As interest rates decline, Americans look for a turnaround in the homebuilding slump that reached new lows last month - and helped dramatize a housing problem of world dimensions.
The immediate challenge is financing, as in Britain, where mortgage rates recently went up and where the building societies have been facing difficulties like their American counterparts, the savings and loan insti-tutions.
But down the road, whether in the industrial or developing world, a less publicized challenge lies in the dwindling of the big three resources required for housing - land, materials, and energy. Thought needs to be given now to assuring the necessary resources when the pent-up demand for housing is increased by such trends as the maturing of America's baby-boom generation and the third world's current flood of young people.
As it is, according to United Nations estimates, construction in third-world cities falls behind demand by four million or five million housing units a year. In the United States the latest figures on overall housing starts show in October the lowest annual rate (857,000) for 15 years. The single-family rate ( 487,000) was 25 percent lower than in September and the lowest in the post-World War II period. Meanwhile, the annual rate of multifamily construction starts increased, apparently in keeping with the current difficulty of affording new one-family houses. At the same time there are reports of leveling or declining home prices. It is calculated that an investment in a home will remain a good one - but not necessarily the impressively inflation-beating one it has been for many in recent years.
On the global scene the question of housing resources must take a prominent place in the North-South discussions following the Cancun summit. Western nations can learn as well as teach. For example, as the Worldwatch Institute's recent paper on housing notes, Singa-pore's housing board has used stockpiling and bulk ordering to prevent bottlenecks and improve people's access to appropriate housing resources. Some Westerners are already looking into adaptation of available ''traditional'' materials such as adobe.
During the 1970s the United States and major European countries had levels of home construction regularly exceeding the needs of growth in population and new households. Adequate levels can be maintained with forethought based on the changing costs and availability of land, energy, and construction materials.
One handle on the high price of land has been provided by an American developer that saves homebuyers almost $200 a month by leasing them the land on which their homes are built. Careful insulation and choice of fuels can save energy over the lifetime of a house to more than compensate for initial extra investment. Plastics and pressed-wood materials are among alternatives to increasingly expensive woods and metals.
Yet there can come a point where quality suffers. The good old two-by-four is smaller than it used to be. Can it get much smaller? To see the unmoving piles in American lumberyards no one would suspect a scarcity of lumber. Yet the US is importing more soft woods than it used to. How far should this trend continue? How far should customary materials be adhered to or innovative ones be substituted?
Such questions should be considered by President Reagan's commission on housing along with the topics such as financing public housing that were recently publicized as part of the commission's interim report. Appropriate means of financing are essential. They will no doubt be refined and elaborated before the commission's final report next year. But the opportunity should not be missed to explore an overall housing policy for the United States, one drawing on the inventive powers of a great nation to show the world how the resources as well as financing for housing can be provided under the challenges of the coming years.