It's the magic phrase uttered by almost anyone who's ever considered the cost of home remodeling: "We'll get it back when we sell."

Unless you keep those projects practical, though, you might just be kidding yourself.

For example:

Steel front door: Good.
Master suite addition costing more than the average American home: Bad.

Every year, Remodeling magazine looks at the hottest home upgrades and renovations and calculates just how much owners get back with they sell.

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Upkeep is more popular than upgrades these days, says Sal Alfano, editorial director for Remodeling. These are the projects that often recoup the biggest slice of expenses at resale. But prices and returns do vary regionally, he says.

Ever wonder what brings the lowest return when you plant that "for sale" sign? Think high-dollar, high-end and highly personalized add-ons that make you drool. Like a totally tricked-out garage built from the ground up. Or a super luxe master suite addition. Or the home office redo designed just for you.

Here are the six improvements that, in their 2010 report, ranked dead last nationally when it comes to getting those renovation dollars back at resale.

Home office remodel

Want to get an idea what today's office-away-from-the-office looks like? Walk into Starbucks.

These days, a home office consists of a multiple-choice combination of wireless laptops, smartphones, PDAs and touch-screen tablets. And that worker bee might be toiling anywhere from a home patio or a favorite restaurant to a park bench.

The standard home office renovation, meanwhile -- complete with plenty of built-in storage and high-tech wiring -- is this year's biggest loser in the resale value sweepstakes. Nationally, homeowners spent an average of $28,888 and can expect to recoup about 45.8 percent at resale, according to the report.

Return on investment doesn't reflect your enjoyment of the space, Alfano says.

He offers two tips for home-office remodelers when they sell. First, opt for something that can be easily converted back into a bedroom or den for (or by) the next buyer.

Second, when you're selling, call it a study, den or hobby room. "There's lots of call for multipurpose space. Don't lock yourself into that one use," Alfano says. Don't use words that invoke images of actual work. Or the office.