Home mortgage rates should fall back after reaching a peak later this year, a leading mortgage banker told a Los Angeles news conference here recently. However, home prices probably will continue to rise because fewer homes will be built in 1979 even though the post-World War II "baby boom" generation has come of house-hunting age.

Robert G. Boucher, president of First Denver Mortgage Co. and incoming president of the Mortgage Bankers Association of America, said the nationwide average home loan rate is expected to peak at 11 percent this year, then come gradually down to 9 1/2 percent to 10 3/4 percent, he said.

In California, however, home loan rates already are coming down from their peak of 11 percent reached by some lenders last fall, said Herbert B. Taker, Santa Ana-based partner of Mason-McDuffie Co., Berkeley, and incoming president of the Southern California Mortgage Bankers' Association.

"There is talk of a 10 1/2 percent rate at some lenders," Tasker said. Meanwhile, the speculative home buying fever has cooled and "the demand in California now is real demand" from buyers who want homes to live in, rather than speculators lining up or taking lottery tickets to buy houses for profitable resale, he said.

"What we're trying to do now is house the World War II baby beeom generation," Boucher said. "To do that, we'll need 2 million new units a year for the next decade."

There were 2.20 million new houses and apartments started in 1978, the Commerce Department reported this week, and builders were still going at a 2.12 million annual rate in December.

The mortgage bankers' group has forecast a 15 percent decline to 1.7 million housing starts this year, however -- "not a bad year, historically," Boucher said, but less than enough to meet the demand. There is no longer an excess of unsold homes hanging over the market as there was the last time home building was cut back in 1974, he added.