(FORTUNE Magazine) – With the average price of a first house at $81,000, many Americans feel locked out of the American dream. The percent of annual income that first-time home buyers must fork over for mortgage costs went from 21% in 1978 to 44% in 1986. Corporations, working in housing partnerships and through employee benefit programs, are trying to help out. The activity is greatest in the Northeast and in parts of California, where the scarcity of affordable housing makes it tough to attract and keep employees. Colgate-Palmolive, based in New York City, covers the points an employee pays a bank for the privilege of securing a mortgage. In the New York metropolitan area this can save a buyer about $2,500 on a loan for a modest $250,000 dwelling. This spring the Long Island Housing Partnership (LIHP), a coalition that includes Chase Manhattan Bank, Ernst & Whinney, and more than two dozen other companies and organizations, will break ground for 150 houses in Islip, New York. The group hopes to promote the building of 2,000 units on Long Island over three years for sale to area workers who earn up to $50,000 a year. Restrictions will prevent buyers from realizing windfalls when they resell in the hot Long Island market. Says Rutgers University professor David Schwartz: ''Although LIHP's $420,000 in startup funds is not much more than a company might pay to relocate a handful of senior engineers, the nice thing about multiemployer consortia is that they show each company it's not alone.'' San Francisco's Bridge Housing Corp. has built more than 3,000 units of moderate-income housing in the Bay Area over the past six years. The organization uses the $1.4 million it raised from such corporations as Chevron Oil and Clorox as part of a revolving loan for construction costs. Schwartz calls for Washington to treat housing assistance as a tax- advantaged personnel benefit in flexible spending plans. Senators Alfonse D'Amato (R-New York) and Alan Cranston (D-California) are thinking about putting incentives for corporate housing benefits into their 1988 housing bill.