Much of the house flipping is centered in California, where prices are on the rise by some of the highest amounts. For example, the number of homes sold in California recently that have been bought and resold within six months has reached its highest level since late 2005, according to PropertyRadar research. About 5 percent of all homes in the state have been flipped this year through April, according to the data.

House flipping is different from the housing bubble days. For example, in a tight lending environment, house flippers nowadays are mostly using all-cash transactions for their home purchases. Also, many investors are fixing up foreclosures or neglected homes that other buyers may pass up.

Still, some in the housing industry are concerned that investors are snatching up the limited inventories of homes for sale from other buyers.

Flippers get a “bad rap” in the public eye, says Robert Ganem, who flipped about 20 houses in the last year. “Most buyers want a home that’s move-in ready. We come in and make repairs that a bank or an underwater owner is not going to do.”