DIY home improvements can be hugely rewarding, and a great way to save money on repairs and maintenance. But choose the wrong projects to tackle yourself, or overstretch your abilities, and your time and effort will be wasted. More than that, you might have to fork out more money just to have that same work redone correctly. There are also tasks that are simply too dangerous for homeowners to tackle themselves, even if you feel confident in your abilities.

So before you pick up that drill, use the following advice to figure out which projects you can do yourself, and which are best left to the professionals.

Don’t do yourself more harm than good

It’s easy to rule out certain types of projects right away: those that have the potential to seriously injure you or severely damage your home. It can take a great deal of training and experience to become a fully qualified professional electrician, plumber or construction expert. If you’re at all uncertain about your own skills, you should probably steer clear of any technically-skilled DIY

Beware of any projects that could affect the structural integrity of your home, such as tearing down walls and converting attic space. Knocking down a wall might seem pretty simple, but if it’s load-bearing, or you’re not certain of what electrical wiring or plumbing you might find behind it, you could be in for some serious trouble.

HowStuffWorks lists a number of reasons you should proceed with caution when it comes to DIY home repairs, including three projects you probably ought to skip: asbestos removal, roofing repairs, and gas appliance maintenance.

Don’t compromise your home’s safety and security

In securing your home, you really oughtn’t leave anything to chance when it comes to making sure you and your family are safe. If you have good knowledge of replacing door locks and installing shutters, great! But anything more complex than fixing a latch will likely take a professional.

If you’re installing home CCTV, for instance, you are likely doing so to record images that could help bring burglars to justice should they break into your home. But if your CCTV system is flawed, the images it records may be inadmissible in court.

There’s no one size fits all when it comes to CCTV installation, meaning you’re unlikely to find adequate instruction online. Professional security firms can advise you on what to consider when installing CCTV in your home, including how to get the best coverage from your individual cameras, and how to make sure everything is wired up correctly to record any intruder in the act.

The same goes for burglar alarms. Simply looking the part might help deter burglars from your home, but if there’s even the tiniest error in the electrical circuit or your motion detectors aren’t quite positioned correctly, the entire system can fail, leaving your home especially vulnerable. What’s more, your home insurance policy likely won’t pay out in the event of a break in if your burglar alarm fails to function because it wasn’t installed by a certified professional.

Decide whether it is worth your time and effort

Tackling home repairs yourself can save you money, but that comes with a cost: time and energy. Before you even begin to consider whether you’re capable of doing a project, think about whether it’s worth that investment of time and effort.

Even though DIY might seem like the cheap option, it might end up costing you more in the long run. Keep in mind that, while you might save on labour by doing a project yourself, the materials themselves could cost more than you think, especially since the pros tend to benefit from wholesale pricing, and know how to source high quality materials from scrap yards and reuse centres.

That’s not all upfront. When it comes to selling your home or arranging for any future repairs you decide are a little beyond your expertise, having DIY’d it previously can put anyone off. Some professionals won’t touch a gas system that’s not covered by a Gas Safe certificate, for example, and you certainly can’t rent your home out without one.

You wouldn’t buy a car with no MOT and no service history: you can’t be sure what you’re getting yourself in for. It’s the same for your home: where’s the proof that everything is up to scratch? You might find yourself having to pay over the odds as a result.

Be realistic about DIY improvements

When you’re just starting out, build confidence with small projects and you’ll find your skills will grow from there. For example, change an electrical outlet before you tackle rewiring a room, or change a leaking faucet before trying to install a new sink. And don’t neglect the value of online instruction videos and manuals—learn from others and you’ll soon become an expert yourself.

You could also only DIY the parts of a project you’re more confident with. You might tackle the parts that are more labour-intensive, but not necessarily as skilled, like painting. The US National Education Association says 30% of the cost of painting is labour, which means you can make real savings even when you outsource the rest.

Some DIY projects can be hugely satisfying and become a real sense of pride. Garden landscaping, re-decorating and building furniture are all relatively simple home tasks you can sit back and enjoy in little to no time at all. If you’re tackling this sort of thing over the weekend, there’s scope to get the whole family involved, which could mean some serious bonding time too. But when it comes to risky home improvement projects, it might just be safer in the long run to call in a professional.