Drainage is the whole job
Hydrostatic pressure behind a wall is what pushes it over. A proper build has free-draining gravel backfill, a perforated drain pipe daylighting to a low point, and filter fabric to keep soil out of the gravel.
- • Terracing two 3 ft walls can be cheaper than one 6 ft engineered wall.
- • Geogrid reinforcement is required on most block walls above 4 ft.
- • Slope the finished grade away from the wall crest.
FAQ
How much does a retaining wall cost per foot?
Most residential block walls run $40–90 per linear foot at 2–4 ft tall, rising to $150–350 per linear foot for engineered walls 6 ft and above.
Do I need a permit for a retaining wall?
Typically yes at 4 ft measured from the bottom of the footing, or at any height if the wall supports a surcharge like a driveway or structure.
What's the cheapest retaining wall material?
Pressure-treated timber is cheapest up front but lasts 15–20 years. Segmental concrete block costs more and lasts 50+, which usually wins on lifetime cost.
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