The East Coast has replaced California as the most expensive real estate market, according to a new survey by the ERA real estate organization.

The poll of ERA brokers found that the average resale price of an East Coast house is now $158,800, compared to $136,100 in the West, $78,100 in the South and $69,500 in the central part of the country. The national average is $111,200. ERA said that six months ago the East Coast average was 3 percent lower than that of the West.

"The high cost of Eastern homes largely can be attributed to the New York and Boston areas, where more and more people, many with top salaries, continue to compete for a limited amount of housing," said Ed Gresham, president and chief executive officer of ERA real estate.

Nationwide, the survey found that on average it takes about 14 weeks to sell a house, two weeks longer than the average six months ago.

The Northern Virginia, suburban Maryland and D.C. building industry associations have given 47 awards in their 29th annual Finest for Family Living competition, which recognizes innovative residential design and excellence in craftsmanship.

Sixty-eight Washington area builders entered 130 of their projects in the contest.

The 27 first-place winners were:

$100,000 or less, attached housing -- Capital Homes Inc. for the Stewart model at the Oakpointe at Laurel Lakes development in Laurel.

$100,000 to $120,000 -- Richmond American for the Coventry model at the Woodland Hills development in Gaithersburg.

$120,000 to $140,000 -- Windson Development Corp. for the Loire model at the Heritage Woods project in Centreville.

$140,000 to $160,000 -- Kettler Forlines Inc. for the Cameron model at the Southern Oaks project in Springfield.

$160,000 to $200,000 -- Miller & Smith Homes for the Laurel model at Arbor Glen in Reston.

$200,000 and over -- Kettler Brothers Inc. for the Logan II model at Hillandale of Georgetown in the District.

$100,000 or less, new condominiums or co-op apartments -- the Christopher Cos. for the July model at the Summer Ridge development in Reston.

$100,000 to $120,000 -- the Milton Co. for the Cambridge II model at Linden at Fair Ridge in Fairfax.

$120,000 to $140,000 -- Detty-Anderson Inc. for model C at the Fountain Court development in Arlington.

$140,000 to $160,000 -- the Milton Co. for the Drake model at the Bentley Place at Penbrooke in Rockville.

$160,000 to $200,000 -- International Developers Inc. for the H model at Montebello in Alexandria.

$200,000 and over -- International Developers Inc. for the J model at the Belvedere in Arlington.

$135,000 or less, single-family homes -- Capital Homes Inc. for the Greenwich model at Aspenwood IV in Columbia.

$135,000 to $160,000 -- Richmond American for the Dartmouth model at Brookside in Gainesville.

$160,000 to $190,000 -- Stanley Halle Communities for the Kenwood model at Red Willow in Bowie.

$190,000 to $230,000 -- Centex Homes for the Kinross model at Chantilly Hamptons in Chantilly.

$230,000 to $300,000 -- Sandy Spring Builders Inc. for the Pennyfield model at Cabin John Park in Bethesda.

$300,000 to $400,000 -- George A. Darne & Sons Inc. for the Raleigh model at Forest Edge in Woodbridge and Wrenn Associates Ltd. for the Corcoran model at Fieldstone in Reston.

$400,000 to 600,000 -- Rocky Gorge Communities Inc. for the Cotswald model at the Gates of Avenel in Potomac.

$600,000 and over -- Vista Group Inc. for the B-1 house at Normandie Farm Estates in Potomac.

$500,000 or less, custom housing -- West Homes Inc. for the Churchill model at Speakers Corners in McLean.

$500,000 to $1 million -- National Development Corp. for the Manor House at Carrwood Estates in Great Falls.

$1 million and over -- National Development Corp. for the Madison model at Ballantrae Farm in McLean.

Special design, planned community -- Ridge Development Corp. for Westridge in Woodbridge.

Special design, rental -- C-I/Mitchell & Best Co. for the Astor model at Tuckerman Station Apartments in Rockville.

Special design, resort homes -- Kettler Brothers Inc./Hidden Valley for the Cedarcrest model at Powder Ridge in Somerset, Pa.

Site/Land Planning -- Kettler Brothers Inc. for Montgomery Village in Gaithersburg.

{More photos of award-winning homes, Page E25.}

IN THE BUSINESS ... Manekin Corp. has started construction on Commons Corporate Center, a 42.5-acre high-tech mixed-use development in Anne Arundel County at the southwestern corner of Baltimore-Washington International Airport. The center eventually will include 320,000 square feet of office, research and development and retail space and a hotel ... Crowell & Baker Construction Co. Inc. and its affiliate, Brighton Commercial Construction Corp., have merged and will carry the Crowell & Baker name ... The advisory council of the Federal National Mortgage Association (Fannie Mae) this week unanimously adopted a report opposing any changes in the company's charter or role in the housing finance system. The group said that Fannie Mae should continue to operate exclusively in the secondary mortgage market and make no change in its relationship with the federal government at this time ... BBI Homes Limited Partnership has started work on 44 garage town houses and a 44-unit condominium building at Kings Gate in Columbia ... The Northern Virginia Board of Realtors is sponsoring a seminar on the latest techniques for new home sales from 9 a.m. to noon Wednesday at the Best Western Inn in Falls Church ... Elaine White, the 1986-87 president of the Montgomery County Board of Realtors, has been chosen as the group's 1987 Realtor of the Year ... Stanley Martin Commercial has started construction on the second phase of the North Lake Medical Park in Germantown ... Long Signature Homes Inc. has started work on a 160-unit Olde Mill condominium project near Woodlawn Plantation in Fairfax County ... North American Housing Corp. has bought two modular housing subsidiaries of the Marley Co. of Kansas City, Continental Homes of Virginia and Continental Homes of New England for an undisclosed sum. Carl Benna, North American's president, said the purchase will make the firm the largest U.S. manufacturer of modular housing with projected annual sales of $80 million. North American Housing has facilities in Point of Rocks, Md., Front Royal and Georgetown, Del. Continental Homes of Virginia is in Boones Mill.

PERSONNEL FILE ... Merrill Lynch Realty has appointed Carole Greenwald as president and Greg Joseph as senior vice president of its Washington company. Greenwald has been regional vice president of the firm's Eastern Montgomery County and Prince George's County offices, while Joseph has been regional manager of the company's Western Montgomery County and D.C. offices ... NewLife Group, a McLean-based residential and commercial developer, has appointed Debra Weiner as vice president for real estate finance. Jeffrey Z. Slavin, once an aide to former D.C. Council member Polly Shackleton, has purchased C.J. O'Shaughnessy Inc., a Rockville-based real estate firm specializing in property management ... William Sargis and Andrew Jones are still, respectively, president and executive vice president of Sargis & Jones, an interior general contracting firm, contrary to a report in last Saturday's Real Estate Notes column. Together with Ronald Bruck they are starting RBA Development Co.