The Appeal and Vulnerability of Western Red Cedar
Western Red Cedar is the timber of choice for architectural homes in Lake Tarawera and Lake Okareka. Its natural resistance to rot and exceptional thermal insulation make it ideal for Rotorua’s climate. However, cedar is biologically reactive to UV light. Prolonged exposure to the sun degrades the lignin—the natural glue holding wood fibres together—causing the surface to turn silver-grey and eventually erode (fibrillation).
Penetrating Oils: The Purist’s Choice
Penetrating oils (such as Dryden WoodOil) sink deep into the timber, replacing the natural oils lost to heat and evaporation.
Pros
- Enhance the natural grain and never peel or flake because there is no surface film.
- Maintenance is simple: a wash and a re-coat.
Cons
- Require more frequent maintenance (typically every 2–3 years) as the oil dissipates.
- Without pigment they offer little UV protection, so a “colour tone” must be added to prevent silvering.
Film-Forming Stains: Enhanced Durability
Stains (such as Resene Woodsman) contain binders that form a semi-transparent film on top of the wood, similar to a thin paint.
Pros
- Provide a physical barrier against moisture and higher UV protection, allowing longer maintenance intervals (4–6 years).
Cons
- Eventually the film will fail. If neglected, it can flake or peel, requiring laborious sanding or stripping before re-coating.
- They obscure some of the natural timber grain.
The Restoration Process
Restoring neglected, silvered cedar requires a delicate touch. Aggressive water blasting raises the grain and ruins the timber’s finish. A professional exterior painting specialist uses a sodium percarbonate (oxygen bleach) solution. Unlike chlorine bleach, which damages wood fibres, oxygen bleach gently lifts the grey, oxidised lignin and kills mould spores without harming the timber’s integrity. Once cleaned and dried to below 16% moisture content, the timber is ready for coating. For lakeside properties, where humidity is high, we often recommend migrating oils as they allow the timber to “breathe” and move with thermal expansion without cracking a surface film.
Conclusion
Cedar is a high-performance material that demands high-performance care. The choice between oil and stain depends on the owner’s aesthetic preference and willingness to undertake regular maintenance. By understanding the chemistry of these products, homeowners can ensure their lakeside retreat remains a stunning example of natural architecture.
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