When a Virginia couple discovered their townhouse was infested with mold it was the start of an arduous, expensive multiyear cleanup. Sanette Tanaka joins Lunch Break with a look at the renovation and how homeowners can protect themselves from the same headache. Photo: Steven Voss for The Wall Street Journal.

Jenny Guinness of McLean, Va., waited as men in moon suits cut away chunks of drywall in 2-foot increments. They would bag and seal the material, and start again. Soon they had removed the walls of an entire room. A mold remediator sat her down and said: “I have really bad news for you. This looks like it goes in every direction…I think you need to have a demolition company come in and start removing whole walls because I can’t see an end to it anywhere.”

In 2008, Ms. Guinness and her husband, Os, discovered that their townhouse in a suburb of Washington was contaminated with stachybotrys—also known as black mold. That launched a painstaking five-year renovation that cost as much as the couple originally paid for the house and involved ripping out walls, replacing many of the finishes and sterilizing nearly every surface and item they owned.

What they couldn’t clean, they threw away, including stuffed animals, sweaters and other items from their son’s childhood that they were saving for his kids. “I remember standing in the snow in the street in a moon suit, throwing these precious things into a bin,” Ms. Guinness says.

Almost every U.S. home has at least a little mold, but roughly 47% of homes have more substantial mold or dampness, says William Fisk, senior scientist at Lawrence Berkeley National Laboratory, who has researched mold for more than 10 years. People who are exposed to mold are 30% to 50% more at risk of asthma, coughing and wheezing, he adds. Mold exposure also has been associated with other health problems, such as bronchitis and respiratory infections.

Mold in homes hasn’t been tracked historically, but certain building practices—like making homes more airtight, installing air-conditioning units and using materials like drywall and oriented strand board, an engineered wood product—have made homes more conducive to mold growth than they were in the past, says Jeffrey May, principal scientist at May Indoor Air Investigations based in Tyngsborough, Mass.

Mr. Guinness, 71, a social scientist and great-great-grandson of Dublin brewer Arthur Guinness, has written or edited more than 30 books on subjects such as religion and politics. Ms. Guinness worked as a Vogue cover model under the name Windsor Elliott. She declines to discuss her age and is currently working on her memoir, tentatively entitled “Faces.” In 1997, right before their son C.J. entered college, the family downsized from a large home on 5 acres to a 3,000-square-foot townhouse in this well-to-do suburb whose residents include Newt Gingrich and Colin Powell.

In 2007, Ms. Guinness was diagnosed with lung cancer. Even after undergoing successful surgery, she still had trouble breathing in the house and, in early 2008, decided to test the home for mold. She discovered that black mold had streaked the firewalls and settled in thick clumps near the floor. The breadth of the mold shocked Ms. Guinness, who says she normally keeps her home spotless. “You could scrape it off with a spoon,” she says.

John Spangenberg, production manager of Columbia Restoration, a fire and water restoration service in Jessup, Md., broke the initial news to Ms. Guinness. He says the McLean townhouse had one of the worst cases of hidden mold he has seen in his 13-year career. “Most of the time when we deal with mold, you can usually find a stopping point. In her situation, the stopping point was after every wall was out,” he says.

The exact cause and time of the initial mold growth is uncertain. Ms. Guinness says her lawyers believe the mold likely began growing when the house was first completed in the late 1980s. The experts found rain streaks on the firewalls, suggesting that the townhouse may have been rained on before the roof and walls were put in, she says.

Virginia is a “buyer beware” state, meaning that homeowners aren’t legally required to disclose a mold problem. Mold can be such a detriment to a home’s value, though, that homeowners are almost always better off paying to remediate or even tearing the house down and starting from scratch, says appraiser Donald Boucher, president of Washington, D.C.-based Boucher & Boucher. Often “it can cost more to renovate a house than it would cost to build it new. You’re better off knocking it down,” he says.

