waterproofing

Basement Waterproofing Cost in 2026: Method, Size & Cause Breakdown

Basement Waterproofing Cost in 2026 Basement waterproofing cost in 2026 runs $500-$2,000 to seal walls with coating, $3,000-$12,000 for an interior drainage system with a sump pump, and $10,000-$40,000 for full exterior excavation. Interior drainage prices at roughly $50-$100 per linear foot of wall; exterior excavation runs $100-$250 per linear foot. The national average for a typical interior system lands around $5,000-$8,000. Price your own job with the Basement Waterproofing Cost Calculator(/construction/basement-waterproofing-cost-calculator) by method, perimeter, and water severity. A 1,100-square-foot basement with about 130 linear feet of wall makes a useful real-world case. Three contractors quoted $4,200, $7,800, and $19,500 for what turned out to be the same seepage problem at the floor-wall joint. The $7,800 interior drainage system, which included a $1,400 sump pump and battery backup, put the drain tile itself at roughly $49 per linear foot. The $19,500 exterior excavation bid would have dug up a patio...