15 of the Most Common Beginner DIY Mistakes (and How to Avoid Them)

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No matter how new or how well-built, every house needs work or maintenance on a regular basis. You can pay professionals to do it all, of course, but if you're looking to save a little money (or just want to learn and be in control of your home maintenance fate), there are plenty of home repair jobs that can be DIY'd. If you're a beginner who's just getting started on DIY maintenance and repair, however, you should watch out for some easy and common mistakes inexperienced DIYers make.

While some of these mistakes will be obvious the moment you make them, it's also easy to get through an entire project and experience superficial success, only to see that success slowly fade into failure because you've made a simple error. If you go into your next project with these easy DIY mistakes in mind, however, you can avoid a lot of problems.

Over-tightening is never a good idea

One of the most common mistakes beginner DIYers make is to assume that if tight is good, extra tight is better. This is especially true for plumbing jobs. We all fear water leaks and how easily they can destroy whole sections of your house, so it seems to make sense that when you've replaced the trap under your sink or swapped in a new drain or faucet, you should tighten those connections as much as you can. But over-tightening any connection, bolt, or screw can lead to disaster because it can cause small, subtle cracks that lead to failures and leaks that may not become evident until days or weeks later.

Additionally, tightening things until your eyes pop out of your head usually means that trying to remove that fitting or bolt later will be almost impossible. If you want to be kind to Future You (or the next person to own your home), avoid over-tightening. A good rule of thumb is to tighten plumbing until it's watertight, then stop, and to tighten screws and bolts only as much as necessary to get the job done.

Caulking an empty tub will cause your job to fail faster

Re-caulking a bathroom every few years is a very good idea. Caulk isn't forever, and even a tiny failure can allow damaging moisture to invade your walls and floors. And caulking is a DIY job almost everyone can do to an acceptable standard.

But if you're recaulking a tub, the easiest mistake to make is to do it dry. That's because water has mass. A gallon of water weighs about 8.34 pounds, and standard bathtubs hold anywhere from 80 to 100 gallons or more. When full, a tub will sink slightly, so if you caulked when it was empty, it will immediately strain and stretch the caulk, and your caulking job will fail pretty fast. Always caulk with a full tub.

Forgetting to shut off the power or water can lead to costly (or deadly) accidents

If your goal is to destroy your house and possibly yourself, then you should definitely dive into a DIY project without bothering to locate and turn off the water and electrical supply to the areas you'll be working on. Not only can one wrong turn of the wrench on a pipe send a torrent of water coursing into your house, but working with any exposed wiring that hasn't been confirmed to be cold is just foolhardy. Turning off the water and power to the areas you'll be messing with might seem like an unnecessary complication for a small, quick job, but if your hand slips or a component fails, you'll be very glad you took the time.

Not testing your equipment first can lead to problems later

When we buy tools, we assume they're going to work. And they usually do! But when that tool is crucial to the success of your DIY project, you should verify that it works as expected before you rely on it to be both accurate and safe to use. Stud finders, voltage testers, digital tape measures-any tool that measures or detects should be tested for accuracy by using it somewhere you know what the result should be (e.g., a working power outlet for a voltage tester) and/or comparing it to another tool or source (e.g., a physical tape measure or an object with a verified length). Otherwise, you could be working with inaccurate or incomplete information without realizing it.

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If you've never heard the term "kerf," you're not alone-few DIYers likely have. The kerf is the width of the cut your saw blade makes, in addition to whatever cut you've measured. This can be crucial, because that material is deleted from the wood you're working with (transformed into sawdust)-and that means your cuts can end up wider or narrower than intended.

For example, let's say you have a board that's a little more than 3 inches long (76.2 millimeters), and you're using a standard circular saw blade that's about 3mm thick. If you cut that board in half and push the two sides together, your board is now only about 73mm wide. The blade ate up and spat out 3mm of wood when you cut. If you score a straight line on that board to cut, say, one inch off, where you position the blade will make a small but potentially impactful difference-you want to position it on the other side from the piece you'll be using, so the kerf isn't part of the measurement. Otherwise, your cut will be just slightly too small. This doesn't matter in some projects-but if accuracy is a concern, keep the kerf in mind.

Skipping checking to make sure you aren't drilling into pipes or wiring can cost you

You're about to hang some shelving on the wall. You've measured twice, you have your screws and anchors. You double-check the bit size in the drill, and start drilling away. Moments later, water starts pouring out of your drill hole, or there's a spark, and your lights go off. Congrats! You just drilled into a pipe or electrical wiring inside the wall. Assuming you're still alive, you have a mess to clean up.

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A wall scanner is an indispensable tool whenever you're going to drill into a wall. It can detect live wires and plumbing, giving you a warning before you drill into disaster. If the wiring and plumbing were done correctly, there should be metal stud guards in place, so if you encounter unexpected resistance when drilling into the wall, it's best to assume you're aimed right at something vital and hitting the guard that's in place to prevent disaster. In other words, don't consider it a challenge to drill through whatever's slowing you down. Back out, take a breath, and investigate.

Skipping the "cleaning" step before you paint can ruin everything

You're in a groove-sanding, cutting, demo-ing, and making progress. Everything looks good, so you start to paint. And your paint job looks awful. It's bumpy and it might even start peeling immediately. Why? Because you didn't clean first. All that sawdust and drywall dust and tile dust has settled like a film on every surface, including the vertical surfaces of your walls, where it can be impossible to see. When you paint over dust like that, it will look terrible (at best) and fail to adhere properly (at worst). Always vacuum and wipe down every surface before you move to the finishing stages of your project.

