As more neighbors face the problem of a vacant house on the block, an increasing number are joining together to buy up troubled properties.

Housing research group PolicyLink couldn't find any solid numbers, but they say such purchases are happening a fair amount and are usually good for a community.

Cooperating neighbors can have trouble getting a mortgage because these consortiums of private investors usually don't have enough money for a substantial downpayment, says Kate Wilson of Fairway Independent Mortgage Corp.

And Kris Nelson, director of neighborhood programs for the Center for Urban and Regional Affairs at the University of Minnesota, says it takes more than good intentions to make a cooperative purchase work. Buyers need to be clear about what they're committing themselves to, he said. What happens when the property needs a new roof or expensive repairs?