WASHINGTON » Average U.S. rates for fixed mortgages edged higher this week for the third straight week but remained low by historical standards.

Mortgage buyer Freddie Mac said today that the average for the 30-year loan rose to 4.53 percent from 4.48 percent last week. The average for the 15-year loan increased to 3.55 percent from 3.52 percent.

Mortgage rates peaked in August at 4.6 percent amid expectations the Federal Reserve would reduce its $85 billion a month in bond purchases. The purchases push mortgage and other long-term rates lower. Last month the Fed deemed the economy strong enough for it to reduce the monthly purchases by $10 billion.

Mortgage rates are sharply higher than they were a year ago when the 30-year fixed rate was 3.35 percent and the 15-year was 2.65 percent. That’s contributed to a decline in home sales over the past three months.

Still, the average for the 30-year loan has been below 5 percent for nearly three years, a trend that has made home-buying more affordable.

Separately, the Commerce Department reported today that U.S. construction spending rose in November at the strongest pace in more than four years, driven by solid gains in home construction and commercial projects.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country between Monday and Wednesday each week. The average doesn’t include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for a 30-year mortgage rose to 0.8 point from 0.7 point. The fee for a 15-year loan remained at 0.7 point.

The average rate on a one-year adjustable-rate mortgage was unchanged at 2.56 percent. The fee stayed at 0.5 point.

The average rate on a five-year adjustable mortgage increased to 3.05 percent from 3 percent. The fee was unchanged at 0.4 point.