Retaining Walls in McDonough, GA: When a Slope Becomes a Problem

McDonough and Henry County have seen significant new construction over the last decade, and with new construction comes grading -- slopes and cuts that were not there before. Builder grading creates level pads for houses, which often means the adjacent yard is cut or filled at steep angles. Some of those slopes hold fine with grass or erosion matting. Others start shifting, eroding, and sending soil toward the house every time it rains.

If you have a slope on your Henry County property that is causing problems, this article covers how to recognize when a retaining wall is the right solution, what material options make sense in Georgia, and what makes the difference between a wall that lasts and one that fails within a few years.

Signs You Have a Retaining Wall Problem

Not every slope needs a wall. But these are signs that the slope is moving in a way that a wall would address:

• Soil washing down the slope and collecting at the base after rain
• Visible cracks in an existing wall, or the wall is starting to lean forward
• A slope that used to hold grass but is now mostly bare dirt -- bare ground means the roots that were holding the soil are gone
• Water pooling at the base of a slope, near your foundation or driveway
• Erosion that is undercutting a fence line or driveway edge
• A slope that is too steep to mow safely

Any of these indicates the slope is moving -- slowly or quickly -- and will continue to worsen without intervention. The longer you wait on a moving slope, the more soil you lose and the larger the repair job becomes.

Why Georgia Clay Makes Slopes Worse

Henry County's clay soil holds water and becomes unstable when saturated. Clay that looks solid and stable when dry can shift significantly after three or four inches of summer rain. The weight of saturated clay per cubic foot is substantially higher than dry clay -- a slope that is borderline stable when dry may not be when the clay is full of water.

This is also why retaining walls fail most often after periods of heavy rainfall. A wall with no drainage behind it builds up hydrostatic pressure -- the weight of water-saturated clay pressing against the wall face. That pressure, over time or after a significant storm event, pushes the wall forward. It looks like a foundation failure, but the actual cause is water management.

Georgia's piedmont region also has shrink-swell clay behavior: the soil expands when wet and contracts when dry. That repeated movement works at any wall footing that is not set below the active zone. A properly designed wall accounts for this. A wall set in too-shallow ground will creep forward over a few seasons of wet-dry cycles.

Retaining Wall Material Options

The right material depends on the height of the wall, the aesthetics you want, and budget:

• Concrete block (segmental retaining wall block): The most common choice for residential retaining walls in Henry County. Engineered block systems like Allan Block or Versa-Lok are designed to work with drainage aggregate and geogrid reinforcement for taller walls. Cost-effective, durable, and available in multiple finishes. Works well for walls from two to six feet in height.
• Natural stone: More expensive than block but better looking, especially for walls visible from the street, patio, or main living area. Dry-stacked fieldstone gives a traditional Georgia look. Mortared stone is more stable for taller walls. Natural stone walls built by someone who knows what they are doing last for decades.
• Timber (landscape timbers or railroad ties): Appropriate for smaller walls, under three feet, in informal settings. Less expensive than block or stone. Shorter lifespan: pressure-treated timber walls typically last 15 to 20 years before the wood degrades at the soil line. Not appropriate for walls holding significant soil loads.
• Poured concrete: Typically used in commercial applications. Overkill for most residential retaining walls, and more expensive to form and pour than segmental block for the same height. Some homeowners request it for a very clean look, but block accomplishes the same structural function at lower cost.

What Makes a Retaining Wall Last

The wall is holding back soil and water. The water is the critical factor that most failed walls did not account for properly.

• Drainage aggregate behind the face: Crushed stone (typically #57 stone) packed directly behind the wall face creates a free-draining zone that prevents hydrostatic pressure from building up. Without this, water pressure accumulates and eventually pushes the wall forward. This step should be non-negotiable on any wall over two feet.
• Drain pipe at the base: For taller walls or walls holding large soil areas, a perforated drain pipe at the base of the aggregate zone carries water out to daylight at the ends of the wall. The water has to go somewhere -- drain pipe directs it away from the wall rather than letting it pool at the base.
• Proper footing depth: The base course of the wall needs to be set below the frost depth (in Henry County that is relatively shallow) and into stable, undisturbed soil. A wall footing sitting on disturbed fill soil will settle unevenly.
• Batter (backward lean): Block retaining walls are typically built with a slight backward lean into the slope -- one inch of setback per foot of height is the rule for most block systems. This batter uses gravity to counteract the pressure pushing the wall forward.
• Geogrid reinforcement for taller walls: Walls over four feet in height need horizontal layers of geogrid fabric running back into the slope at intervals. The geogrid ties the wall back into the retained soil so the whole system acts as one mass rather than the wall face trying to hold everything alone.

Permit Requirements in Henry County

Walls over four feet in height typically require a building permit in Henry County. The permit process requires engineering documentation for taller walls -- the county wants to see that the wall design accounts for the soil load and drainage. If the wall is near a property line, setback requirements apply as well.

A contractor should pull the permit rather than the homeowner. When the contractor pulls the permit, the liability for the work sits with the contractor. When a homeowner pulls their own permit and hires labor, the liability for the work sits with the homeowner. It is a practical distinction that matters if something goes wrong.

For walls under four feet that do not require permits, proper drainage and base work still matter. A permit exemption does not mean the wall was built correctly -- it just means no inspector looked at it. Do the drainage work regardless of whether a permit is required.