Relying too much on painter's tape can lead to sloppy results

The most common mistake first-time painters make is believing that painter's tape is a magical material that results in crisp, perfect lines every time. Painter's tape is useful stuff, and it can certainly help you get a clean line and protect areas from accidental paint. (One trick for cleaner lines is to place your tape, then paint over the edge of the tape with the color beneath it, creating a seal. Let that edge coat dry, then paint using the new color. Remove the tape before the paint cures, and you'll have a crisp border.)

But painter's tape is not magic, and you still need to use proper painting technique if you want truly clean lines. That means learning how to use a cut brush properly, taking your time even if you've taped everything off, and not overloading your brush with paint. Even the best painter's tape can let paint bleed through if you're smearing too much on.

Inaccurate plate cutouts will make installing outlets and switches doubly difficult

When hanging drywall or tile DIY, making cuts for light switches and power receptacles can be a challenge. Aside from positioning them correctly, which can be a frustrating experience if you're inexperienced (you will waste so, so many tiles, trust me), the big mistake people make is not cutting them to the correct size. Too small, and you won't be able to fit the outlet or receptacle into the box or attach the wall plate properly. Too big, and you'll either have to cut a new tile or piece of drywall or buy a jumbo plate to cover your shame. (Full disclosure: There might be two of these in my bathroom right now).

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An easy mistake newbies make when using power drills for the first time is stripping screws. The bit in your drill is harder than the head of your screw, so if things go wrong, your drill can 100% wear down your screw until there's nothing left to grip, leaving you with a frustrating mini-project called "Using Pliers to Remove Screws." This usually happens because inexperienced DIYers just pull the trigger on their drill and go full-speed ahead. By the time they realize the bit has jumped and they're stripping the screw, it's too late. There are a few basic things you should do to avoid this fate:

1. Use the right bit. Screwdriver bits come in different sizes and formats. Make sure the bit you're using fits snugly into the screw and doesn't float around or hover on top. Even if there's some purchase when you turn the bit at a slow speed, an imperfect fit will pop out at high RPMs.

2. Start slow. Don't just jam the drill's trigger and launch it into hyperspeed. Ease into it and increase the speed steadily. Push in as you drill to ensure the bit stays seated.

3. Stay perpendicular. Don't let the drill droop at an angle. You want to come at the screw perfectly straight. If you need a ladder or other tools to accomplish this, get them.

If you follow those simple steps, your chances of stripping a screw go down dramatically, and your chances of a happy ending to your DIY project go up. If you have the discretion to choose your fasteners, consider using screws with different drive types, like hex or torx. These are less prone to stripping than your standard slotted or Phillips screw.

"Making do" with the tools you have can go terribly wrong

A common mistake newcomers to DIY home maintenance and repair make is relying on the basic tools they have on hand instead of buying, renting, or borrowing the correct tools for the job. A lot of folks have a hodgepodge of tools they picked up along the way-a hammer, some screwdrivers, and a pair of pliers, for example-and these are sufficient for taking care of minor projects when you're renting an apartment or relying on someone else to make repairs. But it's a huge mistake to try to make those tools work for every project. If all you have is a cheap hand saw, for example, trying to make intricate or shaped cuts will be a nightmare, when you could just acquire a decent jigsaw. Making do with what you have is a recipe for disaster.

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A common misconception among newbies to the joys of DIYing through a home repair or maintenance project is that materials within a given category are broadly similar and can be used interchangeably. But using, say, exterior paint on an interior job, or acrylic caulk (which isn't waterproof) in a wet area like a shower, can ensure disastrous results, with the added fun of doing the job a second time. These materials are formulated for specific environments-exterior paint, for example, is designed to withstand exterior forces like wind and rain, and will actually degrade pretty fast on an interior application-so make sure you're using the right ones.

Not documenting when you disassemble something will cause trouble down the road

It's a hard lesson every aspiring DIYer learns at some point: Taking stuff apart is easy. Putting it back together is hard. But the biggest mistake you can make when disassembling something for a repair job is failing to document the process. Taking photos of what it looks like before you start ripping it apart (and taking more photos as you progress) will be invaluable when you try to put it all back together, as will making notes about and labeling every fastener and piece of metal or plastic you pull out. Don't imagine you'll magically remember how it all goes together, or that it'll be instinctive-often the most efficient way to engineer something is also the least obvious.

The time saved by eyeballing your measurements is never worth the risk

Most homes are not level. Settling and the natural cycle of expansion and contraction mean it takes just a few years for everything in even a new home to be maddeningly out of plumb. Yet every day, someone thinks they can just eyeball stuff-getting things level and measuring materials accurately-without using the proper tools.

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Getting level is a particularly seductive trap, because your eyes lie to you. When putting up shelves, for example, the lines of the room-where the wall meets the ceiling, for example-may look level to you, and you can maybe eyeball your way to making the shelves level with those lines. But if your walls are slightly out of plumb, then your shelves will be on a subtle slant, and everything you put on them will slide right off. Invest in a tape measure and a simple bubble level instead of trusting your foolish senses.

Overworking paint can mean redoing everything

Painting is one of the cheapest and easiest DIY projects you can undertake, and paint can be a surprisingly powerful renovation that makes a space feel fresh and new. Just about anyone can learn to paint walls pretty decently-all it takes is proper prep, the right tools, and a patient approach. But a common DIY mistake when painting is to overwork the paint. This can happen when you apply more fresh paint over a section that hasn't completely dried, which results in a splotchy, uneven look, or when you use too much pressure when using a paintbrush, which results in visible stroke lines. Modern paint contains leveling agents that will coax it into a uniform sheen if left to do its work. If you think your first coat was spotty, wait for it to fully dry before applying a second coat.