The answer to how much a retaining wall costs in Illinois can vary widely, but typically ranges from $30 to $100 per square foot installed. The exact cost will depend on factors like the size and height of the wall, the materials used (e.g. concrete, stone, timber), site conditions, and the complexity of the installation.
Larger or more complex retaining walls at the higher end of the cost range may require engineering design, extensive excavation, and specialized equipment. Simpler walls using basic materials like concrete blocks or treated lumber can be at the lower end. It's important to get multiple quotes from local landscaping companies to understand the costs in your specific area.