Can I use this calculator for a renovation or only for new construction?

The calculator is built around new construction assumptions, foundation, structure and finishing from scratch, and it will not reliably estimate renovation work where demolition, partial retention of existing structure and matching old finishes all add cost that a new-build model does not capture. For renovation or extension work, a site-specific assessment is more useful than adapting this tool's output. Contact us directly with photos and a description of the scope if you are renovating rather than building fresh.