The average 30-year mortgage is already up a percentage point since early spring.
The average adjustable-rate mortgage was 8.69 percent, unchanged from the previous week, the agency said.
The average adjustable-rate mortgage rose to 7.82 percent, from 7.79 percent.
The average adjustable-rate mortgage rose to 8.16 percent, from 8.06 percent the previous week, it said.
The latest figures from the building societies suggest that the size of the average new mortgage granted in 1988/9 was £35,000.
The average mortgage outstanding to banks was £29,400.
The rate on the average fixed-rate 30-year mortgage has dipped a little more than half a percentage point.
Last week, the average 30-year fixed-rate mortgage carried a 6.36 percent interest rate, up from 5.77 percent at the end of July.
The current first-year monthly payment on the average adjustable-rate mortgage would be $743.19.
In the last two weeks alone, the average 30-year fixed mortgage has fallen to 7.18 from 7.33 percent.