A 10-week course on home maintenance will be offered this fall on the Alexandria campus of Northern Virginia Community College. Topics will include cost savings through energy conservation, using tools -- and when to call repair professionals. For information, call 323-4230.

Ceremonies will be held at 4 p.m. Sunday to mark the opening of Strawbridge Square, a rental subsidy housing development for low-income families in the Lincolnia section of Fairfax County. Named for Robert Strawbridge, a Methodist evangelist in the northern Virginia area late in the 18th century, the housing project of 86 town houses and 42 garden apartments at 5100 Lincoln Ave. was a joint venture of the National Housing Partnership and the Wesley Housing Development Corp.

The Cameron-Brown Co.'s Falls Church office recently arranged $3.2 million in permanent financing for the West Annandale office building being constructed on Rte. 236, near Woodland Road. Scheduled for completion in 1980, the three-story building is being developed by a limited partnership. Frank Montague is the architect.

Pulte Home Corp. has begun building houses in Lake Ridge, a community near Occoquan in Prince William County. Pulte's first venture in Lake Ridge will be town houses priced in the mid-$50,000s. Models will be open later this fall.

Existing home sales across the nation rebounded in July from a June low of 3.5 million units, on a seasonally adjusted basis, to 3.7 million, according to Jack Carlson, executive vice president and chief economist of the National Association of Realtors. He said the biggest resurgence in resales was in the north-central region of the nation. The median price of a resale house rose to $57,900 in July, 17 percent higher than a year earlier.

American University is offering evening courses in home remodeling taught by architect John Reno. For information, call 686-6806.

The area chapter of the Property Management Association will hold a trade show featuring goods and services for professional managers on Oct. 11 at the Capital Centre. For information, call 587-6543.

Area chapters of the National Association of Home Builders will hold a regional trade show from 3 to 10 p.m. Sept. 25 at the Sheraton-Lanham Inn.