"To be able to recycle, there has to be a market" for whatever the product is, he says. Flooding the market with crushed concrete, for example, is likely to depress its value. "It depends on how quickly that comes on line," Homrich observes.

The city started a demolition program in 2010, aiming to take down 10,000 vacant buildings by 2013, but a lack of funds held the total to just over 5,000 structures.

Meanwhile, the city teamed up with the state with $10 million in funding to tear down 1,234 derelict buildings near schools. Some 179 were down and another 56 were under contract in 2013.

The city owns about 60,000 parcels of land and about 10% of the estimated 78,000 vacant buildings in its 139-sq-mile limits.

Detroit's new mayor, Mike Duggan (D), will use $16 million in accumulated fire escrow funds to remove burned-out houses that blight neighborhoods.

"We're going to roll through this community, take down those burned houses and start taking those blocks back," he said in his state-of-the-city address.

Centralized Authority

Duggan also is setting up a Land Bank Authority, which would be in charge of all blight-removal work.

The Detroit Land Bank would be the central point for all demolition work in the city, all demolition funds and nuisance-abatement programs, he says.

That comes in conjunction with existing, ongoing programs funded by the state Housing Development Authority, with $52 million in federal money to remove 4,000 to 5,000 houses over 15 months.

The Detroit Housing Commission is looking at demolition of 56 scattered sites in the next year at an estimated cost of $616,000, according to Lyons. The Detroit Blight Authority has plans to raze 67 houses and clear 21 blocks by May 30.