Rates on 30-year mortgages resumed their decline this week, falling for the 10th time in the past 12 weeks.

Rates on 30-year fixed-rate mortgages averaged 5.57 percent, down from 5.63 percent last week, Freddie Mac said its weekly survey showed. It was the second-lowest level recorded this year.

The decline in rates over the past two months has helped push sales of new and existing homes to record levels this year. The National Association of Realtors reported Thursday that sales of previously owned homes fell 0.7 percent in May after hitting an all-time high in April. However, the May sales pace of 7.13 million units at a seasonally adjusted annual rate was the second-highest level on record.

Despite the fact that the Federal Reserve has been raising short-term interest rates for a year, long-term rates have been falling for much of this year.

For 15-year fixed-rate mortgages, a popular option for refinancing, rates averaged 5.16 percent, down from 5.22 percent last week.

Rates on one-year adjustable-rate mortgages were at 4.23 percent, down from 4.25 percent last week.

For five-year hybrid adjustable-rate mortgages, rates averaged 5.05 percent, down from 5.10 percent last week.

The nationwide averages for mortgage rates do not include add-on fees known as points. The one-year ARM had an average fee of 0.7 point and the other three mortgage categories carried fees of 0.6 point.

A year ago, 30-year loans averaged 6.25 percent, 15-year loans were at 5.64 percent and one-year ARMs averaged 4.13 percent. Freddie Mac does not have historical data on the five-year ARM, which it began tracking this year.

EVENTS . . . The seminar "Green Building Guidelines" is scheduled for 8:30 a.m. to 12:45 p.m. Tuesday at the National Building Museum, 401 F St. NW, Washington. Paul Konove, president of Carolina Country Builders of Chatham County, is to discuss site planning, energy efficiency, environmentally sound building materials and construction waste-management practices. Admission is $130; registration is required. For information, call 202-272-2448; Web site www.nbm.org. . . . Registration has begun for the 2005 Greater Washington Builders Expo, scheduled for Oct. 5 at the Dulles Expo Center in Chantilly. The expo, sponsored by the Northern Virginia Building Industry Association and Maryland-National Capital Building Industry Association, is to include displays and exhibits, four hours of educational programs, lunch and entertainment. Builders, developers and other professionals may learn about the latest products and services. Admission for members of the Washington Metropolitan Sales and Marketing Council is $60 per person until Sept. 23, $75 afterward. Registration and exhibitor forms are available at www.greaterwashingtonbuildersexpo.com. Exhibitors can also call Kathy Rockinberg, manager of programs and events, at 301-445-5401.

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