In response to changes in the price of timber products, both 
actual and relative to prices of competing wood and non- 
wood products; improving construction and manufacturing 
technology, building codes, and other institutional factors; 
and changes in consumer preferences and tastes, there have 
been widely divergent trends in the unit-use of the major 
timber products over the past 35 years. For example, in 
housing and other types of light building construction, 
there was extensive displacement of lumber subflooring and 
sheathing by softwood plywood in the 1960’s and early 
1970’s. Lumber use per square foot of floor area in hous- 
ing also was adversely affected by the substitution of car- 
peting for hardwood flooring, and by the increasing use of 
roof trusses and other prefabricated components. Growth 
in the use of softwood plywood, metal, and paperboard 
concrete-forming materials in large buildings and other 
structures, and the substitution of particleboard for lumber 
corestock and plastics for other wood parts in furniture 
manufacture also caused declines in the unit-use of lumber 
in the nonresidential and manufacturing markets. In ship- 
ping, lumber use per pallet also fell, in part because of the 
substitution of other timber products such as plywood, 
hardboard, and particleboard. 
In contrast to the downward trends in the unit-use of lumber, 
use of the other major timber products rose in most of the 
key markets, although, as discussed above, this growth of- 
ten resulted from their substitution for lumber or other tim- 
ber products. The increases in plywood use per square foot 
of floor area in housing and per dollar of expenditures in 
other types of construction, and the rise in particleboard, 
medium-density fiberboard, and hardboard per dollar of 
manufacturing shipments were particularly large in the 
1960’s and 1970’s. More recently, however, softwood ply- 
wood subflooring and roof and wall sheathing have begun 
to be displaced by the relatively newer waferboard and ori- 
ented strand board products. 
In the future, relative prices and the nonprice factors cited 
above will continue to be the primary determinants of 
change in the unit-use of timber products. Accordingly, 
projections of product-use factors for the major markets 
have been based on current trends, judgmentally modified 
to be consistent with the most likely future movements of 
relative prices and associated changes in the various nonprice 
factors. In general, this procedure has resulted in a continua- 
tion of recent trends in the various unit-use factors over the 
next few years. For example, additional increases in the fac- 
tor for oriented strand board/waferboard products in hous- 
ing and other light building construction are projected due 
to their likely continued penetration of traditional softwood 
plywood uses because of price advantages. And, in recog- 
nition of this, the use factor for softwood plywood in these 
markets has been projected to decline. 
For the longer run, the projected rates of increase or 
decrease for the various product unit-use factors have been 
reduced in recognition of the fact that continued change 
becomes more difficult as markets are saturated or as mar- 
ket share approaches zero. This phenomenon, which can 
be due to localized price or to institutional and other 
nonprice factors, has apparently already taken place in the 
case of lumber used for residential sheathing and sub- 
flooring, where there has been nearly a total displacement 
by structural panel products. Since this substitution was one 
of the major reasons for the rapid drop in the lumber use- 
factor for housing during the 1960’s and early 1970’s, only 
a gradual decline due to other causes is likely during the 
projection period. As markets for a particular product be- 
come saturated, any future rises in its total use will depend 
on the development of new markets or increased activity 
in those already established. 
Consumption and Projected Demands for Lumber and 
Panel Products—Based on the projections and assumptions 
about the major markets discussed earlier in this section, 
demands for lumber and the various structural and non- 
structural panel products are projected to follow somewhat 
diverse trends over the next 45 years. In terms of volume, 
the largest increases for lumber are expected to be in 
shipping; for oriented strand board/waferboard, in residen- 
tial construction; and for hardboard and particleboard, in 
In recent years, lumber consumption has 
been nearly a third above the levels of the 
1950’s and 1960’s. Demand for both soft- 
wood and hardwood lumber is expected to 
rise slowly over most of the projection 
period. 
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