Some builders meeting here this week said the worst is finally over in the depressed housing industry--maybe. They fear that a threatened record high federal deficit and a shortage of money available for mortgages may scuttle the industry's modest recovery in its early stages.

Interest rates are down, housing starts and building permits are up, and the economists, bankers, legislators and government officials speaking to the estimated 41,000 people at the National Association of Home Builders (NAHB) convention predicted the upward trend will continue if Congress and the administration hold down the deficit.

The view of NAHB senior economist Michael Sumichrast was representative of the kind of advice builders were getting here: "Let me urge that you approach the year with cautious confidence. Make sure that you do not take unnecessary risks and count on some volatility in interest rates."

Sumichrast, like others, predicted that housing, and possibly automobile sales, will be the only segments of the economy that will improve much this year.

Most of the experts attending the sessions in Houston's giant Astrodome and adjacent Astrohall predicted 1983 housing starts will range between 1.3 and 1.5 million this year. Most said interest rates either have "bottomed out" or will drop slightly before rising again later in the year.

David Maxwell, chairman of the Federal National Mortgage Association, or Fannie Mae, said he expects the interest rates on fixed rate loans to average 12 to 13 percent, and the rate on adjustable rate mortgages to average 10 1/2 to 11 1/2.

The cost of building materials has dropped, and unemployment in the construction industry is expected to fall from a peak of 23 percent in 1981 to 16 or 17 percent this year, Sumichrast said.

In sum, "we expect housing to do about one-third better in 1983 than we did in 1982. Of course that is not much to say since we just ended a year with the lowest level of production since 1946," he added.

Some of the darkest clouds on the home builders' horizon are cast by fears that an adequate supply of mortgage money will not be available.

In a statement issued on the closing day of the convention, the association warned: "The mortgage finance system--once the cornerstone of America's housing policy--is still hanging in limbo after being rocked by shifting government priorities, bank deregulation and unpredictable interest rates."

The banking deregulation act, which allows banks and the endangered savings and loans to offer money market fund savings plans, took effect in mid-December. Since then $140 billion has flowed into the new accounts, 35 percent of it new money that has not been invested in these institutions before, said Sen. Jake Garn (R-Utah), who with Rep. Fernand St Germain (D-R.I.), introduced the legislation in Congress.

Most developers opposed the deregulation bill, while bankers and lenders saw it as a move that will enable the financial institutions to compete with the high-interest money market funds.

Builders felt, as one put it, "we lost a prime source of money and we have not gained another source."

Richard T. Pratt, chairman of the Federal Home Loan Bank Board, said the legislation was necessary to assure the survival of savings institutions, but neither he nor Garn would predict how much home loan money would be supplied in the future by these traditional lenders.

One certainty is that "the world of housing is very different now," said Kent

Other stories from the Home Builders convention appear on Pages E11, E12 and E13. W. Colton, executive vice president of the Federal Home Loan Mortgage Corporation, known as Freddie Mac.

Colton predicted that in the future as much as three-quarters of all home loan money will come from the secondary mortgage market through the efforts of institutions like Freddie Mac. Chartered by Congress in 1970, Freddie Mac supplies money for home loans by buying mortgages from lenders and reselling them to investors in the form of mortgage securities.

Stuart McFarland, executive vice president of Fannie Mae, agreed that much of the mortgage money--he estimated two-thirds--will come from secondary markets. Thrift institutions may continue to make mortgage loans but will sell more of them to the secondary market, he said.

Leaders of the NAHB and several congressmen called for legislation that would open the way for more of the huge sums now in pension funds that could be channeled into housing mortgages.

Private pension funds contain nearly $300 billion, a potentially important source of mortgage funds, said Rep. Ron Wyden (D-Ore.), who, with two other congressmen, introduced legislation in the last Congress that would have removed most of the restrictions that now prevent many pension fund lmanagers from investing in home mortgages.

The bill will be introduced again in the new Congress, he said. Several senators and representatives speaking at the builders' gathering said they favored passage of the legislation.

Congressman St Germain promised to "make housing, community development, and unemployment the highest priorities" in this Congress, and was rewarded by applause by the delegates. He said that "the average worker doubts that the government cares for them anymore. They see a parade of benefits for the richest citizens . . . and workers fear for their jobs and futures."

Seattle developer Harry A. Pryde took office as president of the NAHB, promising to work for reform of local and federal regulations that home builders argue cost them too much time and money.

A Gaithersburg man, David C. Smith, was elected vice president/secretary of the national organization. Smith owns his own company, has been a builder in suburban Virginia and Maryland since 1959.

The convention's theme was "Housing . . . a Priority to preserve the American dream" and throughout the meetings "the American dream" of home ownership was frequently cited, in reverent tones or with patriotic fervor. Many of the homebuilders seemed to see themselves on the barricades, leading the population out of recession and back to their single-family, detached houses in the suburbs.