for Timber Products in New 

 Housing 



Total consumption of lumber in new residential 

 construction amounted to an estimated 12.3 bil- 

 lion board feet in 1970 (table 122). This was 

 somewhat below the average for the 1962-70 

 period and much below consumption of 19.5 

 billion board feet in 1972. 



The medium projection of lumber demand — 

 derived from the medium projection of demand 

 for housing, the wood use factors shown in table 

 121, and 1970 price relationships — rises substan- 

 tially during the 1970's and early 1980's to more 

 than 18 billion board feet by 1990 (table 122). 



Demand for plywood and building board roughly 

 doubles in the projection period to about 12 

 billion square feet of plywood and 4.4 billion 

 square feet of building board. 



Under the higher price assumptions specified 

 earlier, projected demand for timber products 



27 Koeningshof, Gerald A. Comparative in-place cost 

 between wood and steel residential floor and wall framing. 

 Unpublished. U.S. Forest Serv. Washington. Dec. 1972. 