With a townhouse, tearing it down wasn’t an option, the couple says. “The simple fact was, unless we renovated it, we couldn’t sell it,” Mr. Guinness says.

For three years, as the mold was eradicated from their house, Mr. and Ms. Guinness split their time between the U.S. and the U.K., staying with friends while cycling through three remediation companies before finding one they were satisfied with. “We would go to the U.K. and then come back and have to tear out the work,” she says.

As the couple had to assume everything was infested with mold, Ms. Guinness took on the task of deciding which of their belongings to clean and which to throw away. They were able to salvage the wooden furniture and some antiques, but anything made of fabric—all the mattresses, couches, soft furnishings, carpeting, drapes and linens—were thrown out. They replaced the doorknobs, tile, grout, railings and roof as well.

The mold also had penetrated Mr. Guinness’s extensive collection of books. He threw out roughly one-third to one-half of them, many of which were annotated, and the rest have to be hand-cleaned individually by running a vacuum over the spine and sides. Thousands of books are still in storage, Mr. Guinness says.

For Mr. Guinness, the harder sacrifice was having to leave his home for so long. It “was that sense of dislocation and losing our roots, that was the worst thing. We stayed in 15 different homes in the first year,” he says.

People stepped in to help. Several companies gave them contractor or decorator discounts, or lower prices if they bought items off the floor. Neighbors and friends offered places to stay and general assistance. To Ms. Guinness’s knowledge, none of her neighbors experienced any problems with their health or home. “We could never have made it without them,” she says.

The total renovation cost $478,500, as much as the house itself, which was $479,000, according to public records. Ms. Guinness estimates that they spent $107,000 just on getting rid of the mold alone: $17,000 on testing, $70,000 on remediation and $20,000 on cleaning. Since their insurance doesn’t cover mold, the couple paid for the renovation themselves with their retirement savings.

“We read about people who did mold lawsuits and how many lawyers you had to go through and how many experts to go through,” Ms. Guinness says. “We just didn’t think we could face this. We were already fighting something.” Generally, mold isn’t covered under most homeowners insurance policies because it’s considered to be a maintenance issue, says a spokesperson for the Insurance Information Institute.

In January 2012, Ms. Guinness decided to stay in the U.S. full-time to oversee the rest of the work on her home. After the mold was removed, the majority of walls had to be rebuilt from the studs and painted. Some rooms got a more drastic overhaul, with new flooring, doors and countertops. Drawing from her experience as a real-estate agent for 10 years, she served as her own general contractor and interior designer. She hired a plumber, electrician, painter, carpenter and general help. “This has been a full-time job,” she says. “I couldn’t have done it without the Lord sustaining me.”

The result: a brighter, more spacious, three-bedroom, 3½-bathroom townhouse that is, in many ways, an improvement over the former space.

The former kitchen had dark wood cabinets and laminate counters. Ms. Guinness went with a French country-style kitchen with nickel faucets, oak floors and marble counters. The bathrooms used to have builder-grade cherry cabinetry, laminate counters and cream-colored tile. She replaced them with stone, marble and various hardwoods. She also made small structural adjustments to the home, including raising the ceilings in the guest room and study.

Ms. Guinness says she now has no problems with the air. She also believes their ordeal can only help their home’s value. She installed a Swiss-made IQAir air-filtration system for roughly $20,000, the same system used by some Hong Kong hospitals in their fight against SARS. “I honestly feel like this house is the safest house in Virginia,” she says.

Still, the home isn’t complete. Furniture needs to be ordered; artwork must be hung. They still have more than 30 boxes in storage to sift through—not to mention thousands and thousands of books.

“It has been such chaos and one urgent priority after another,” Mr. Guinness says. “I’m looking forward to just being normal.”

The above mold article is being shared by Envirocare Air Quality Restoration, a New York, New Jersey and Connecticut Mold Removal Specialist.  The original version appeared in the Wall Street Journal.