Retaining Wall Warning Signs to Check Before Fall Storms

A retaining wall spends every day holding back soil that would rather be somewhere else. Most of the time that work is invisible. Walls rarely fail all at once, though; they usually show strain for months or years first. Fall is a good time to walk your walls, because heavier rains add weight and water pressure behind them at exactly the moment a weakened wall is least able to take it.

Lean is the first thing to check. Stand at one end and sight along the top of the wall, or hold a level against its face. A wall that was built plumb, or with a slight intentional tilt back into the slope, and now tips forward toward the low side is losing ground to the soil behind it. Compare what you see with older photos if you have them. A wall that has leaned slowly over several years is easier to address than one that moved suddenly after a storm.

Next, look for bulges and cracks. A bulge partway along a wall means soil pressure is pushing harder there than the wall can resist. On a poured concrete wall, horizontal cracks deserve more concern than small vertical shrinkage cracks, because they can mean the wall is bending. On block walls, stair-step cracks through the mortar joints or blocks sliding out of line tell a similar story. Cracks that seep muddy water after rain show that water is moving through the wall instead of being drained away behind it.

Drainage is where most wall problems begin. A properly built wall gives water a way out: gravel backfill, often a perforated drain pipe near the base, and weep holes or outlets on the face. After a good rain, those outlets should run for a while and then stop. If they stay dry while the soil above is soaked, they may be clogged with silt or roots. If water seeps along the entire base instead, the drainage behind the wall may have failed. Clearing visible outlets is routine maintenance. Rebuilding the drainage behind a wall is a much bigger job.

Check the bottom and the top of the wall as well. Soil washing out from under the base undermines the footing. Gaps opening between the top of the wall and a patio or walkway above it, fence posts tipping outward, or a sinking strip of lawn just behind the wall all suggest the retained soil is moving. Tree roots working into the wall, or a large tree growing close behind it, add loads the original design may never have considered.

Not every finding is urgent. Hairline cracks, minor surface wear, and a single clogged weep hole can usually be handled with routine repair and some monitoring. Noticeable lean, an active bulge, movement after a storm, or a wall that supports a driveway, building, or other structure should be evaluated soon. Taller walls and walls carrying significant loads may need an engineered design for repair or replacement, and many cities require permits above certain heights, so check with your city or county before rebuilding.

In the meantime, keep people and vehicles away from a wall that is visibly moving, and avoid adding weight above it. Parking close to the top, stacking materials, or piling extra soil there can push a struggling wall over the edge.

Retaining walls, and the drainage behind them, are part of the flatwork CIMA Concrete builds and repairs around Lockhart and the surrounding area. A site visit can sort out whether a wall needs maintenance, targeted repair, or a rebuild with better drainage and footing.