With a record number of people staying home for extended periods of time in 2020 due to the COVID-19 pandemic, home remodeling projects surged in popularity. Whether it was updating kitchens, transforming spare bedrooms into home offices, or giving bathrooms a much-needed facelift, homeowners across the country found themselves taking on improvement projects as a way to stay busy and make their spaces more functional and enjoyable.

Do-it-yourself (DIY) home improvement projects can be incredibly rewarding—not to mention cost-saving—when executed properly. There’s a unique sense of pride that comes from upgrading your space with your own two hands. However, many homeowners quickly discover that remodeling is far more complex than the online tutorials and weekend TV shows make it seem. Between navigating permits, choosing the right materials, understanding structural implications, and mastering the necessary tools and techniques, it’s easy to get in over your head.

While the motivation to save money is valid, a hopeful DIY renovation can swiftly spiral into a stressful, time-consuming, and costly disaster if you’re not prepared. In fact, some of the most expensive remodeling mistakes we’ve seen started with the best intentions—and ended in ruined materials, unsafe structures, or the need to hire a professional to undo and redo everything.

To help you avoid some of the most common pitfalls, we’ve compiled a list of the most expensive and scary remodeling blunders we’ve witnessed homeowners make. From kitchen layouts gone wrong to botched plumbing installations and dangerous electrical work, these real-life cautionary tales serve as a reminder that sometimes, calling in a pro is the best investment you can make.