The average rate on the 30-year fixed mortgage jumped after standing pat for three straight weeks at record lows. But the rate stayed below 4 percent for the 12th straight week, keeping home-buying and refinancing attractive for those who can qualify.

Mortgage buyer Freddie Mac says the rate on the 30-year loan rose to 3.95 percent. That's up from last week's rate of 3.87 percent, the lowest since long-term mortgages began in the 1950s.

The average on the 15-year fixed mortgage rose to 3.19 percent from 3.16 percent. It hit a record low of 3.14 percent three weeks ago.

So far, low rates have done little to help the housing market, which is slowly improving. Few people can qualify for the rates and many who can have already done so.