Introduction: Fraser Valley's Biggest Roofing Problem

Moss and algae thrive in Fraser Valley's wet climate. Left untreated, moss lifts shingles, holds moisture, and reduces roof lifespan by 30-50%. This guide covers safe removal methods and prevention strategies.

UNDERSTANDING MOSS VS. ALGAE

Moss (The Serious Problem)

What It Is:

• Green, thick, spongy plant growth
• Grows in clumps, spreads slowly
• Has roots that penetrate shingles
• Holds moisture like a sponge

Why It's Damaging:

• Lifts shingles: Roots grow under edges, creating gaps
• Holds moisture: Keeps shingles wet, accelerates rot
• Blocks drainage: Water backs up under shingles
• Adds weight: Heavy when wet
• Reduces lifespan: 30-50% shorter lifespan

Algae (Cosmetic Issue)

What It Is:

• Black streaks on roof (Gloeocapsa magma)
• Thin, flat growth
• Feeds on limestone in shingle granules
• Spreads quickly

Why It's Less Damaging:

• Mostly cosmetic: Ugly but doesn't lift shingles
• Reduces reflectivity: Dark streaks absorb heat
• Lowers curb appeal: Makes roof look old/dirty

WHY FRASER VALLEY HAS SO MUCH MOSS

Perfect Conditions

Climate Factors:

• High rainfall: 170+ cm per year
• Mild temperatures: Ideal for moss growth (5-25°C)
• High humidity: Keeps moss moist
• Overcast days: Moss prefers shade

Roof Factors:

• North-facing slopes: Less sun, stay wet longer
• Tree coverage: Shade + falling debris
• Low-slope roofs: Water drains slowly
• Older shingles: Rougher surface, easier for moss to grip

MOSS REMOVAL METHODS

Method 1: Soft Wash (BEST - Professional)

What It Is:

• Low-pressure chemical treatment
• Kills moss at roots
• Safe for shingles
• Moss dies and washes away over 2-4 weeks

Process:

• Step 1: Apply moss-killing solution (sodium hypochlorite or zinc sulfate)
• Step 2: Let sit 15-30 minutes
• Step 3: Rinse with low-pressure water
• Step 4: Moss dies, turns brown, washes off in rain

Pros:

• Safe for shingles (no damage)
• Kills moss at roots (longer-lasting)
• Treats algae too
• Professional results

Cons:

• Requires professional equipment
• Chemical handling
• Cost: $1-2 per sq ft ($1,000-2,000 for typical roof)

Method 2: Manual Removal (DIY - NOT RECOMMENDED)

What It Is:

• Scraping/brushing moss off
• Using stiff brush or scraper

Why We Don't Recommend:

• Damages shingles: Removes granules, shortens lifespan
• Doesn't kill roots: Moss regrows within months
• Dangerous: Wet moss is slippery
• Time-consuming: Hours of work

If You Must Do It:

• Use soft-bristle brush (not wire brush)
• Brush downward only (with shingle direction)
• Don't scrape aggressively
• Wear safety harness

Method 3: Pressure Washing (NEVER DO THIS)

Why Pressure Washing Destroys Roofs:

• Removes granules: Exposes asphalt mat, voids warranty
• Damages shingles: High pressure tears fiberglass mat
• Forces water under shingles: Creates leaks
• Shortens lifespan: By 50% or more

NEVER pressure wash your roof. It will cause more damage than the moss.

