Cuts in housing credit and the virtual elimination of construction programs proposed in the 1983 fiscal budget would slam the door on most home-builders who look to federal programs to do business. But opportunity may be knocking for the mobile/manufactured housing industry and, to a lesser extent, for condominium developers.

Although the Reagan administration has called for a $5 billion cut in FHA mortgage insurance programs--from $40 billion down to $35 billion--it also hopes to target those funds for first-time home buyers and inner-city residents. This would be accomplished by enactment of legislation facilitating the sale of smaller, cheaper housing--and thus could be a boon for buyers and sellers of condos, the administration feels.

Firms that manufacture mobile homes and housing components for on-site assembly received a break recently when FHA raised its loan guaranty ceilings for buyers of manufactured housing. Other proposed changes in loan regulations may also benefit mobile-home buyers by encouraging the use of dweller-owned lots.

Some developers and prospective home buyers also were bouyed when the Department of Housing and Urban Development reported plans to raise the ceiling on FHA loan guaranties for condominiums.

FHA loan limits for mobile homes were raised by $2,500 last month to $22,500 on single-section homes and by $5,500 to $35,000 on multi-sectioned homes, while loan repayment periods were increased to 20 and 23 years, respectively. The typical multi-section manufactured home has about 1,500 square feet--about half the space of a large, three- or four-bedroom conventional house--and sells for $30,000 to $40,000. More than a third of all new houses sold in the country last year were manufactured homes, up from 29 percent in 1980, the industry's trade group, the Manufactured Housing Institute, reported.

That increase was seen as a direct result of the 1981 Omnibus Budget Reconciliation Act, which also called for higher limits on the HUD-administered combined mobile home-and-lot loan program. The loan guaranty ceiling on a single-section manufactured home with lot rose to $35,000 (up $7,500), while the limit on a manufactured house built from several sections, commonly called a "double wide," was lifted to $47,000 (up $11,500). The insurable loan limit for a lot rose to $12,500 (up $2,685).

HUD Secretary Samuel R. Pierce Jr. maintains that the changes will reduce the gap between the price of a mobile home and the size of the FHA-insured loan, effectively reducing the down payment.

HUD Undersecretary Donald I. Hovde assured industry representatives at a Louisville trade show last month that manufactured housing "will play an important role in the administration's housing policy, especially because they constitute a free-enterprise solution to the acute problem of housing affordability."

Revised FHA regulations to open the way for government-backed real property loans for mobile homes--as opposed to consumer-type loans--are being cleared within the agency, said Philip Abrams, HUD's deputy federal housing commissioner. Previously, mobile homes were ineligible for such loans because they didn't meet the "minimum property standards"--ceiling heights, width of doors, etc.--set for site-built, single-family housing. "In our judgment," Abrams said, those requirements "were no longer significant."

"The demand for housing is very strong--and we're affordable," said Walter Benning, president of the Manufactured Housing Institute.

The major significance of recent federal action may be the increased use of manufactured houses on dweller-owned lots, said Benning, who said he expects a related rise in demand for larger, multi-section units that are comparable in size and design to many site-built homes.

In addition to the FHA loan limit boosts, the government-chartered Federal National Mortgage Association--the huge secondary market corporation that buys up mortgage loans to stimulate housing lending--reversed its position last August, following a favorable ruling by the Federal Home Loan Bank Board, and began buying mortgages for houses assembled off site. The Veterans Administration and the Government National Mortgage Association also have broadened their policies regarding mobile homes.

Federal condominium loan policies have been changing too, and more changes are being considered. "Condos that were approved for VA loans are now automatically accepted for FHA loans," Abrams said. He noted that legislation set to be introduced this spring would allow government backing for graduated-payment mortgages sought by condominium buyers. In addition, the agency is considering raising the guaranty ceiling on condo mortgage loans, he said.

"We believe that condos are a good source of affordable housing for the middle-income family," Abrams said. While there are still a lot of regulations that don't favor condos or co-ops, they soon will "loosen up," he said.

Nevertheless, one condominium industry observer thinks things look grim. "I don't think the outlook is bright," said George Sebsow, president of the Condominium Development Association.

"I wouldn't start a new condo project today," Sebsow said. "At some future time, when the government wises up" and helps to lower the interest rates, prospective buyers may be able to afford a condo, but right now "they're not buying anything with long-term obligations," he said.

Some observers of the mobile/manufactured housing industry have also expressed doubts. Jack Wynn, editor and publisher of Manufactured Housing Investor newsletter, says the outlook is "languid." Wynn sees inflation, high interest rates, unemployment in the blue-collar sector and zoning restrictions as major problems.

In the Washington area, zoning regulations restrict most mobile homes to only a few areas.

Arlington County and the District forbid mobile homes, though both jurisdictions will consider some forms of manufactured (prefabricated) housing that meet standard building codes.