15 Most Common Mistakes Beginner DIYers Make (and How to Avoid Them)

No matter how new or well-built a home is, every home needs regular repairs and maintenance. Of course, you can hire professionals to do all of this, but if you’re looking to save a little money (or simply want to learn and monitor the condition of your home), there are plenty of repairs you can do yourself. However, if you’re a novice just starting out with DIY repairs and maintenance , you should be wary of some common mistakes inexperienced DIYers make.

While some of these mistakes will become obvious the moment you make them, it’s easy to build a project to superficial success, only to see that success gradually turn to failure due to a simple mistake. However, if you approach your next project with these common mistakes in mind, you can avoid a multitude of problems.

Over-delaying is never a good idea.

One of the most common mistakes beginners make is assuming that if tightness is good, then even more tightening is even better. This is especially true for plumbing. We all fear water leaks and how easily they can ruin entire sections of the house, so it seems logical that after replacing a sink trap or installing a new drain or faucet, we should tighten these connections as tightly as possible. But overtightening any connection, bolt, or screw can lead to disaster, as it can cause small, unnoticeable cracks that lead to breakages and leaks that may only become apparent days or weeks later.

Furthermore, overtightening something usually means that removing that fitting or bolt later will be nearly impossible. If you want to be kind to your future self (or the next owner of your home), avoid overtightening. A good rule of thumb: tighten plumbing fixtures until they’re completely tight, then stop, and tighten screws and bolts only as much as necessary to get the job done.

Sealing an empty bathtub will cause the job to fail more quickly.

Re-sealing bathroom joints every few years is a very good idea. Sealant doesn’t last forever, and even the slightest damage can allow harmful moisture to penetrate the walls and floor. Furthermore, sealing is a job that almost anyone can do themselves to a reasonable standard.

But if you’re resealing a bathtub , the most common mistake is doing it dry. That’s because water has mass. A gallon of water weighs about 8.34 pounds , and standard bathtubs hold 80 to 100 gallons or more . When a bathtub is full, it settles slightly, so if you reseal when the tub is empty, the caulk will immediately stretch, quickly ruining your sealing job. Always reseal when the tub is full.

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

If your goal is to destroy your home and possibly yourself, then you should definitely tackle the repairs yourself, without bothering to find and shut off the water and power in the areas where you’ll be working. Not only can one wrong turn of a wrench on a pipe cause a flood, but working on any exposed wiring that hasn’t been cold-tested is simply foolhardy. Turning off the water and power in the areas where you’ll be working may 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.

Failure to check equipment beforehand can lead to problems later.

When we buy tools, we assume they’ll work. And usually, they do! But if a tool is critical to the success of your DIY project, you need to ensure it works properly before relying on its accuracy and safety. Stud finders, voltmeters , digital tape measures—any tool that measures or determines parameters should be tested for accuracy by using it in a location where you know what the result should be (such as a working voltmeter outlet) and/or comparing it to another tool or source (such as a regular tape measure or an object of verified length). Otherwise, you could be working with inaccurate or incomplete information without even realizing it.

Forgetting about the kerf width of your saw is the fastest way to ruin a precision cut.

If you’ve never heard the term “kerf width,” you’re not alone—hardly any DIYer has. Kerf width is the width of the cut a saw blade makes, in addition to the width you measured. This can be very important because this material is removed from the wood you’re working with (turned into sawdust), meaning your cuts may turn out wider or narrower than intended.

For example, let’s say you have a board just over 3 inches (76.2 millimeters) long and you’re using a standard circular saw blade with a thickness of about 3 mm. If you cut this board in half and join the two sides together, the board’s width will be only about 73 mm. During the cut, the blade sucked in and spat out 3 mm of wood. If you draw a straight line across the board to cut, say, one inch, the position of the blade will make a small but potentially significant difference—you should position it on the opposite side of the piece being cut, so that the kerf width isn’t included in the measurement. Otherwise, your cut will be slightly smaller than necessary. In some projects, this won’t matter, but if accuracy is important, consider the kerf width.

If you don’t check to make sure you don’t damage pipes or wiring while drilling, it could cost you dearly.

You’re about to hang some shelves on the wall. You’ve measured everything twice, you’ve got the screws and anchors. You double-check the drill bit size and start drilling. After a few moments, water starts pouring out of the hole, or a spark appears, and the light goes out. Congratulations! You’ve just drilled through a pipe or electrical wire inside the wall. If you’re still alive, you’ll have to clean up after yourself.

A wall scanner is an indispensable tool when drilling into walls. It can detect live wires and pipes, alerting you to potential problems. If the wiring and plumbing are properly installed, metal guards should be in place. So, if you encounter unexpected resistance while drilling into a wall, it’s best to assume you’re aiming directly at an important object and hitting a guard designed to prevent accidents. In other words, don’t treat drilling as a challenge if it slows you down. Step back, take a breath, and check.

Skipping the “cleaning” step before painting can ruin everything.

You’re in a good mood—sanding, sawing, demolishing, moving forward. Everything looks good, so you start painting. And your paint job looks terrible. It’s uneven and may even start peeling right away. Why? Because you didn’t clean it up first. All that wood dust, drywall dust, and tile dust has settled like a film on every surface, including vertical wall surfaces where it’s impossible to see. When you paint over that dust, it will look terrible (at best) and adhere poorly (at worst). Always vacuum and wipe down all surfaces before moving on to the final stages of the project.

Excessive use of masking tape may result in poor quality work.