ALGAE REMOVAL

Chemical Treatment (Best Method)

DIY Solution:

• Mix: 1 part bleach (sodium hypochlorite) to 1 part water
• Apply: Spray on algae streaks
• Wait: 15-20 minutes
• Rinse: Low-pressure garden hose

Safety:

• Wear gloves, eye protection
• Protect plants (cover with tarp, rinse after)
• Don't mix bleach with other chemicals
• Work on cloudy day (sun evaporates solution too fast)

Professional Treatment:

• Stronger solutions
• Better coverage
• Cost: $500-1,000 for typical roof

PREVENTION STRATEGIES

Zinc Strips (Most Effective)

How They Work:

• Install zinc strips at ridge
• Rain washes zinc ions down roof
• Zinc inhibits moss/algae growth
• Protects 10-15 feet below strip

Installation:

• Location: Just below ridge cap
• Coverage: One strip per 10-15 feet of roof width
• Cost: $3-5 per linear foot installed
• Lifespan: 10-15 years

Effectiveness:

• Reduces moss growth by 80-90%
• Doesn't eliminate moss entirely (still need periodic cleaning)
• Works best on upper roof sections

Copper Strips (Alternative)

Similar to Zinc:

• Copper ions inhibit moss/algae
• More expensive than zinc
• Longer lifespan (20+ years)
• Cost: $5-8 per linear foot

Algae-Resistant Shingles

What They Are:

• Shingles with copper granules embedded
• Copper inhibits algae growth
• Available from all major manufacturers

Brands:

• GAF: StainGuard Plus (10-year algae warranty)
• IKO: ArmourZone (10-year algae warranty)
• Owens Corning: StreakGuard (10-year algae warranty)
• CertainTeed: StreakFighter (15-year algae warranty)

Effectiveness:

• Prevents algae for 10-15 years
• Less effective against moss (moss is more aggressive)
• Cost: $50-100 more per square (minimal)

Tree Trimming

Why It Helps:

• More sunlight = less moss
• Less debris = cleaner roof
• Better airflow = faster drying

How Much to Trim:

• Keep branches 6-10 feet from roof
• Trim overhanging branches
• Remove dead branches (fall on roof)

Regular Cleaning

Frequency:

• Heavily shaded roofs: Every 1-2 years
• Moderate shade: Every 2-3 years
• Full sun: Every 3-5 years (or as needed)

Why Regular Cleaning Matters:

• Easier to remove when moss is thin
• Less damage to shingles
• Prevents moss from lifting shingles
• Extends roof lifespan

COST COMPARISON

Moss Removal Costs (Fraser Valley, 2026)

Professional Soft Wash:

• Small roof (1,500 sq ft): $1,500-2,500
• Medium roof (2,500 sq ft): $2,500-4,000
• Large roof (4,000 sq ft): $4,000-6,000
• Per sq ft: $1-2

DIY Costs:

• Moss killer solution: $50-100
• Pump sprayer: $30-80
• Safety equipment: $100-300 (harness, rope)
• Total: $180-480 + your time/risk

Prevention Costs

Zinc Strips:

• Materials: $50-150 (typical roof)
• Installation: $200-400 (professional)
• Total: $250-550
• Lifespan: 10-15 years

Algae-Resistant Shingles:

• Upgrade cost: $50-100 per square
• Typical roof: $500-1,000 total upgrade
• Only during re-roof

MOSS DAMAGE: WHEN TO REPLACE ROOF

Signs Moss Has Caused Serious Damage

Inspect For:

• Lifted shingles: Edges curled up from moss roots
• Missing granules: Bare spots where moss grew
• Cracked shingles: Brittle from constant moisture
• Soft deck: Rot from prolonged moisture
• Leaks: Water infiltration from lifted shingles

Decision Matrix:

• Light moss, no damage: Clean and prevent
• Heavy moss, minor damage: Clean, repair damaged sections
• Heavy moss, widespread damage: Replace roof

The Bottom Line

Moss is Fraser Valley's biggest roofing enemy. Regular cleaning (every 2-3 years) and prevention (zinc strips, tree trimming) extend roof lifespan by decades. Never pressure wash - it causes more damage than moss.

At RJ Roofing Bros, we offer professional soft-wash moss removal using safe, effective solutions. We also install zinc strips during re-roofs and recommend algae-resistant shingles. We've cleaned hundreds of Fraser Valley roofs and know how to do it safely without damaging your shingles.

Need moss removal? Call (604) 997-1292