Investors backing some of the Triangle's most ambitious residential developments have almost $12 million in unpaid bills -- the latest sign of how a credit crunch is hampering one of the region's biggest industries: building.

Real estate companies owned by Virginia Beach, Va.-based L.M. Sandler & Sons, whose companies have planned thousands of homes at communities such as 12 Oaks in Holly Springs, Amberly in Cary and Renaissance Park in Raleigh, owe contractors for grading, engineering and other work.

The accounting is detailed in almost a dozen liens filed in Wake County. A lien is a monetary claim against a property. Contractors file them to secure payment for completed work. They have 120 days after they finish work to file the lien, which must be settled before or when a property is sold.

The biggest local claim against Sandler's companies comes from Fowler Contracting in Cary. The company is owed at least $5.2 million for grading work at three Triangle communities, court records show.

The developments where Fowler did work -- 12 Oaks, Renaissance Park and Garner's Eagle Ridge -- are managed by a Sandler subsidiary, Wakefield Development in Raleigh.

Executives at Fowler and at Sandler, which claims to be one of the country's biggest private developers of master planned communities, did not immediately return messages seeking comment Friday.

John Myers, Wakefield's president, says Fowler and other contractors will be paid back. It's just a matter of when.

"It's difficult to put a timetable on everything," he said. "This is all an ongoing relationship between the banks and the builders as we work through the communities. The intent is to complete the projects and move forward and have the vendors all get paid."

Developers -- particularly those with residential projects -- are in a tight spot these days.

As home sales have slowed, lenders have become more cautious, which has slowed land sales and made it harder for many developers to pay bills quickly.

That, plus the building slowdown, is putting contractors in a more defensive position.

Lien filings are up nationwide this year.

Two years ago, contractors were less likely to file liens because the hot housing market gave them confidence that they would be paid. Contractors also were reluctant to sour relationships for fear of losing future business. So they waited it out amid the building boom, letting other projects cover expenses.

Because of the volatility in the marketplace, Myers said, "the rules in the industry have changed dramatically and quickly. Everybody's adjusting right now. We're no exception."

Wakefield has spent the past several years doing business like many master developers. It buys big chunks of land -- usually hundreds of acres -- and builds infrastructure such as roads and sewers to support homes. Once finished, Wakefield sells home lots to builders, who then sell individual homes to customers.

Two years ago, the company was more likely to order major infrastructure work for an entire project. It was confident it could pay its bills, based on builders' promises to buy big blocks of lots. Back then, lenders willingly financed a builder's purchase of 50 lots at a time, Myers said.

But as home sales have slowed, those commitments are being winnowed. Now, it's rare for a bank to allow a builder to buy more than 10 lots at a time.

"It has a major ripple effect through our projections and our ability to work through vendors' time lines," Myers said.

Wakefield isn't alone.

Sandler projects in Florida and Virginia managed by other companies owe millions more dollars in taxes and contractor bills, according to The Virginian-Pilot newspaper in Norfolk, Va.