The contract Tina Fullford signed was very clear: The glass in her new windows had a lifetime guarantee against breakage.

Her problems began when a crack appeared on a window pane a few months after the window was installed in her Thornton home.

Not only did Fullford have difficulty getting a response to her concerns from the Littleton-based company that sold and installed the windows, but she also learned that lifetime doesn’t exactly mean what it implies.

“The crack just started small, right from the start, and kept growing,” said Fullford, whose windows were part of an airport noise-mitigation project in Adams County. “I figured I had the lifetime warranty and I was good.”

She wasn’t.

Not only had the owner of the company — Window-Lux of Colorado — sold the business and moved to Florida, but the lifetime assurance she had been given was actually only for five years. A company representative did not return a call for comment.

“How does a lifetime mean only five years?” Fullford asked. “When I heard lifetime, I believed it was my lifetime, or at least my lifetime in this house, and certainly more than six months.”

Most consumers see lifetime warranty to mean one of three things: the owner’s lifetime or the time he or she owns the product; the lifetime of the product itself; or the lifetime of the manufacturer.

There’s also an implied warranty, which is that a product can do what it’s supposed to do and that it can be used for any purpose the seller says it can.

So nail clippers should be able to clip nails, but if a salesperson or product insert says it can be used to file them smooth, it should do that too, or you can return them citing the implied warranty.

It turns out Colorado law doesn’t give a precise meaning to the word “lifetime” when used in a contract, according to Attorney General John Suthers office. In fact, lifetime can mean whatever the individuals peddling the guarantee want it to mean — as long as they tell you.

“A seller is free to limit a lifetime warranty or guarantee as long as he conspicuously discloses what ‘lifetime’ means,” according to Mike Saccone, Suthers’ spokesman.

Some states are a little different. In California, for example, a lifetime warranty has a minimum three-year requirement. And the Federal Trade Commission says a warranty period not clearly defined is deceptive advertising.

Consumer advocate Edgar Dworsky chuckled at how short a lifetime warranty can be in Colorado.

“I’ve never heard of a warranty labeled as lifetime with such a short number of years associated to it,” said Dworsky. “If it’s seven years, it’s a seven- year warranty, not a lifetime.”

That was also news to Brian Hoyl, a 41-year-old Denver resident who in 2007 purchased a new $2.7 million home in Cherry Creek. The home had a number of issues with windows, plumbing and other items that supposedly came with “lifetime” warranties.

“My natural presumption is that lifetime means the life of the product,” said Hoyl, the owner of At The Beach tanning salons. “They’re being sold as a lifetime. Why wouldn’t it be?”

In this case, it turned out to be the lifetime of the builder, who filed for bankruptcy last year as a result of the housing slump, leaving the warranties unenforceable.

Sadly, it absolutely does not matter what the consumer thinks the warranty means. Rarely does it mean the lifetime of the consumer, and the phrase is little more than a casual marketing tool, according to experts.

Chrysler, for instance, offers a lifetime warranty on its vehicles’ powertrain — which actually means the contract is good until the system sputters to a final stop.

Champion windows offers a lifetime warranty on material and installation that’s transferable to a new owner just once — and then lasts for one year.

Many roof shingles offer a lifetime warranty that’s commensurate with the life of the product — such as 30 years — not the house or its occupants.

Sometimes, though, a lifetime guarantee means just that: forever, no matter who it is. Among the more famous are Zippo lighters, Midas mufflers, Cross pens, JanSport backpacks and Fuller brushes. Even Lego Systems will replace a lost part, no questions asked.

Such lifetime backing is also found in Craftsman hand tools, a Sears product line with the simple, clear promise: “If for any reason . . . (it) ever fails . . . return it for . . . free repair or replacement.” Period.

“The brand continues to offer (a lifetime guarantee) because it reinforces the quality and trust that consumers can have that Craftsman is there for them to get their project done with confidence,” said Kris Malkoski, vice president and general manager of the Craftsman brand.

The bottom line: Thoroughly read any lifetime warranty, no matter what you’re told.

“All of the details need to be clear and leave no room for confusion,” said Dale Mingilton, president and chief executive of the Better Business Bureau serving Denver and Boulder. “And ask who will service the warranty should the company go out of business before it expires.”

David Migoya: 303-954-1506 or dmigoya@denverpost.com