timber products. Over the past decade, roughly half of the 
lumber and two-thirds of the structural panel products, plus 
substantial volumes of nonstructural panel products, have 
been used in the production, upkeep, and improvement of 
housing. About 75 percent of the total timber products used 
in housing over this period went into the construction of 
new housing units. The remaining 25 percent was used for 
upkeep and improvement of existing units. 
Production of new housing in the United States—conven- 
tional units and mobile homes—averaged 1.6 million units 
a year during the 1950’s and 1960’s, moved up to over 2.3 
million units in the early 1970’s, but subsequently dropped 
Table 3.3—Average annual production of new housing units in the 
United States. by type of unit, specified periods, 1950-84, with 
projections to 2030 
Thousand units 
Conventional units 
Total Single- Multi- Mobile 
Period demand Total family family homes 
1950-54 1,692 1,619 1,434 185 73 
1955-59 1,569 1,455 1,260 194 115 
1960-64 1,601 1,470 996 474 131 
1965-69 1,695 1,415 860 554 281 
1970-74 2,342 1,868 1,059 810 474 
1975-79 1,961 1,703 1,227 477 258 
1980-84 1,649 1,391 874 516 259 
Projections 
1985-89 1,997 1,723 1,167 556 247 
1990-94 1,954 1,656 1,156 501 298 
1995-99 2,005 1,688 1,123 565 317 
2000-04 2,176 1,840 1,196 645 336 
2005-09 2,012 1,713 1,118 595 300 
2010-14 2,042 1,733 1,144 589 309 
2015-19 2,062 1,749 1,153 596 313 
2020-24 1,973 1,664 1,094 570 309 
2025-29 1,834 1,529 1,002 527 305 
Note: Data may not add to totals because of rounding. 
Sources: Housing starts: /950—58—Forest Service estimates based on data 
published in U.S. Department of Commerce, Bureau of the Census. Hous- 
ing construction statistics 1989 to 1964. 1966. 1959-84—U.S. Depart- 
ment of Commerce, Bureau of the Census. Housing starts. Cons. Reps. 
Ser. C20. Annual. 
Projections: U.S. Department of Agriculture, Forest Service, based on data 
in Wharton Econometric Forecasting Associates. ‘‘Long-term Alternative 
Scenarios and 25 Year Extension.’’ Vol. 5, No. 1. February 1987. 
92 
sharply in the late 1970’s and early 1980’s (table 3.3, fig. 
3.2). In 1983 and 1984, total output again rose above 2 mil- 
lion units. 
Analyses based on projections of the factors that determine 
longrun demands for new housing units—household forma- 
tions, replacement of units lost from the housing stock, and 
maintenance of an inventory of vacant units—indicate con- 
tinued high levels of demand in the late 1980’s, resulting in 
an average of nearly 2.0 million units for the last half of 
the decade. Housing demand remains at about 2.0 million 
units in the 1990’s, peaks at near 2.2 million early in the 
next century, and subsequently drops to between 2.0 and 2.1 
million through 2020. Over the last 10 years of the projec- 
tion period, total demand gradually declines to about 1.8 
million units. 
The type of housing units demanded—-single-family, multi- 
family, mobile home—is of major importance in projecting 
demands for timber products because of the large differ- 
ences in the average amounts of timber products used in 
each type. 
Single-family houses are typically occupied by households 
whose heads are in the middle age classes, while occupancy 
of units in multifamily buildings and mobile homes is high- 
est among households headed by younger and older persons. 
As a result of prospective shifts in the age distribution of 
the population, and the associated changes in household 
types and income, the numbers of conventional single- 
family units demanded are projected to fluctuate but gener- 
ally remain near 1.1 to 1.2 million through most of the 
projection period. The numbers of multifamily units 
demanded show the same trend. Demand for mobile 
homes—most of which will be produced for primary 
residential use and are expected to become larger and more 
houselike—remains relatively constant at 300,000 to 
340,000 units a year through the projection period. This is 
Just slightly larger than the number of units discarded 
each year. 
In addition to the numbers of new units demanded, their 
size is also an important determinant of the amount of tim- 
-ber products used in housing. The average size of single- 
family housing units, though showing some fluctuation, has 
grown fairly steadily over the past 35 years, rising from 
near 1,150 square feet in the early 1950’s to about 1,825 
square feet in 1986. This increase in floor area has resulted 
in little loss in average lumber use per single-family unit, 
despite a declining trend in use per square foot of floor 
area. The size of units in multifamily structures also 
increased; however, the rise has been somewhat smaller and 
