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Cedar Shake
Roof Preservation

Soy-Based Oil Treatment for Cedar Roof Longevity
 

Cedar shake roofs are a natural, durable roofing system—but only when they are properly maintained. Over time, exposure to sun, wind, and moisture causes cedar to dry out, lose oils, and become brittle, increasing the risk of splitting, cupping, and premature failure.
 

At The Great Canadian Roof Doctor Inc., cedar shake preservation is approached with the same inspection-first discipline we apply to all roofing systems. When a cedar roof is structurally sound, a soy-based oil preservation treatment can help restore moisture balance and slow natural deterioration.

What Cedar Shake Preservation Is — and Isn’t

Cedar shake preservation is a maintenance treatment, not a repair or replacement.

It is designed to:

  • Reintroduce oils to dried cedar shakes

  • Reduce brittleness and splitting

  • Slow weathering and surface checking

  • Support long-term performance between inspections

It is not:

  • A fix for rotting or failed shakes

  • A solution for structural or underlayment issues

  • A guarantee against leaks

  • Appropriate for roofs at end of life

As with any roofing system, condition—not age—determines suitability.

Why Cedar Roofs Dry Out

Cedar is a natural wood product that relies on internal oils to remain flexible and resilient. Over time, these oils are depleted by:

  • UV exposure

  • Wind and weather

  • Freeze-thaw cycles

  • Coastal moisture followed by drying

Once cedar becomes overly dry, it is more prone to:

  • Cracking and splitting

  • Curling and cupping

  • Accelerated water intrusion

  • Shortened service life

Preservation focuses on slowing this process, not reversing damage.

Our Inspection-First Approach to Cedar Preservation

Before recommending any treatment, we perform a professional roof inspection to confirm the roof is a candidate for preservation.

We assess:

  • Overall condition of cedar shakes

  • Signs of rot or advanced decay

  • Fastener performance

  • Roof deck integrity (when accessible)

  • Flashing, valleys, and penetrations

  • Drainage and moisture exposure

If a cedar roof does not qualify, preservation will not be recommended.

Proper Preparation Is Critical

Before applying a soy-based oil treatment:

  • The roof is carefully cleaned using low-pressure, wood-safe methods

  • Moss, algae, and organic buildup are removed

  • The cedar is allowed to dry to appropriate moisture levels

Applying oil to a dirty or improperly prepared roof reduces effectiveness and can trap moisture where it doesn’t belong.

How Soy-Based Oil Helps Cedar Shakes

Soy-based oil treatments are designed to:

  • Penetrate cedar fibers

  • Restore lost oils gradually

  • Improve flexibility and resilience

  • Reduce rapid moisture cycling

Unlike surface sealers or film-forming coatings, soy-based oils are intended to condition the wood, not encapsulate it.

This helps cedar behave more like it did earlier in its service life.

Important Limitations to Understand

Even on a qualifying cedar roof, preservation has limits.

Cedar preservation does not:

  • Repair damaged or rotted shakes

  • Correct improper installation

  • Replace underlayment

  • Eliminate leak risk at flashings or penetrations

Leaks can still occur at:

  • Chimneys

  • Skylights

  • Valleys

  • Roof transitions

  • Fasteners

Some deficiencies can only be identified through destructive testing, which involves temporarily removing shakes to inspect the system below. Most inspections and preservation work remain non-destructive.

Cedar Shake Preservation vs. Replacement

Preservation is intended to:

  • Extend service life responsibly

  • Reduce unnecessary tear-offs

  • Support long-term planning

It is not intended to delay replacement indefinitely. When a cedar roof reaches true end of life, replacement is the responsible option.

A well-maintained cedar roof, however, can often remain serviceable well beyond its expected lifespan.

Cedar Roofs on Vancouver Island

Cedar shake roofs in Victoria, Saanich, Langford, Nanaimo, Duncan, and across Vancouver Island face unique challenges:

  • High moisture levels

  • Moss and organic growth

  • Coastal weather exposure

  • Seasonal drying cycles

Our preservation recommendations are based on local experience, not generic treatment schedules.

Is Cedar Shake Preservation Right for Your Roof?

Cedar preservation is not for every roof—and it should never be applied automatically.

If you want clear answers, honest expectations, and responsible recommendations, the first step is a professional inspection.

Request a Cedar Roof Inspection

Serving Victoria BC & Vancouver Island · Inspection-First Roofing

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