If you can smell mildew in the home, it's a sign of long-term moisture gone unchecked. The smell of mildew and any visible signs of rotting could mean much more significant damage that you can't see, such as mold, which can harm your family's health.

If you can't open some of the windows or if some of the home's doors are tough to open and close, these could be signs of something much bigger. Sticky windows and doors may be signs of moisture, the house settling, or structural shifts — all of which are pretty hefty repairs that could cost thousands of dollars.

Buying a fixer-upper in a nice neighborhood with good nearby schools is a great idea. But if the run-down remodel you've got your eye on is in an area with similar homes, it could be a bad sign. Quality educational institutions may be a lengthy drive away, or your kids could be walking to school through an unfavorable neighborhood. Even if you renovate the home considerably, you can't always remedy the community.

There's nothing worse than walking into a home with the scent of mice or rats. Once rodent infestations get to the point where there's an odor, the chances of forcing these pests to find another home are slim to none, and traps can only go so far. What about an insect infestation, like fleas? This can sometimes be solved with bug bombs and flooring replacement. However, repair costs can be astronomical if the home shows signs of termites or carpenter ants. Removing the pests is one thing—mending the damage they've caused can make a fixer-upper a real downer.

Sloping or sagging floors could be a sign of structural problems. If the floors are distorted due to a damaged subfloor, that's potentially fixable. But, if it’s buckling because the home's frame, foundation, or joists are damaged, you may want to keep looking. You'll also need to factor this additional cost into your renovation budget.

When you visit historic cities like Savannah, Georgia, and Philadelphia, Pennsylvania, it's easy to fall in love with the turn-of-the-century homes on display and perhaps even entertain the idea of one day owning one. While most historic homes have been lovingly restored and receive annual maintenance, owning one comes with caveats. Houses with historic designations and properties in historic districts may have zoning restrictions that impede specific improvements to the house and land. Consider this carefully before you decide to purchase a landmark.

Do you daydream of owning a home so far from the rush of city life that you're willing to pay top dollar for it? The idea of no nearby neighbors is certainly enticing. But before you decide to buy a nearly off-grid project home, it's important to think it through. For instance, where is the closest DIY home store? Material runs could eat up a better part of your day. If you have items shipped to you instead, the shipping costs for an off-grid address could shrink your budget. It can be done if you've figured these costs into the renovation and it won't break the bank.

If you've ever caught an episode of Bros of Decay on YouTube, you know: It's not just homes in forgotten neighborhoods that become weathered and need repairs. Generations pass, and even the most affluent of families can leave magnificent homes behind, including antiques and other belongings. If you've found one of these generational mansions and you can imagine a fabulous lawn underneath the brush or can envision the B&B you could open, you might have your dream home and a money-maker on your hands once you've put in the work.

Getting a home inspection is the only way to know if all the renos are mostly minor cosmetic updates. Often, the greatest issues with a property aren't apparent at first glance. If your inspection highlights a few cosmetic repairs, chances are it's a good investment. But if your inspector shows you a crumbling foundation, old-school electrical wiring, or outdated plumbing, you may want to keep looking.

The easiest way to conserve your finances on a fixer-upper is to do most of the renovations yourself because every job you have to hire a contractor for eats into your bottom line. If there are projects you'll need help on, get estimates before making a hiring (and maybe a buying) decision.