by Staci Giordullo

Angie's List members Lisa and Greg Fennewald thought they did their due diligence by having a home inspection done on their 2-year-old home outside Salt Lake City before buying. When nothing out of the ordinary materialized, the couple made themselves at home.

A few days later, Lisa had trouble igniting the water heater's pilot light, so she called Dave Passey Plumbing & Heating. Passey discovered the pilots needed to be replaced and something much more troubling: no exhaust flue.

"I'd like to think it was an honest mistake, but I was angry it wasn't caught during inspection," Lisa says. "If Dave hadn't alerted us, carbon monoxide would have been leaking into our home. He very well could have saved our lives!"

Unanticipated problems with any house are bound to arise, but what happens when faulty work causes problems that are severe enough to warrant concern for the homeowners' health or cause major depreciation of a home's value?

A number of highly rated service providers alerted us to the more common and critical issues they find as a result of faulty work.

Potential electrical problems

A healthy fear of potential electrical problems is normal — and for good reason. "By hiring a shoddy electrician, you can lose everything and people can die," says Matt Mueller of Trinity Electric LLC in Snohomish, Wash.

"Think of electricity as a dangerous beast and the electrical system is the cage. If there's a weak spot anywhere in that cage, the beast can escape and really hurt someone."

After having a new A/C installed in his Portland, Ore., home, Tim Askin says even his untrained eye could see something was amiss with the breaker box.

"I hired an electrician who discovered several problems, including that it wasn't up to code," he says. "I was worried the faulty wiring could cause a fire."

Poor wire connections, overloaded circuits, improper grounding and broken safety elements on an electrical panel are just a few of the problems that can arise from bad workmanship.

"Shortcuts are taken when people don't know the correct way to do the work or when it's located in a place where nobody will see it, like an attic or crawl space," says Mitch Stewart, owner of Mitch Stewart Electric in Bexley, Ohio. "Homeowners need to be careful who they hire."

Trouble in basements and crawl spaces

Basements and crawl spaces typically include ductwork, furnaces, water heaters and sump pumps — components that can be the most troubling for homeowners.

Tony Mongeluzi, owner of East Coast Comfort in Philadelphia, says he's disturbed by other HVAC companies' poor work.

"I see it all the time," he says. "Systems where the heater was blowing fumes right into a house. In the worst cases, improper venting of the equipment can cause carbon monoxide poisoning and gas leaks which could result in a fire or explosion."

Moisture is another concern. "The biggest problem we see are water leaks," says Bill Richardson, president of the American Society of Home Inspectors. "A little drip can lead to mold, mildew and all sorts of health problems."

Leaks can happen for a number of reasons, including improperly insulated pipes, incorrectly installed seals, and pipes connected using dissimilar metals that cause corrosion.

Unwanted moisture is often attributed to cracks in the foundation resulting from cheaper construction materials, improper drainage around the home's exterior, and poorly located or inadequate sump pumps.

Member Teddi Edington of Renton, Wash., says she hired a team of professionals to remove rodent-fouled insulation, seal ductwork and install a vapor barrier in her home's crawl space after the previous owners failed to have it properly sealed and waterproofed.

"When you can hear the rats partying at night, you know it's pretty bad," she says. "I didn't want my husband to have to crawl around down there."

No matter how undesirable the location, it's a homeowner's responsibility to keep an eye on things.

"People rarely go into their crawl spaces," says Nick Bahnweg, owner of TwoHandymanGuys.com in Charlotte, N.C. "And if they see mold, they tend to think 'Well, as long as it's in there, I'm not going to worry about it.' But your ductwork goes through those spaces, sucks in the air and then pumps it through your house."

Bad plumbing could be deadly

What do a bathroom, garage and fireplace have in common? If not designed properly, they could kill you. "Plumbers are responsible for keeping the public safe," says Vincent Forsythe, owner of Forsythe Plumbing and Heating in Newton, Mass.

"When the work is compromised, there's risk for a myriad of problems to occur — ranging from sicknesses due to airborne contaminants, carbon monoxide poisoning, to explosions and fires."

Forsythe says he runs into shoddy plumbing installations all the time, but the worst he's ever seen involved the installation of corrugated stainless steel tubing (CSST) in a customer's home.

