Before you hire a professional to inspect a house you might want to buy, there are clues about serious problems you could identify on your own during an initial showing. Spotting these warning signs can save both time and money in your home-hunting process. Here are some of the signs you could spot…

Iffy electrical. Turn on every light and as many appliances as possible at the same time—run the dryer, washing machine, microwave and air-conditioning. If a circuit breaker trips or the lights flicker, that could suggest that the home’s electrical system will need an upgrade, which could cost thousands of dollars. A home’s electrical system should be able to handle all of these installed devices at once. That said, a circuit breaker might be tripped even in a home with a modern, well-­designed electrical system if multiple ­electricity-hungry items, such as hair dryers, are plugged in and run on the same circuit at the same time. 

Also: Take note of any extension cords used within the house. If an extension cord is used to provide power to a part of the home that has unused outlets, those unused outlets might not be working ­properly. If you’re willing to spend $10 to $20, you can buy a small GFCI outlet tester in a hardware store or online that plugs into outlets and confirms that they’re functioning properly. If extension cords extend to areas in the house that don’t have outlets, it’s a tip-off that the home doesn’t have an extensive modern electrical system.  

Mismatched roofing. If sections of shingles are a slightly different shade than the rest of the roof, that indicates the roof required work at some point—which could mean there’s water damage or mold below. Don’t rule out a home just because it has had roof work—the roof problem might have been identified and fixed promptly and properly. But examine the spot underneath the roof repair very closely before making an offer on the home. That might require heading to the attic with a powerful flashlight, something few buyers do. Look and sniff for mold. 

Also: If the home is in a development where most homes appear to have been built at some point during the past 15 to 40 years at roughly the same time and by the same contractor, take a look at the roofs of other homes in the ­development, too. If a significant percentage of these other homes have new-looking roofs but the one for sale does not, it’s very likely that this home will need a new roof in the coming years, a major expense. 

Cracks, gaps or water damage where an addition connects with the original structure. Problems are particularly common when different parts of a home are built at different times. Rainwater sometimes sneaks in where the roof of an addition joins the existing roof…and additions sometimes settle after construction, causing them to separate slightly from the home. 

To identify an addition, note whether the house has a section that extends outside an otherwise rectangular footprint…whether it has an element that similar homes in the neighborhood lack—Google’s satellite view can help with this if it isn’t obvious from the street—and/or whether it has a section where the siding or roofing is visibly different from the rest of the house. 

If a house does appear to have an addition, closely examine where this addition connects with the house, from both inside and outside the home. Cracks and gaps in walls or ceilings here—or signs of patches covering cracks and gaps—might mean that the addition is pulling away from the home as it settles or that it was poorly constructed. Slight differences in floor height or sloping floors inside an addition could suggest similar problems.
Discolored walls or ceilings or musty odors near where additions meet the main structure could mean that rainwater is sneaking in. 

Sloping or sagging floors. Uneven floors could point to potentially serious problems with the home’s foundation. One way to test for subtle sloping is to open interior doors half way and see if they drift, either farther open or closed. A single door drifting might be a sign of nothing more than a poorly hung door…but several drifting suggests a foundation problem. 

Other signs of potential foundation problems include molding that’s pulling away slightly from walls, floors or ceilings…cracks in walls, especially around doors, windows or where walls meet ceilings…doors that fail to latch properly…and/or sticking doors—though sticking doors also could signal that the door has warped or expanded slightly on a hot day. Cracks in a foundation itself might suggest a problem, but not necessarily—that’s something to discuss with a home inspector. 

Mold odors in overlooked spots. It’s no secret that musty odors in a home could suggest mold problems. Trouble is, most buyers fail to check some common musty-odor trouble spots. Stick your head into cabinets under kitchen and bathroom sinks, and take a whiff. Do the same in closets that are on the opposite side of walls from bathrooms and also
in attics. 

Patched flooring. If you see sections of tile, carpet or wood flooring that don’t perfectly match the rest of the floor, that section of floor might have been pulled up to allow access to a structural, electrical, plumbing or HVAC component that failed underneath. On the other hand, it might be pulled up because of something as simple as a stained carpet or a broken tile. 

If you decide to pursue the home, have your real estate agent ask the seller to explain, in writing, why the flooring was patched. State laws vary, but if you buy the property and it later becomes clear that the seller misrepresented the reason for the patch, he/she is likely to be liable for any repair costs that are necessary as a result of the misrepresentation. And of course, when you hire a home inspector later in the purchase process, ask his/her thoughts about the reason for the patch.

Drywall patches larger than a doorknob. Small dings in drywall are common and not a big deal. They’re usually the result of someone carelessly carrying something large through the home…or doors being swung open too forcefully. But if a hole is larger than the size of a doorknob, it often means that someone had to cut into the wall to access something behind it, as with floor patches. An expertly done drywall patch that has been painted over can be tough to spot, but often, if you look closely, you can see slight discoloration or unevenness, especially if the homeowner attempted a DIY job and/or painted over only the patched area rather than the entire wall. Pay particular attention to…

Patches to walls that you ­suspect could have pipes inside. These ­patches could point to serious and potentially recurring plumbing problems and/or mold issues. A patched exterior wall in a kitchen or bathroom might contain pipes that have a history of freezing and bursting, for example. Also check the opposite side of interior walls supporting showerheads for ­plumbing-related patches. In many homes, the backsides of bathroom walls are hidden inside bedroom closets. Peek inside these closets—push hanging clothes out of the way if necessary—to search for patches.

Patches on ceilings. This might suggest rainwater coming in through the roof…or a leak from an HVAC component located in the attic. 

Drywall patches don’t always point to serious and ongoing problems, but as with floor patches, it’s worth asking both the seller and your home inspector for an explanation.