For these home improvement projects, it's best to hire a pro

A do-it-yourself approach for home-improvement projects may reduce your initial costs — but for certain jobs, the risks far outweigh any potential savings. If any of these projects are on your to-do list, call in the pros unless you've got plenty of related experience.

Roof replacement. Any savings you might get with a DIY roof replacement could easily be eclipsed by the costs of making expensive mistakes or causing dangerous accidents. You will also need to climb ladders, lift heavy materials and navigate a steeply pitched surface high above the ground.

Roofers charge about $150 to $300 per roofing square in addition to the cost of materials, which typically brings the total price of installing a new roof over your existing one to about $5,400 to $10,900, according to the home services company HomeAdvisor. Removing the old roof or repairing damage can add to that cost. In some cases, homeowners insurance might cover some or all of these expenses.

Mold removal. Everyone's cleaned up a bit of mold at some point. But once mold infestation becomes widespread, it might become necessary to open up walls, lift up carpeting or take out fixtures to fully remove it and clean and dry the space thoroughly.

Professional mold remediation generally costs about $1,500 to $3,150, or $15 to $30 per square foot, according to HomeGuide, a home-services referral website.

To make sure that money is well-spent, go with an experienced, well-reviewed mold remediation specialist who can do a thorough job.

Toilet replacement. To install a new toilet, you will have to shut off the water; disconnect, drain and remove the old toilet; and seal and connect the new one. That's a manageable task for someone with basic plumbing knowledge. But if you are a DIY newbie, it's trickier. Improper installation, overtightening connections or simply dropping the toilet may cause serious damage.

The average labor cost for basic toilet installation runs between $70 and $190, according to the services marketplace website Thumbtack, and that doesn't include the price of the toilet.

Window replacement. Installing a window is a meticulous process, and any mistakes may leave your home unexpectedly vulnerable to the elements. Other pitfalls include the possibility that an improper installation may void all or part of the manufacturer's warranty.

Window installation usually runs between $175 to $700 per window, but can be much more expensive for high-end windows, according to Angie's List.

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