With the razing of the landmark LaSalle building at the highly strategic southwest corner of Connecticut and L streets NW, almost everyone knows that partners Ted Lerner and Albert (Sonny) Abramson are ready to go ahead with construction of a large office-commercial complex on the huge site that has been acquired in recent years. Their acquisitions already include properties back to 18th Street, with the Esso station plot also nearing Lerner says is the final stage of negotiations. That would give the site a total of 66,000 square feet, mostly on 99-year ground leases. He also said that a ground lease has been worked out for the holdout Italian restaurant site on L Street. "We'll be in the ground by November," Lerner added.

Realtor David Schuchat saw the newspaper photos of the 16-story Carlton House Hotel being razed by a "controlled implosion" and recalled that the building was built by veteran Washington developer Gustave Ring. That 28-year-old Pittsburgh building was a twin of the 1500 Massachusetts Ave. NW apartment building that Ring built here.

How hard-hit are companies building new homes in the Washington area? An Advance Mortgage Corp. market study shows that single-house construction is likely to total 13,000 -- down by 25 percent -- by the end of the year. The report also shows more buyers this summer but fewer "lookers." Strongest sellers are the starter or smaller houses -- the lower-priced single, town and condo apartment dwellings. The unsold inventory? Only 3,000 as compared to 10,000 in 1974, another down period in the new housing market. Over-all, rental occupancy is 96 to 97 percent.

What about those crazy mortgage interest rates that have been yo-yoing up and down and now up again since last fall? The chairman of the Federal National Mortgage Association expects the latest rate upturn to level off this month. In fact, Oakley Hunter told Seattle reporters just a few weeks ago that rates will ease back down to the 11 1/2 to 12 percent range before long and stay there until spring. Now the market rate in this area is over 13 percent.

Long & Foster Real Estate offers a Washington Primer booklet to persons planning a move into the Washington area. Even the 10 basic house styles found hereabouts are displayed in the booklet that can be had for a telephone call to a Long-Foster office . . . The George Hyman Construction Co., based here and one of the nation's major contractors, has a $22.8 million cultural center under construction in Dade County, Fla. Hyman recently completed a $13.5 million library in Atlanta . . . Developer Jeffrey Cohen recently obtained a $4.5 million loan commitment from Washington Federal S & L to put up a new office building at Connecticut Avenue and Hillyer Place NW. That's the site where Cohen had difficulty getting an Irish saloon to vacate last year . . . Town & Country Properties Inc. is one of the firms working to sell the Melrose Castle farm in Casanova, Va. Located east of Warrenton. The 663-acre property is being "offered" for $2.1 million.