If you’re new to homeownership, you’ll definitely want to avoid these easy-to-prevent mistakes that could cost you big time.

We know so well the thrill of owning your own house — but don’t let the excitement cause you to overlook the basics. We’ve gathered up a half dozen classic boo-boos new homeowners often commit — and give you some insight on why each is critically important to avoid.

1. Not Knowing Where the Main Water Shutoff Valve Is

Water from a burst or broken plumbing pipe can spew dozens of gallons into your home’s interior in a matter of minutes, soaking everything in sight — including drywall, flooring, and valuables. In fact, water damage is one of the most common of all household insurance claims.

Quick-twitch reaction is needed to stave off a major bummer. Before disaster hits, find your water shutoff valve, which will be located where a water main enters your house. Make sure everyone knows where it’s located and how to close the valve. A little penetrating oil on the valve stem makes sure it’ll work when you need it to.

2. Not Calling 811 Before Digging a Hole

Ah, spring! You’re so ready to dig into your new yard and plant bushes and build that fence. But don’t — not until you’ve dialed 811, the national dig-safely hotline. The hotline will contact all your local utilities who will then come to your property — often within a day — to mark the location of underground pipes, cables, and wires.

This free service keeps you safe and helps avoid costly repairs. In many states, calling 811 is the law, so you’ll also avoid fines.

3. Not Checking the Slope of Foundation Soil

The ground around your foundation should slope away from your house at least 6 inches over 10 feet. Why? To make sure that water from rain and melting snow doesn’t soak the soil around your foundation walls, building up pressure that can cause leaks and crack your foundation, leading to mega-expensive repairs.

This kind of water damage doesn’t happen overnight — it’s accumulative — so the sooner you get after it, the better (and smarter) you’ll be. While you’re at it, make sure downspouts extend at least 5 feet away from your house.

Related: How to Prevent Water Damage

4. Not Knowing the Depth of Attic Insulation

This goes hand-in-hand with not knowing where your attic access is located, so let’s start there. Find the ceiling hatch, typically a square area framed with molding in a hallway or closet ceiling. Push the hatch cover straight up. Get a ladder and check out the depth of the insulation. If you can see the tops of joists, you definitely don’t have enough.

The recommended insulation for most attics is about R-38 or 10 to 14 inches deep, depending on the type of insulation you choose. BTW, is your hatch insulated, too? Use 4-inch-thick foam board glued to the top.

Related: Attic Air Leaks: How to Find and Seal Them

5. Carelessly Drilling into Walls

Hanging shelves, closet systems, and artwork means drilling into your walls — but do you know what’s back there? Hidden inside your walls are plumbing pipes, ductwork, wires, and cables.

You can check for some stuff with a stud sensor — a $25 battery-operated tool that detects changes in density to sniff out studs, cables, and ducts.

But stud sensors aren’t foolproof. Protect yourself by drilling only 1¼ inches deep max — enough to clear drywall and plaster but not deep enough to reach most wires and pipes.

Household wiring runs horizontally from outlet to outlet about 8 inches to 2 feet from the floor, so that’s a no-drill zone. Stay clear of vertical locations above and below wall switches — wiring runs along studs to reach switches.

6. Cutting Down a Tree

The risk isn’t worth it. Even small trees can fall awkwardly, damaging your house, property, or your neighbor’s property. In some locales, you have to obtain a permit first. Cutting down a tree is an art that’s best left to a professional tree service.

Plus, trees help preserve property values and provide shade that cuts energy bills. So think twice before going all Paul Bunyan.