Buying a home is one of the biggest investments most people make in their lives—but if you miss a few red flags it could end up being one of the mostly costly mistakes you’ll ever make. When you’re on the hunt for your dream home, these are the deal-breaking problems that mean you shouldn’t buy:

1) Structural Problems

Issues with a home’s structure or foundation might not always be obvious—but check for large cracks in an unfinished basement, or door frames that appear uneven for a hint. A home inspector will be able to confirm. A problem with a home’s foundation can cost you months of construction work and tens of thousands of dollars to repair—so unless you’re planning on a major fixer-upper these homes are best avoided.

2) Pests

Structural problems are best avoided, and so are the pests that can cause them. Tiny termites, carpenter ants, and other wood chewing insects can cost you thousands of dollars in repairs, so invest in a pest inspection before you drop a down payment. Common household pests like mice and cockroaches can also be difficult to fully eradicate and (in addition to just being creepy) can cause damage to electrical wiring and insulation.

3) Bad Neighbors

That pile of junk (the one covered in layers of ivy) in your potential new neighbor’s lawn isn’t likely to go away the second you move in—and it definitely won’t disappear if you ever decide to sell your home in the future. If you notice a dilapidated property next door, observe any noisy arguments, or are driven up the wall in a single showing by barking dogs, none of these problems will disappear once you move in. Plus, if they drive you crazy enough to leave your property value could suffer because of the junk on their lawn. You could cross your fingers and hope those bad neighbors move out first, but when you’re going to be stuck next to someone for a decade choose wisely.

4) Mold

Mold isn’t always obvious without an inspection, but it can cause serious health problems (especially in children) and is difficult to eradicate. If you notice odd musty odors or random paint patches designed to hide stains, that could be a tip off that mold is present. Your best bet is to have a home inspection and avoid any moldy properties.

5) Electrical Issues

Home buyers should be wary of homes with flickering lights and dead outlets, which could indicate improper wiring and electrical issues. Older homes are more likely to have outdated electrical panels and fuses (or even older knob and tube wiring) which is expensive to upgrade and can cause a range of problems, from constant tripped circuits to fires in severe cases.