2026 cost reference
Interior and exterior systems are not interchangeable
Interior perimeter drains manage water after it reaches the foundation and usually involve cutting the basement slab. Exterior footing drains require excavation and address water before it enters the wall.
The cheapest waterproofing quote can be a different scope
One proposal may be paint or crack sealing while another includes a full perimeter drain, sump basin, pump and discharge line. Compare system components before comparing totals.
Finished basements need a second budget
Drywall, flooring, trim, mold remediation and finish restoration are intentionally excluded from the drainage calculator unless they are measured separately. That avoids pretending a generic finish allowance fits every basement.
The calculator uses the same reviewed source ranges shown on this page.
These figures may be quoted with attribution and a link. Review date: August 29, 2026.