Before you splurge on that pricey remodeling project, beware: It may not pay you back when it's time to sell.

Considering all the blood, sweat and tears (not to mention money) it takes to make your dream renovation a reality, you'd expect to be handsomely rewarded with a boost in your home's value. Unfortunately, not every remodeling project will bring a handsome return on investment -- and some might even repel future buyers. You might want to think twice about springing for these so-called upgrades.

Over-the-top improvements.
When it comes to renovations, bigger isn't always better. While bringing your post-war bathroom into the 21st century will increase your home's market value, installing a steam shower and carved marble tub probably won't pay off. Before your minor upgrade turns into a home-improvement bender, ask yourself whether potential buyers in your area are likely to pony up for posh upgrades. "People should be careful about over-improving for their neighborhood," advises Stephanie Singer, a spokesperson for the National Association of Realtors. "If you're in a neighborhood with traditional kitchens, and you put in a Viking stove and granite countertops, that's fine. But keep in mind that buyers probably aren't going to value that to the extent that you do." To get the best return on your investment, scour local listings to see what's standard in your area, and then bring your decor up to speed -- but don't leave the Joneses in the dust.

Home office overhauls. 
If you work from home, a designated workspace is a must-have (and a potential tax deduction). But according to a report from Remodeling magazine, overhauling your office won't pay off when you sell your home -- especially if you borrow usable space from a bedroom, living room or garage. Treat yourself to that mahogany desk and built-in bookcase if you'd like, but keep in mind that you'll only earn back about 50 percent of the job cost.

Swimming pools.
Is there anything better than lounging by the pool with a book in one hand and a margarita in the other? Well, it depends on who you ask. "Some people see a swimming pool as a major enhancement. Others might see it as a major headache," Singer says. Your backyard oasis could actually deter those buyers who don't want to deal with skimming, filtering, PH-balancing, heating, repairing and winterizing this high-maintenance amenity. Unless you live in a Southern state where pools are the norm, don't expect to recoup the money -- anywhere from $10,000 to $50,000 -- that you've spent on the big dig.

New roofing. 
Cedar shakes, clay tile or architectural shingles can instantly transform your house, but they probably won't have the same effect on your sale price. After all, buyers think of a roof as a bare necessity -- not a luxury that will inspire them to shell out extra cash. Still, don't put off a much-needed roof repair just because you're worried about the return on investment. If buyers notice a leaky roof or cracked shingles during their home inspection, they're likely to demand a concession for the repairs -- so you may as well fix it now and enjoy it 'til you sell.

Specialized spaces. 
Maybe your recent trip to Tuscany inspired you to convert your basement into a wine cellar. Or you've always dreamed of replacing your boring front door with a working drawbridge. Or your kids convinced you to install a fireman's pole between floors. Whatever your pet project may be, don't expect every potential buyer to share your enthusiasm. "There's a limited audience for that kind of thing," Singer explains. "People just don't see the utility." Quirky renovations can personalize your home (and maybe earn you some bragging rights!) but buyers probably won't be willing to pay a premium for them.

Of course, even if a project won't drive up your home's resale value, that doesn't mean it's a waste of money. "Remodeling a home is a personal decision anyway, so sometimes there are projects you just want to do for yourself," Singer says. "You do have to live in the home; you're not always thinking about resale. Is it a worthwhile project for you? Is it going to increase your enjoyment of the house?" If you're not planning to sell anytime soon, and a new koi pond just screams "home sweet home" to you, go ahead and break out the toolbox.