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Cedar Shake Roof Cleaning, Treatment & Maintenance Guide (PNW 2026)

  • Writer: Ryan Michael
    Ryan Michael
  • 7 days ago
  • 3 min read

Cedar shake roofing is one of the most beautiful and durable roofing systems in the Pacific Northwest—but it requires the right care to last. With constant moisture, moss growth, and seasonal weather shifts, maintenance isn’t optional here—it’s essential.

In this guide, we’ll break down everything homeowners in Washington need to know about cleaning, treating, and maintaining cedar shake roofs—plus how to protect your investment for decades.




Why Cedar Shake Roofs Are So Popular in Washington


Cedar shake roofs have been a staple in the PNW for generations. They’re made from natural western red cedar and offer:

  • Natural beauty that ages into a silver-gray patina

  • Built-in insulation for year-round comfort

  • Strong durability when properly maintained


A well-maintained cedar roof can last 25–50 years, making it a long-term investment for homeowners.



The Biggest Threats to Cedar Roofs in the PNW


The same climate that makes Washington beautiful also creates serious challenges for cedar roofs.


Moss & Algae Growth


Moisture and shade allow moss to thrive, trapping water against the wood and accelerating decay.


Moisture Retention & Rot


Wet cedar softens over time, leading to internal rot and structural issues.


UV Damage & Cracking


Seasonal drying causes expansion and contraction, leading to splits and curling.


Loss of Natural Oils


Cedar loses its protective oils over time, making it more vulnerable to damage.


Why Cleaning & Treatment Matters


Many homeowners wait too long to maintain their roof—but by then, costs can skyrocket.


Proper maintenance helps:

  • Extend lifespan by 10–20 years

  • Prevent expensive repairs

  • Maintain curb appeal

  • Protect structural integrity


Replacing a cedar roof can cost $30,000–$50,000, so proactive care is far more cost-effective.



Best Cedar Shake Cleaning & Treatment Products


Not all products do the same job—here’s how the main ones work:


Wash Safe Cedar Wash (Cleaner)

  • Removes moss, algae, and mildew

  • Safe for plants and does not require pressure washing

  • First step in any maintenance process


CopperCat (Biological Protection)

  • Prevents moss and algae regrowth

  • Provides multi-year protection

  • Best for shaded or north-facing roofs


Messmer’s UV Plus (Oil + UV Protection)

  • Restores cedar’s natural oils

  • Protects against sun damage

  • Improves color and appearance


TWP 100 Series (Full Protection)

  • Oil-based preservative

  • Protects against moisture, UV, and mildew

  • Ideal for long-term restoration


TWP 1500 Series (Low-VOC Option)

  • Same protection as TWP 100

  • More environmentally friendly

  • Compliant with stricter regulations



Recommended Cedar Roof Maintenance Process


A proper maintenance system follows a step-by-step approach:


1. Inspection

Look for moss, cracks, debris, or damaged shakes.


2. Cleaning

Apply a cedar-safe cleaner like Wash Safe (never pressure wash).


3. Biological Protection

Use CopperCat to prevent regrowth.


4. Oil Treatment

Apply Messmer’s or TWP to restore and protect the wood.


5. Ongoing Maintenance

Repeat on a regular schedule to prevent buildup.



How Often Should You Maintain a Cedar Roof in Washington?


In the PNW, timing matters more than in dry climates:

  • Every year: Visual inspection

  • Every fall: Clean gutters and debris

  • Every 2–3 years: Cleaning

  • Every 3–5 years: Full treatment

  • As needed: Repairs


Homes with heavy tree coverage or north-facing roofs may need more frequent maintenance.



Signs Your Cedar Roof Needs Attention


Watch for these warning signs:

  • Moss, algae, or discoloration

  • Curling or lifting shakes

  • Cracks or splits

  • Dark streaking

  • Missing or rotting shakes

  • Interior leaks or water stains


If you notice these, it’s time to act quickly.



DIY vs Professional Cedar Roof Maintenance


When DIY Might Work

  • Single-story homes

  • Light moss or minor cleaning

  • Preventative maintenance


When to Call a Professional

  • Steep or multi-story roofs

  • Heavy moss or widespread damage

  • Missing or rotting shakes

  • Signs of leaks or structural issues


⚠️ Important: Pressure washing can damage cedar and should be avoided.



HOA Considerations for Cedar Shake Roofs


If you live in an HOA community, maintenance is even more important.


Most HOAs require:

  • Keeping cedar roofs clean and well-maintained

  • Replacing cedar with cedar (or approved alternatives)

  • Approval before major repairs or replacement


Common violations include:

  • Heavy moss buildup

  • Discoloration or streaking

  • Patchy repairs

  • Neglected appearance


Staying proactive helps you avoid fines and protects property value.



Final Thoughts


Cedar shake roofs are built to last—but only if they’re properly maintained.


The homeowners who get the most life out of their roofs are the ones who:

  • Stay proactive

  • Follow a maintenance schedule

  • Address issues early


A little attention today can save tens of thousands of dollars down the road.



📍 Need Help With Your Cedar Roof?


If you’re not sure where your roof stands, the best first step is a professional inspection.


Legacy Exteriors can help you:

  • Evaluate your roof condition

  • Recommend the right treatment plan

  • Keep your roof compliant and protected


👉 Request your free roof evaluation today

 
 
 

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