CHICAGO — Eager to save money, homeowners are more willing to get their hands dirty with home-improvement projects these days. But the DIY route isn't always the safest or cheapest.

"Especially with money being so tight, it's totally understandable that people want to take on projects themselves that in other periods they would have hired someone to do," said Meri-K Appy, president of the Home Safety Council, a Washington nonprofit dedicated to preventing home-related injuries.

But how do you determine if a project entails more than you can realistically handle?

Most people tend to gauge the complexity of a project by doing research online, said Chris Murray, front-end insights manager for tool maker Black & Decker. Some do-it-yourself Web sites grade a project's difficulty.

You also should look at the tools that are required for the job. "If it says 'You need these tools,' do you know how to use them? If you don't, you have a challenge coming," Murray said.

If you're unsure about your ability to finish a project correctly, get an expert opinion before proceeding. Sometimes, you may end up spending more money to repair a bungled DIY job than if you had hired someone to do it from the start.

Here are a few occasions when you may want to consider turning to a pro:

WHEN SAFETY IS AN ISSUE

Tinkering with a home's electric system can be risky business, said Matt Knox, chief executive of DiggersList.com, a construction classifieds Web site. Not only could the do-it-yourselfer risk electrocution, but doing a job incorrectly could create a safety hazard within the home's structure.

A basic ceiling-fan installation is a popular do-it-yourself project. But even that, if done incorrectly, can have dangerous results. More than 19,700 people a year are injured by ceiling fans that are improperly mounted or incorrectly sized, according to Electrical Safety Foundation International, an organization that focuses on electrical safety in the home and the workplace.

Some other jobs that involve safety risks:

Extending a gas line. "Do not mess around with gas. ... If you're DIY, you probably don't know how to check for gas leaks," Knox said. A mistake there could lead to an explosion or carbon-monoxide poisoning.

Projects that involve heights. Carefully assess projects that require you to be high up, whether it's roofing or pruning trees, Appy said. "Do the cost/benefit analysis upfront and ask yourself, 'How well trained am I to do this, do I have the proper tools, what is my physical well being,'" she said.

Projects that require power tools. Obviously, big power tools, such as a circular saw, can lead to serious injury or even death if used improperly. But don't underestimate jobs that could cause an injury that might not be devastating, but would still slow you down, Appy said. "The nail gun that injures the hand you write with, it might not be something that seriously injures you," she said. "But it could be something that puts you out of commission for a couple of weeks."

WHEN WATER IS INVOLVED

Leaks and water damage can lead to more costly and complicated repairs. If left unfixed, they can lead to mold — which affects air quality and if found during an inspection can be a deal breaker on a home sale.

Water-related projects don't have to strictly involve your home's pipes. Putting in a skylight might seem like a do-it-yourself job you can handle. Do it incorrectly, however, and you could end up with a leaky roof, water damage and mold.

"If you're lucky and it leaks, you will see the leak," said Knox. If you're not lucky, leaking can start inside the ceiling and drip behind the walls, causing damage to drywall and wooden beams.

Knox said 90 percent of all construction-defect claims on jobs done by professionals are due to water intrusion, so "it escalates when you go to DIY."

IF THE COSTS OF MATERIALS OR TOOLS ARE HIGH

Sometimes the costs of materials and the expense associated with making a mistake are enough to make hiring an expert a good idea.

"For something like crown molding ... you need an expensive tool and the material itself is expensive," Black & Decker's Murray said. Mistakes on this project are also not always easy to correct, he said.

A kitchen cabinet can cost a couple hundred dollars, and if you order incorrectly, there might be a restocking fee and special orders may be non-returnable, said Mike Albrecht, division director for Home Depot's installation business. Being off on measurements for granite countertops also can be a costly flub.

IF THE PROJECT IS TOO BIG

If you're planning on replacing all the windows in your home or remodeling your kitchen, think twice about how much of the project you want to take on yourself, Albrecht said. Often, you can leave the heavy lifting to the experts, and work on the finishing touches, such as painting and tiling backsplashes, he said.

In a bathroom, for example, you might be comfortable changing lighting fixtures and medicine cabinets, painting and retiling, Knox said.

"If you mess up, there's not injury or damage," he said. "If it can do damage you can't see, have someone else do that part."

While putting in hardwood or laminate flooring can be a good do-it-yourself project, its complexity will largely be determined by its scale: Installing laminate flooring in a small, square bedroom is easy for homeowners to do on their own, Albrecht said. But doing a larger-scale flooring project — involving a transition between rooms or perhaps around a kitchen island — is where people get tripped up.