How much is your home worth? Better find out before heading to the lender's office or you might end up with a mortgage you can't afford.

The problem stems from the way the industry calculates property values. Loan originators, many paid on commission, sometimes pressure appraisers to fudge their numbers to make mortgages work, experts say. That means people who don't have a ballpark figure in mind before they borrow -- or who don't verify numbers that sound too good to be true -- could be setting themselves up for financial ruin.

"It's an acknowledged problem," says Cameron Rogers, senior vice president of Chicago Title-Market Intelligence Inc. The Hopkinton, Mass., division of Fidelity National Financial Inc.does appraisal work for lenders who outsource that step of the loan process.

"We've had some clients that are very strongly pushing on value. They may have loan processors that if the value's not there, they pick up the phone and say, 'Well, I need $5,000 more,'" he adds. "From a sales standpoint of course, you want to satisfy the applicant's desire because you're more likely going to get that person's business. But are you really doing that applicant a service by pushing it? Maybe not."

Homeowners just want the job done
Many homeowners don't think about how loans get done, just whether they're approved. But one of the most important steps, from both a consumer and lender perspective, is the property appraisal. If a property isn't worth enough to support a loan, that loan won't be made. If the value comes in high enough for a loan but not as high as a borrower expects, the borrower's financing costs will be higher. That's because the appraisal determines the mortgage's loan-to-value ratio and the higher that ratio, the more onerous the loan's terms