"It made me cringe," he says of the tubing used to carry natural gas that requires very specific installation procedures. "The piping was twisted at the bends into kinks and there were no striker plates. It was a recipe for disaster."

If lightning strikes a home that contains improperly grounded CSST, it can ignite the gas inside the line.

The way in which air flows throughout the home is also important, but often overlooked. Ensuring proper ventilation of gas heating appliances and fireplaces is vital to prevent potentially deadly pollution from entering your home.

"A house is a very connected system and there are consequences to any changes you make," says Tim Hayes, owner of The Hayes Co. in Kansas City, Mo. "The most serious thing we deal with is when the furnace is connected to the garage. If the garage isn't properly sealed, you could backdraft your furnace and water heater. The house will literally suck in the toxic fumes from your garage."

Hayes recommends homeowners perform an energy audit or hire an indoor air specialist to flush out any potential air flow problems.

Danger in attics and roofs

Hidden hazards in the attic and roof often stay that way due to their inaccessibility. A number of highly rated home inspectors say they often find issues with work related to roofing jobs and siding replacement. The most common is the lack of attention to the flashing detail — the material designed to prevent rain infiltration at key intersections in the roofing and siding.

Dustin and Piper Chilson, owners of Magnum Roofing in Pearland, Texas, say nearly 70 percent of their work involves fixing another company's mistakes.

"We see severely rotted wood, soaked attic insulation and mold," Dustin says. Piper adds that many roofers take a number of shortcuts to save money, much to the detriment of the homeowner.

"One lady called us because her new roof wasn't passing inspection," she says. "The guy she'd hired used a stapler to install it. It was so pathetic."

In properties with shared structural elements such as condominiums, there is the additional safety precaution of mandatory firewalls between units. Angie's List member Chuck Marshall of Houston was surprised to find the condo he just purchased had gaps in the firewall.

"Part of the damage to the firewall was due to Hurricane Ike and subsequent roof repairs," he says. "But there are other breaches that are the result of workers who were careless or unqualified."

Deficient deck construction

Outdoor living spaces play an integral part in our lives whether it be for relaxing or entertaining, and these areas should garner as much attention when it comes to safety.

"It literally frightens me to see the vast number of improperly built decks out there and the risk of harm that people are totally ignorant of," says Bob Mulloy, president of Allsafe Home Inspection Service Inc. in East Bridgewater, Mass. "There's a mentality anyone can build a deck."

Deficiencies in deck construction include improper anchoring and attachment, to name a few. Member Dale Berkowitz of Sarasota, Fla., was concerned for her safety and her house's structural integrity after she hired a handyman to enlarge her deck and install French doors.

"He ran the wood the wrong way and it didn't fit against the house quite right," says Berkowitz, who added that the area around the door wasn't framed properly. "The whole ceiling could have fallen on my head!"

Poor drainage around the perimeter of a house is yet another problem that can arise. "Water being where it shouldn't be will cause trouble," says Dave Vollman, owner of Concrete Lifting USA in Fort Mitchell, Ky.

"It can cause concrete slabs to settle, which encourages water to drain toward your foundation, leading to basements that can become wet, moldy and potentially flood during a heavy rain."

Vollman recommends sealing seams in driveways and patios in addition to checking gutters and downspouts. "You want to do everything you can to make the water run away from your house," he says. "It will save you thousands of dollars and headaches down the road."

So what else can a homeowner do to protect themselves? If you're building or remodeling, hire a qualified home inspector to check the work's progress.

"Have it inspected before the drywall goes up," says Bob Sisson of Inspections by Bob in Gaithersburg, Md. "Drywall can hide a lot of substandard work."

For those moving into a new home, inspection is important, but not infallible. "You're trying to balance cost and time," says Richard Harmon, owner of RMH & Associates LLC in Hilliard, Ohio. "You only have the luxury of seeing a home for a few hours, and there's a lot riding on that. It's not a perfect process, but it's a darn good one."

In all instances, do your research before you hire and ask lots of questions. "You can tell who's done their homework," Harmon says. "You can never know too much about what's going on in your house."