Stucco is one of the most popular exterior finishes in the GTA — from 1950s bungalows with traditional cement stucco to 2000s-era homes with EIFS (synthetic stucco). Both get dirty. Both grow algae. Both need cleaning. But the method is completely different, and using the wrong one destroys the wrong type.
The Two Stuccos — Know Your Type
🧱 Traditional Stucco
- Cement, sand, and lime mixture
- Hard — sounds solid when tapped
- Common on homes built before 1990
- Typical Toronto bungalows and older homes
- Cracks develop over time (normal)
- Can be pressure washed at 1,000-1,500 PSI
- Textured surface traps dirt, algae, and pollution
🏗️ EIFS / Synthetic Stucco
- Foam insulation board with thin acrylic finish
- Hollow — sounds hollow/drum-like when tapped
- Common on homes built after 1990
- Custom homes, tract housing, additions
- Smooth or light texture finish
- SOFT WASH ONLY — NO pressure
- Finish is only 3-5mm thick over foam
The $50,000 mistake: Pressure washing EIFS at standard PSI (2,000-3,000) punches through the thin acrylic finish coat and into the foam insulation layer. Water enters behind the finish, gets trapped, and creates a mould factory inside your walls. Symptoms appear 6-18 months later: bubbling finish, black mould spots, mushy walls, rotten framing. Remediation for EIFS water damage: $10,000-$50,000+ depending on how far the moisture spread. Many Toronto homeowners don't know they have EIFS until damage appears. The tap test takes 3 seconds and saves thousands.
Cleaning Methods
For traditional stucco:
- Pre-treat algae and mould spots with oxygen bleach solution (NOT chlorine bleach — damages colour)
- Let dwell 10-15 minutes
- Pressure wash at 1,000-1,500 PSI, 40° nozzle, 24+ inches distance
- Work in 4-foot sections, bottom-up, rinse top-down
- Avoid concentrating spray on cracks — water drives INTO cracks and behind the stucco
- Extra attention to north-facing walls (most algae growth)
For EIFS/synthetic stucco:
- Apply biodegradable soft wash solution with low-pressure sprayer (<500 PSI)
- Let dwell 15-20 minutes — the solution does the cleaning, not pressure
- Gentle rinse with garden hose pressure or low-pressure wide spray
- NEVER use turbo nozzle, 0° nozzle, or any pressure above 500 PSI
- Avoid spraying upward under horizontal joints — drives water behind panels
Toronto-Specific Stucco Problems
- Green algae (north face): Toronto's humid springs + 80+ freeze-thaw cycles = perfect algae conditions. North-facing stucco gets minimal sun, stays damp, and grows green algae within 2-3 years. Annual cleaning prevents permanent staining.
- Efflorescence (white powdery deposits): Common on traditional stucco. Mineral salts leach through the cement as water evaporates. Not harmful but unsightly. Cleaning removes it but it may return until the stucco fully cures (can take years).
- Hairline cracks: Normal on traditional stucco — caused by thermal expansion. Clean AROUND cracks, not INTO them. Seal cracks with elastomeric caulk after cleaning.
- Rust stains: Metal flashing, nails, or rebar touching stucco creates orange rust streaks. Requires oxalic acid treatment, not just pressure. Common on older Scarborough and North York homes.
- Road salt staining: Lower portions of stucco facing driveways and roads get salt splash. ClearCoat™ purified water dissolves salt without leaving mineral deposits that bond with stucco texture.
Cost Guide
- Traditional stucco pressure wash: $300-$700 (most homes)
- EIFS soft wash: $400-$900 (20-30% premium for solution + dwell time)
- As part of full exterior package: Usually included in complete exterior wash
- MANTLE: Stucco walls included in all exterior pressure washing packages. We identify your stucco type before cleaning.
The colour restoration effect: Dirty stucco fades 2-3 shades darker over time as grime accumulates in the textured surface. Professional cleaning restores the original colour — homeowners are often shocked at how bright their stucco was supposed to be. This colour restoration alone can make a 20-year-old home look 5 years old. Combined with clean windows and a clean driveway, the transformation is dramatic.
Get Your Stucco Cleaned Safely
We identify your stucco type first. Traditional = pressure. EIFS = soft wash. Never guessing.
Get Free Estimate →Or call (416) 206-3274
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