Derek K. Yonai [letters, Oct. 18] argues that rent control, because it prevents owners from charging market rents, inhibits production of new housing. He also writes that restrictive zoning may drive up the cost of land and thus housing. I disagree with the idea that these are the primary causes of the shortage of affordable housing.

To begin with, most U.S. jurisdictions don't have rent control, and many that had it abolished it in recent years. Even the District, which has rent control, doesn't apply it to new construction.

Further, although less-restrictive zoning could help reduce land costs, it would not produce affordable housing on its own. Even an abolition of zoning laws probably would provide only a modest improvement in housing affordability.

The real reason that little affordable housing is built is that rents or sales prices that would be affordable to poorer families are not sufficient to cover the land, construction and administrative costs of developing decent housing. Particularly when the economy is as strong as it has been -- making the demand for higher-margin, higher-priced housing robust -- developers have few reasons to try to build low-cost, low-priced projects.

The cost problem can be solved. We can increase the funds that low-income families can expend on housing either by increasing their incomes or through subsidies such as Section 8 vouchers. Or we can substantially reduce the costs to develop housing. Although existing programs such as the Low-Income Housing Tax Credit and HOME Investment Partnerships Program have generally been successful, alone they often are not sufficient to create housing that is affordable to households with very low incomes.

NATHANIEL TASSLER

Washington

The writer is a consultant who works with developers building affordable housing.