Mortgage rates fell slightly once again this week.

The average 30-year fixed rate edged down 3 basis points, to 5.55 percent. A basis point is one-hundredth of a percentage point.

This week's average 15-year fixed rate -- a popular option for refinancing -- fell 4 basis points, to 4.89 percent.

The average jumbo 30-year fixed plunged 16 basis points, to 6.49 percent. The jumbo 30-year has fallen 37 basis points in two weeks.

Adjustable-rate mortgages were split for the third straight week. The one-year adjustable-rate mortgage edged up 1 basis point, to 5.23 percent. The popular 5/1 ARM fell 5 basis points, to 4.93 percent.

Mortgage application activity rose a seasonally adjusted 2.8 percent when compared to a week earlier, according to the Mortgage Bankers Association.

For the week ending July 17, refinancing activity grew 4 percent while applications for new purchase actually edged up 1.3 percent.

In other housing news:

• Housing starts rose 3.6 percent in June compared to the month before, according to the U.S. Commerce Department. It was the biggest rise since December 2004. Meanwhile, applications for building permits rose 8.7 percent.
• Homebuilder confidence rose in July, according to the National Association of Home Builders/Wells Fargo housing market index. July's reading was up 2 points, to 17. An index reading below 50 indicates the number of builders who view sales conditions as poor exceeds the number of builders who believe sales conditions are positive. The index is now at its highest level since September 2008.

To find and compare mortgage rates in your area, visit Bankrate's interactive search tool.

-- Chris Kissell