Is that crack serious? Foundation problems 101 (© David Gee/Alamy)

© David Gee/Alamy

Home foundations aren't typically a hot news topic, but an ongoing severe drought in Texas has left many homeowners there and elsewhere wondering how stable their homes really are.

The drought that some are comparing to the Dust Bowl has homes rockin' and rollin' as the parched ground beneath them cracks and settles. Homeowners are watering their foundations — to keep their abode in place — and forgetting about their grass.

But you don't have to live in the Lone Star State to have foundation issues. So how do you know if you're on solid ground? Here is a primer:

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Know your foundation
Foundations crack. That's why a foundation is usually composed of steel in concrete — to hold it together when it does. The key is knowing whether that crack means anything. "A lot of people will see cracks and they'll panic a little bit," home-improvement expert Danny Lipford says. "But not all cracks are the same."

Before we talk about cracks, though, it helps to know what kind of foundation your home rests upon. It's likely one of these types:

  • Homes in warm, dry climates frequently have a "slab on grade" foundation, which is a layer of concrete poured down on smoothed soil.
  • Another popular home foundation is "pier and grade beam"; a perimeter concrete beam supports the outer frame of the house, and piers in a crawl space support the middle section of the house.
  • Yet another type of foundation uses only piers drilled perhaps 20 feet deep, and the house rests atop them.

"What causes most foundation problems is soil expansion and contraction," says Jim Dutton, an owner of Du-West Foundation Repair in Texas and host of the radio show Texas Home Improvement. Texas is in the news, but Dutton says "every place along the Gulf Coast is more known for this" — Louisiana, Mississippi, Alabama. The reason: a black gumbo clay that was brought down during the last Ice Age, Dutton says. It also exists in the Atlanta area and in pockets elsewhere, including St. Louis and Denver. But even bedrock can move. The American Society of Civil Engineers has estimated that one-quarter of all the nation's homes have suffered damage caused by expanding soil.

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Looking for trouble
Wondering if you have problems? Here's what to look for:

Inside the house

  • Examine your walls. Look for cracks in the drywall that "would not run along with the drywall itself — in other words, it's jagged and runs off at a 45-degree angle," Lipford says. "As the foundation shifts, it literally tears the Sheetrock in two," Dutton says.
  • Shut the doors and windows. Look for doors and windows that stick, and not because of paint or other issues; a stuck door or window is an indication that the frame has been twisted by a shifting house."On the doors, you're not just looking for doors that are sticking, but doors that have a gap on the top of them," Dutton says. "Either one is an indication that there's been movement."
  • Pull up the rug. If you have a slab-on-grade foundation, check your floor. "If you're looking at a crack on the floor — which again is very common with a concrete slab — to gauge the seriousness of it, you can use a straight edge like a 4-foot level," Lipford says. "And you put it over the crack — not to see necessarily if it's level, but to see if one side of the crack is lower than the other." Many times, both sides are even, Lipford says; that would be more telling of an expansion and contraction crack, which is less worrisome. "But if one side is lower than the other, then one side (of your foundation) has dropped."
  • Get on your knees. If your home has a crawl space, look inside. If the dirt is exposed, see if the dirt is moist or not, "because that can indicate water intrusion," says Mike Schmidt, a partner with Denver-based Pinnacle Structural Services, and the company's lead inspector. A musty smell can indicate a lot of moisture, too, Schmidt says. On the other hand, if the ground in the crawl space is extremely dry and has cracks, that indicates that moisture was present, followed by a long, dry period — a situation that can also signal trouble because the ground "can lose its ability to sustain a dead load," he says.

Outside the house

  • Look up. "Most people think you look down at the foundation, but you don't," Dutton says. "You want to look at things higher up. If it was a two-story house, the damage would be more severe on the second floor than the first." Look for cracks above doors and windows, frieze-board separation on the corners (frieze board is a board that wraps around the house below the overhang) and — if it's a brick home — stair-stepping cracks in the veneer, Dutton says.
  • Look horizontally. Horizontal cracks across the foundation are often serious. "Horizontal cracks are caused by hydrostatic pressure — basically, too much water behind the foundation. It pushes on the foundation," Schmidt says. Here's a tip: Look down the outside of your house. Does the home appear to be hanging over the foundation, especially in the middle, as if the home is too big for its foundation? That's a tell-tale sign. "Most commonly it's because of too much water pressure, and that's commonly because of poor water drainage," Schmidt says. (We'll get to that.)
  • Read the cracks. Concrete foundations will often have some cracks. After all, concrete shrinks as it cures, and it can crack where it doesn't cure evenly. But what's a noteworthy crack?

Stair-step cracks, especially in masonry such as bricks, are common and are a tell-tale sign of some movement. If they're small, they might not be a huge concern — yet. But if they're a quarter-inch or more, they can indicate a foundation on the move, Dutton says.

And a vertical crack? "A more vertical line would indicate a more serious settling problem," Lipford says. Is the crack larger at the top than the bottom? That indicates a ground-heaving issue, where expansion of the soil is pushing up the foundation, Schmidt says. Is the crack larger at the bottom than the top? That usually indicates a settlement problem, where the foundation is dropping, because of compacting soils. But this rule doesn't always hold true, so an expert's eye can be important.

'A crack!' How to react
So you find a crack or two. Should you panic? Call in the cavalry? Get out the spackle? "Most hairline cracks are just shrinkage cracks," Schmidt says. "They're extremely common." He recommends putting a mark by any crack, noting its size and the date and then revisiting the crack each season to see if it has grown.

Should you fill in cracks? "If it's not leaking, no, leave it alone," Schmidt says. "That crack might be a sign of something that you might have missed," he says, and by filling it you're masking an issue that's trying to announce itself. Dutton agrees: Epoxy injected into a crack will only serve as a wedge when the foundation is later corrected, he says. Put something in the crack only after the home has been stabilized — at least two months afterward, Schmidt says, once the house has had a time to settle into its new position.

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