The most common mistake beginner painters make is believing that painter’s tape is a magical material that always produces crisp, perfect lines. Painter’s tape is a useful tool, and it can certainly help you achieve a clean line and protect areas from accidental paint smudges. (One trick for achieving cleaner lines is to apply tape and then paint the edge of the tape with paint the same color as the paint underneath, creating a protective layer. Let this layer dry, then paint the new color. Remove the tape before the paint dries, and you’ll have a crisp edge.)

But masking tape is n’t magic, and to achieve truly clean lines, you still need to use proper painting technique . This means learning to use a brush correctly, taking your time even if you’ve covered everything with tape, and not overloading the brush with paint. Even the best masking tape can leak paint if you apply too much.

Inaccurate cutouts in the mounting plate will make installing sockets and switches doubly difficult.

When installing drywall or tile yourself, cutting holes for switches and outlets can be a tricky task. Besides getting their placement right, which can be frustrating for inexperienced DIYers (trust me, you’ll ruin a ton of tiles), the most common mistake is improper cutting. Holes that are too small won’t fit, and the outlet won’t fit in the mounting box or secure to the mounting plate. Too large, and you’ll either have to cut a new tile or piece of drywall, or buy a huge mounting plate to cover up the mess. (Honestly, I probably have two of those in my bathroom right now.)

Incorrect tightening and stripping of screw threads can stop any work.

One common mistake beginners make when first using a drill is stripping screw threads . The drill bit is harder than the screw head, so if something goes wrong, the drill can completely wear down the screw until it starts to stick, leaving you with the annoying mini-task of “using pliers to remove screws.” This usually happens because inexperienced DIYers simply pull the trigger on the drill and run at full speed. By the time they realize the bit has slipped and the screw is stripping, it’s too late. There are a few basic steps you can take to avoid this fate:

1. Use the correct bit. Screwdriver bits come in a variety of sizes and shapes. Make sure the bit you’re using fits snugly into the screw and doesn’t wobble or hang up. Even if the bit has some traction when rotating at low speeds, a loose fit will cause it to pop out at higher speeds.

2. Start slowly. Don’t pull the drill trigger abruptly or turn it on at high speed. Press gently and gradually increase the speed. Squeeze the trigger as you drill to ensure the drill bit is held securely.

3. Maintain a perpendicular position. Don’t let the drill tilt at an angle. You need to be perfectly straight with the screw. If you need a ladder or other tools for this, use them.

By following these simple steps, you’ll significantly reduce the risk of stripping screw threads and increase your chances of successfully completing your DIY project. If you have a choice of fasteners, consider using screws with different drive types , such as hex or Torx. They’re less prone to stripping than standard slotted or Phillips-head screws.

Trying to make do with the tools available can lead to dire consequences.

A common mistake new home repair and maintenance professionals make is relying on basic tools they already have instead of buying, renting, or borrowing the necessary ones. Many people have a set of tools they’ve acquired along the way—for example, a hammer, a few screwdrivers, and pliers—and these are sufficient for small jobs when renting an apartment or relying on someone else for repairs. But trying to use these tools for every project is a huge mistake. If you only have a cheap handsaw, for example, trying to make complex or curved cuts will be a nightmare, whereas you could simply invest in a good jigsaw . Using what you have is a surefire recipe for disaster.

Using materials that are similar in composition but not quite compatible in characteristics can really make a huge difference.

A common misconception among DIY home repair and maintenance novices is that materials within the same category are generally similar and interchangeable. However, using, say, exterior paint indoors or acrylic sealant (which isn’t waterproof) in a wet area like a shower can lead to disastrous results, requiring the job to be redone. These materials are designed for specific conditions—for example, exterior paint is designed to withstand elements like wind and rain, but will actually degrade quite quickly when applied indoors—so make sure you’re using the right materials.

Lack of documentation when disassembling something will lead to problems in the future.

Every budding DIYer sooner or later learns a hard lesson: taking things apart is easy. Putting them back together is hard. But the biggest mistake you can make when taking something apart for repair is not documenting the process. Photos of what the item looks like before you start disassembling (and additional photos as you go) will be invaluable when you try to put it back together, as will notes and labeling every fastener and metal or plastic component you remove. Don’t expect to magically remember how to put it all together or that it will be intuitive—often the most effective way to construct something is also the least obvious.

Saving time by visually measuring is never worth the risk.

Most houses are uneven. Settling and the natural cycle of expansion and contraction mean that within just a few years, even in a new home, everything begins to shift significantly from vertical. Yet, every day, someone thinks they can simply eyeball everything—level everything and measure materials precisely—without using the proper tools.

Leveling is a particularly tempting trap because your eyes can play tricks on you. For example, when installing shelves, the room’s lines—the junction of the wall and ceiling—may appear straight to you, and you might be able to visually align the shelves along these lines . But if your walls are slightly uneven, the shelves will be slightly tilted, and anything you place on them will simply slide off. Instead of relying on your own instincts, invest in a tape measure and a simple bubble level.

Over-treating the paint can result in having to redo the entire job.

Painting is one of the cheapest and easiest DIY projects you can undertake, and paint can be a surprisingly effective way to update a room, giving it a fresh, new look. Almost anyone can learn to paint walls fairly well—all it takes is the right preparation, the right tools, and patience. But a common DIY painting mistake is overdoing it. This can happen when you apply too much fresh paint to an area that hasn’t fully dried, resulting in a blotchy, uneven look, or when you press too hard on the brush, resulting in visible brushstrokes. Modern paint contains leveling agents that, when allowed to dry, will ensure a uniform sheen. If you feel like the first coat is blotchy, wait until it’s completely dry before applying a second coat.

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