You may be quite handy around the house, but when it comes to these home improvement projects, it’s best to leave it to a professional.

Home DIY can save you money (and give you a great sense of accomplishment, if done properly). Plus, there are tons of resources on the Internet to guide you along. These guides work for simple jobs like changing a leaking faucet, or repairing the waterproof seal around your shower door.

But in these cases, you’re better off finding recommendations for a qualified service professional. Without proper training or expertise, any slips ups with these jobs could result in costly repairs, or worse, serious injury.

1. Electrical Work

Red or blue wire? What about the black wire? Does it connect to the silver screw or the brass screw?

Not everyone is handy when it comes to electrical work, like wiring or installing electrical equipment. There’s no harm in not knowing. But you will be putting yourself in harm’s way if you try to DIY this one without proper instructions. Electrical work should be left to the professionals. They know how to handle wires and how to insulate them so that they don’t cause any damage to you or your home.

2. Roof Work

For landed properties in Malaysia, the most common roof problem is the mystery leak. A leaky roof can be one of the most frustrating things to solve, and one of the most costly if not solved properly. A roof leak can also cause many other problems, such as mould, rot, and water stains coming down the inside walls.

First of all, you’ll need specialised tools and equipment, which you’re not likely to have. Secondly, you’ll need to have lots of time. Pinpointing a leak can take many hours, as you climb up and water different sections of your roof and wait for the drip drip sound. Finally, let’s not forget the risk of falls. You could get seriously injured if you fall from the ladder or slip from the roof.

3. Plumbing

Beyond changing taps and replacing toilet flushing systems, doing more complex plumbing jobs on your own can be bad news. You may think by doing your own plumbing you can save money, but if it’s something you haven’t done before, you could cause more harm than good. Bad plumbing can wreck paint, damage electrical wiring, and – if you live in an apartment or condo – cause a problem with the downstairs neighbour. Re-routing sewage pipes and extending hot water lines also involve serious planning and welding experience, so calling an expert is a smart idea.

4. Tiling

Tiling is definitely a lot harder than it looks. That’s why Malaysians always refer to the tiling professional as “si fu”. You cannot simply fix tiles onto your walls and floors and be done with it. You need to make sure they are level, are cut perfectly, and waterproofed (especially for bathroom tiles). Mess this up, and it’ll cost you twice as much to repair.

5. Wall Hacking

We’ve all been to IKEA and seen that hole in the kids bedroom section where they can crawl into the hallway. Looks like a cool idea, doesn’t it? But hacking walls will requires the expertise of a structural engineer, not to mention serious equipment. If the wall simply separates rooms it would be much easier to break. On the other hand, if it’s a supporting wall, then proper and cautious planning is required. Plumbing and wiring is also hidden in walls. And if you knock those down, you could be in serious trouble.