Even when the 15 percent interst rate ceiling on loans in the District becomes permanent, sweeping away the legal problems that virtually halted housing mortgagtes in the past few days, home buyers still will have a hard time coming up with money to buy a house, lenders and real estate brokers said yesterday.

Not the least of those problems is the cost of borrowing, which by itself is expected to force a number of buyers out of the market by making housing too expensive.

"People are going to have to rethink what they can afford because of the differential in interest rates in just the last month," said Bill Stuart of Stuart & Maury Inc., a real estate firm based in the District. In the past month, most mortgage rates in the area have climbed from about 11 percent to about 14 percent -- an increase that would add about $174 to the cost of monthly payments on a $100,000 house, Stuart said.

In addition to the cost of higher interest rates and the time needed for the shock over the rates to wear away, continued tight money will make mortgages harder than usual to find, some lenders said.

"The mortage business ain't," said John Stadler, chairman of National Permanent Savings & Loan, the second largest savings and loan in the city. "We're not making any new mortgages anywhere, with or without the D.C. situation," he said. "We haven't got any money."

Mortgage money in the city had begun drying up before this week's actions by the Federal National Mortagage Association and the Federal Home Loan Mortgage Corp. cirtually halted mortgage financing in the District of Columbia.

Both corporations halted all funding of mortgages in D.C. because of concerns raised by a D.C. Superior Court ruling earlier this month that the city council's continuing enactment of emergency legislation prohibitin condominium conversions.

The city's interst rate ceiling also had been raised twice by emergency legislation before the council acted last month to make the change permanent. While that permanent change was pending, FNMA and the Federal Home Loan Mortgage Corp. (Freddie Mac) concluded that loans made under the emergency legislation may be illegal.

The permanent legislation is expected to take effect within the next week to 10 days if efforts to waive a 30-day Congressional review period for this piece of legislation are successful.

Once that happens, "I think a lot money will be available at 15 percent," said City Council member John Wilson, who favored raising the ceiling instead of eliminating it all together.

"If the rates get much higher than 15 percent, they're going to be out of the reach of a majority of the citizens in this country anyway," said Wilson. "So what's the purpose?"

It's my anticipation that the money would be available," said City Council Chairman Arrington Dixon. "That was the intent of the council."

After a point, the question of how high interest rates might go "becomes academic, because the number of people who can qualify is so small," said Stadler.