The median price for a new home will reach $90,000 by 1986 with the average down payment averaging close to $23,000, a Princeton University economist told a Senate committee recently.

Kenneth Rosen said, "The United States is today in the midst of a housing crisis of unprecedented proportion. Most new entrants to the housing market cannot afford to purchase any home at all.

He predicted the prices for new homes will continue to increase faster than the over-all inflation rate. Young families "will be confronted with a major explosion in housing prices and down payment requirements. The situation will become much worse," Rosen told the Senate Banking Committee.

THe median price of a new home will approximately double from the present $45,000 by 1986, he predicted. He said that the inflation rate for new housing is likely to be 10 per cent per year over the next decade, or at least 3 per cent higher than the over-all-inflation rate.

Rosen testified in favor of a bill by Sen. Edward Brooke (R-Mass.), designed to make the purchase of an initial home easier for young families.

Brooke's bill would provide for lower payments in the early years of a mortgage. The bill assumes that families' incomes will rise, making possible higher payments in the later years of a mortgage.

The Brooke biill also would allow creation of tax-exempt savings accounts for home buyers to accumulate funds for down payments.

Brooke and Rosen, who worked with the senator in preparation of the bill, said the legislation is designed to overcome the two main obstacles to home ownership for young families, high monthly payments and increasing down payment requirements.

These developments come as the number of young familise coming onto the housing market is expected to rise. Rosen predicted the number of families entering the housing market will be 31 per cent higher in the next decade than it was in the last decade.

The IHA is patterned after the Individual Retirement Act which permits employess without pension plans to establish their own tax deferre retirement funds. Brooke sees IHA as in aid for the millins of young families that cannot now afford a down payment to realize the "American dream" of home ownership.

Government experts who testifed last week on the bill said it would cost the country $5 billion to $6 billion a year revenues (about as much as as mortage interest tax deduction), and said it would not necessarily add to available mortgage funds. They said it would encourage people to put off home buying, that it would discriminate against renters and divorced couples, and put the government in the position of penalizing those who have to spend their dream home money on medical care, food or some other basic.

The Individual Housing Account is twinned in Brooke's Young Families Housing Act with the graduated payment mortgage (GPM), a system for leveling out the load by upping payments yearly as the homeowner's income increases. The Department of Housing and Urban Development began a test GPM program last fall.

Fragmentary results indicate that younger, lower income borrowers are taking advantage of GPM, said Donne E. Shalala, HUD assistant secretary for policy and researchh. HUD favors expanding GPM nationwide, but 31 states - including the District of Columbia - have usury laws that would prohibit GPMs at the momemt because small early payments result in interest being paid on interest at first.