James Hardie Siding Average Costs. The actual cost of James Hardie siding may vary based on the materials used, the local economy, the complexity of the installation, and other factors. 1  James Hardie siding costs $8 to $12 per square foot.ames Hardie Siding Installation Prices. James Hardie pioneered the use of fiber cement siding in the mid 1980s and today, the material is as popular as it s ever been.