Geogrid

Without geogrid, a retaining wall only has its own weight and the friction under its base to resist the soil pushing on it, which limits how tall it can safely go before the design becomes impractical. Geogrid layers extend out into the backfill at set intervals as the wall rises, locked into the wall face at one end and buried in compacted soil at the other. That anchors a much larger volume of soil behind the wall, so the reinforced soil mass, not just the wall itself, is what resists the lateral pressure pushing against it.

Geogrid only works if the backfill around it is compacted the way it's supposed to be and drains properly, layer by layer as the wall goes up. Loose fill or waterlogged soil doesn't grip the mesh the way compacted, well-draining material does, and that matters more here than in a drier climate because Blue Ridge soil holds onto moisture through a long freeze-thaw season. That's why getting the backfill right around each layer is as important to a geogrid wall's long-term performance as the geogrid itself.