NEW YORK (CNNMoney.com) - A driveway dispute, a fence in the wrong yard, a gunfight ... time to call in a surveyor.

A surveyor draws a map that shows the property limits as well as where the house, garage, and other features, such as boundary fences or walls, driveways and barns and sheds, are located. It also reveals easements such as power poles, sewer manholes, catch basins, drainage ditches, telephone and cable TV boxes. This information is especially important when the homeowner or a neighbor undertakes to build any improvements.

Tom Hagensee, spokesman for the Illinois Professional Land Surveyors Association, says expensive law suits can arise over inconsequential property disagreements.

He had a case in which a Western Springs, Illinois man sued his neighbor over nine inches of property. The target of the suit had a driveway that came right up to the lot line of the suing party and when the driveway owner left his car he would always step on the guy's grass.

"The nine inches and the stepping on the grass didn't start the argument," says Hagensee "but that's where it went."

Randall Myers, president elect of the Pennsylvania Society of Land Surveyors, whose territory includes parts of four states in and around western Pennsylvania, can top that one. "We have some real Hatfield-McCoy type feuds," he says. "In Fayette County, two brothers lived side-by-side for years before one had a daughter who wanted to go to college. He applied for a loan and the bank required a survey, which found his pins (metal-rod boundary markers) were six inches over on the other brother's lot. They argued and one brother shot and killed the other over it."

Myers has handled many disputes between family members. "Just yesterday, some guys tried to run us over with their car. They're in a dispute with their sister over the lot line and had laid railroad ties over her driveway to block her access. Her lot was on property that had been split off from theirs many years before."

It can be vital to update surveys before undertaking a project.

Curt Sumner, executive director of the American Congress on Surveying and Mapping, says a homeowner called him recently because she had a fence put up in the wrong place and wanted to sue her surveyor. The woman claimed the fence company used a survey she had done several years earlier and still wound up several feet on the wrong side of her neighbor's yard. Obviously, the survey was incorrect.

Sumner, however, determined that the builders had taken measurements from the back of the house, which the surveyor mapped as being a certain distance from the rear plot line.

"What the fence builders didn't know," says Sumner, "was that the house had an addition built on after the survey had been done." Oops.

Surveying can be a risky business. Many property owners react angrily just seeing a surveyor. They think it means a neighbor is subdividing or putting in a strip mall or something. But where surveyors can really get into trouble is when they step into the middle of a dispute that goes way beyond disagreements over a few feet of property and involves much more personal animosity.

"I've had to take guns away from people," says Myers. "I've been shot at." Neighbors kill other people's pets or farm animals, destroy fences and rip up yards.

The cost of avoiding some of this by having a survey done is not prohibitive. Sumner says they usually cost between $500 and $1,500 although bigger jobs may run higher.

It can be money well spent.

Sumner himself had a problem on land he owns in Virginia. The people behind him subdivided their land and a crew came in to put in a septic system. "Trees on my side were getting knocked down and the ground tore up," he says. He had to show them an accurate survey of his land to get them to stop.

With property values so high, knowing just where your land begins and ends is more important than ever. People employ surveyors to get a precise map of their lot and lenders and title insurers often require home buyers to survey a property being purchased before they close on it.

"Somebody buying a house would want to know about any problems before they buy," says Sumner. "But for years the number of surveys done kept shrinking."

"Historically, a survey would be done to make title insurers feel more secure," he says. "Insurers, however, found that the incidence of paying off claims has been very low so they've been taking some of that risk."

Now, some title insurers seem to be going back to the requirement.

Adding to the trend, according to Sumner, is that the average lot size is shrinking, even as the average home size ballooned. "People are building 6,000 square foot homes on 8,000 square foot lots. Tolerances are so tight that owners have to be more careful than in the past."

Part of that is new government regulations, according to Myers. Rules and laws dictate location and distance wells must be in relation to septic systems, for example, much more so than in the past. There are regulations about where decks or additions have to end and where utilities can place sewer pipes, electrical conduits and power lines. Many communities dictate how far a swimming pool has to be located away from the lot line.

If the swimming pool gets built in the wrong place, it could cost a fortune to correct the problem.

It's preferable to spend the $500 for a new survey if you have any doubt about where your property limits are.

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