Water can damage a foundation in countless ways, so homeowners should look to experts for the dos and don’ts.

Water is not always our friend. Sure, we drink it, swim in it, and need it to survive, but when it comes to homes, it can destroy the foundation, says home inspector Thomas Dabb of Immaculate Home Inspections in South Orange, N.J.

Water can enter a home from the exterior and interior, so buyers and homeowners need to keep their eyes open for signs of its presence—or worse—its damage.

The good news is that there are many experts available to spot and diagnose a problem and suggest the best fix. Water expert Steve Barckley with Exceptional Stone Products in Livingston, N.J., believes that homeowners should start by doing everything possible on the outside of the homes to correct problems and divert water away from a foundation.

Share these seven solutions with clients to help them minimize a foundation’s damage in various scenarios.

1. Improve grading. The slope of a property may direct water toward the base of a single-family house or multifamily dwelling rather than away. Cracks or openings in the foundation then allow it to enter, as well as through higher-level walls, the roof, and other entry points. Fix: “Be sure the grade slopes away from the house,” says Bill Coulbourne, a structural engineer whose eponymous company is near Annapolis, Md. A berm of soil or a swale with planting can prevent water from making its way to a foundation, says Cary Jozefiak, a home inspector with HomeTeam Inspection in Chicago. Caveats: This approach requires periodic maintenance to be sure the berm doesn’t erode. “It also needs to be directed so water doesn’t move toward a neighbor’s property,” Coulbourne says. Using a French drain to allow water to dissipate slowly from near the foundation into the landscape is more environmentally friendly than introducing it into the street to wash away, says Barckley. French drains also require some preventive maintenance to avoid clogging, Jozefiak says.

2. Waterproof a foundation. Keeping the foundation dry will prevent moisture from accumulating on the outside or entering inside. Fix: If wet, the best fix is to waterproof the exterior perimeter and interior walls of a basement or crawl space to prevent capillary action from building up, says New York City architect Victor Body-Lawson of Body Lawson Associates. “What we try to do is create an envelope around a building so water can’t enter through its skin, sometimes with a rain screen that drains water down and out to a storm drainage system,” he says. A sump pump will help if there’s moisture and water inside. It must drain far enough from a house, so water doesn’t recycle back inside if the property slopes or there’s an opening. Home inspector David Rose of Astute Home Inspections in Plainfield, N.J., suggests the drain be at least 5 feet from a house. A backup battery will prove useful if power fails.

3. Install gutters and downspouts. Water flowing off a roof will land near a house and possibly cause damage over time. Fix: A good line of defense is to have both gutters and downspouts installed around a home or building’s perimeter. The downspouts should extend far enough to carry away the water rather than have it sit near a foundation. Jozefiak recommends six feet away from a house. To keep gutters and downspouts functioning, they must be cleaned. How often to do so may depend on the trees near a house, Coulbourne says.

4. Keep large trees and bushes away from a house. Tree roots and other plant materials try to grow toward water, which can destabilize a structure and penetrate foundations, says Rose. Fix: If large trees already grow near a house, check that plumbing lines are free, and confirm there aren’t foundation cracks. If problems arise, the tree may need to be taken down or bushes transplanted, Body-Lawson says. Sacramento, Calif.-based landscape designer Michael Glassman suggests consulting a licensed arborist to check roots, stability, and if the tree should be removed. “The best time to remove trees is in winter when they are dormant,” Glassman says.

5. Don’t ignore diagonal cracks. Movement, temperature changes, and time may cause foundation cracks to develop. But large diagonal ones require attention from a structural engineer to avoid bigger issues. “Visual clues appear before structural inadequacies do,” says Madison, Conn.-based architect Duo Dickinson. Among the problems are moisture and salt destroying anything made of steel and non-pressure-treated wood, which may rot, Dickinson says. Fix: Cracks suggest settlement and send a red flag that something might be wrong with a foundation, says Body-Lawson. “It might have sagged but it may not deteriorate further. However, if it continues to do so, the foundation needs underpinning.” Cracks that appear in foundation walls due to settlement may be visible in a first floor’s interior, too, says Coulbourne. Hairline cracks are common, but when it’s a quarter-inch in width and V-shaped, it may indicate pressure on an exterior wall.

6. Check for significant leaks and stains, especially efflorescence in a basement. “An unfinished basement is the best basement because it’s easier to see problems,” says Rose. Fix: When a basement is finished, experts recommend looking for clues. For example, a rust color that shows through paint can be a sign of moisture, says Barckley. Efflorescence—white powder left behind from minerals in water—may also appear. Coulbourne says that mold is another indicator, most likely visible at the base of a wall where moisture accumulates. Use your nose, too, he says. “If you walk into a damp basement, you can smell that,” he says. Sometimes areas covered over need to be checked. For example, Rose may pop open ceiling tiles to examine what’s behind them.

7. Learn why interior or patio floors may slant. It could be that a house is settling, which happens over time, says Body-Lawson. “Old houses may sag a little and then stop,” he says. But if the floor or patio was level and now slants, it might be time to hire a structural engineer, says Jason Chang of Jersey Inspections in Verona, N.J. Fix: Floorboards, tiles, and carpet can be picked up, joists shimmed, and a new layer installed, says Body-Lawson. If water gets under pavers outdoors, they may need to be taken up, the pitch of the patio checked, a membrane or drainage system installed, then pavers put back, Jozefiak says.