Waterproofing Cost

What We Know About Waterproofing Cost

• According to recent cost guides, waterproofing a retaining wall typically runs about $2 to $10 per square foot of wall surface.
• A key point: the waterproofing cost is in addition to the base cost of building the wall.
• For Southern California, base build costs for retaining walls (concrete, poured, etc.) are in the range of roughly $45–$55 per sq ft for modest walls (~3 ft high) in the LA area.

Estimate for your situation

Since you’re in the piles/drilling/shoring business working in the Altadena/Pasadena region, and may deal with higher walls, challenging soils, etc, here’s a sense of what you might budget:

• Suppose you have a retaining wall 6 ft high, 100 ft long ? wall face area = 6 × 100 = 600 sq ft.
• Waterproofing portion (at $2–10/sq ft) = $1,200 to $6,000.
• If the base wall build cost is more challenging (say $50–$70/sq ft given terrain, height) ? wall build cost = 600 × $50–70 = $30,000 to $42,000.
• Combined: you might be looking at ~$31,200 to $48,000 for that wall (base build + waterproofing) excluding any major geotechnical surprises, site-access premium, ties/backfill, etc.
• If wall height or complexity goes up (10 ft height, hillside, fire-damaged site, etc.), costs scale upward significantly.

Key factors that will drive cost (and things to watch)

• Height & length of wall: Taller walls require deeper foundations, more reinforcement, more backfill, and drainage.
• Soil & site conditions: Post-fire sites (you specialize in fire restoration drilling/shoring) often have disturbed soils, slopes, and access issues — all increase cost.
• Drainage & waterproofing system: Ensuring water doesn’t build up behind the wall is critical — good drainage and waterproofing will extend the life of the wall. Guides note that waterproofing is important for lifespan.
• Access/terrain: Hillsides, remote spots, and fire-affected sites often increase labor, equipment cost, and mobilization.
• Permits & engineering: In California, walls above a certain height require engineered design; that adds cost.
• Finishes / specialty materials: If the wall includes face veneer, decorative finishes, or curves, cost per sq ft increases.
• Removal of existing structure / remediation: If you’re replacing or reinforcing an existing wall, costs increase.