Before you purchase a property, it’s important to get a home inspection. Sometimes there are issues with a house that aren’t visible to the untrained eye, and may end up ultimately being a deal breaker. Most real estate agents advise potential buyers to hire home inspection contractors to determine whether or not they should renegotiate or back out of a deal. It’s possible these contractors won’t find anything wrong with the house, but some buyers aren’t so lucky.

“Suppose your inspectors discover the $200,000 house you want to buy needs $20,000 of corrective work for termite and dry-rot damage, foundation repairs and a new roof. Big corrective work bills can be deal killers,” say​Eric Tyson and Ray Brown in their book, “Homebuying for Dummies.”

Here are some common parts of a property where home inspection contractors often find problems:

Decks – In addition to potentially leading to water damage in the homes, many decks built by ambitious homeowners may not be safe or up to code. Fixing this part of the property can be expensive, and often involves tearing it down and starting over.

Electrical wiring – Faulty electrical wiring can cause house fires, so it’s important to determine if the house you’re hoping to purchase is safe. Additionally, knob and tube wiring or aluminum wiring – often found in old homes – can be very expensive to replace.

Roofs – As the roof ages, it can end up breaking down and allowing moisture into the home, leading to all sorts of potential problems. Although many of the materials used for roofs have a long life expectancy, it’s still a part of the home that’s essential to have checked out.