A Guide to Creosote and CCA for Different Wood Types in SA
South Africa's beautiful climate can be harsh on untreated wood. Fungal decay and insect damage quickly compromise the integrity and lifespan of wooden structures. To combat these threats, treated timber plays a vital role in construction and landscaping projects. This guide explores the two main types of treatments used in South Africa: Creosote and CCA (Chromated Copper Arsenate). We'll delve into their properties, applications, and suitability for different softwood and hardwood species commonly used in the country.
Part 1: Creosote Treatment
What is Creosote?
Creosote is a dark, oil-based preservative derived from coal tar. During the high-temperature distillation of coal, creosote condenses as a by-product.
Properties of Creosote-treated Wood:
Creosote offers excellent benefits:
High Durability: It provides long-lasting protection against fungal decay and insect attack.
Water Repellency: Creosote effectively repels water, making it ideal for outdoor applications.
Resistance to Decay and Insects: The oil-based nature discourages fungal growth and deters insects like termites and borers.
However, there are downsides:
Strong Odor: Creosote has a distinct, tar-like odor that can be unpleasant.
Black Color: The treatment imparts a deep black color to the wood, limiting aesthetic options.
Environmental Concerns: Leaching of creosote components raises environmental concerns.
Applications of Creosote-treated Wood:
Creosote is ideal for outdoor and high-moisture environments:
Fence Posts: Pressure-treated pine fence posts benefit from creosote's durability and water repellency.
Marine Pilings: Saligna gum pilings treated with creosote offer excellent resistance to saltwater and marine organisms.
Suitable Softwood and Hardwood Types for Creosote Treatment:
Softwoods like pine, fir, and spruce readily absorb creosote due to their high porosity. Hardwoods generally have lower absorption rates, but some eucalyptus species like treated gum poles can be used for fence posts where aesthetics are less critical.
Part 2: CCA Treatment
What is CCA?
CCA, or Chromated Copper Arsenate, is a waterborne wood preservative containing copper, chromium, and arsenic. These elements work synergistically to protect the wood.
Properties of CCA-treated Wood:
CCA offers several advantages:
Protection against Decay and Insects: Like creosote, CCA protects against fungal decay and insect infestations.
Lighter Color: Compared to creosote, CCA-treated wood retains a greenish tint, allowing for staining or painting.
Potential for Above-ground Applications: CCA can be suitable for some above-ground applications with proper handling.
However, environmental concerns exist due to the presence of arsenic.
Applications of CCA-treated Wood:
CCA is well-suited for various outdoor structures:
Decking: CCA-treated pine decking offers dimensional stability and resists decay.
Fencing: Saligna gum treated with CCA provides durable fencing for outdoor spaces.
With proper handling, CCA can be used for some above-ground applications:
Furniture: CCA-treated meranti can be used for outdoor furniture after proper finishing to prevent contact with the treated wood.
Important Note: CCA-treated wood should not be used in direct contact with soil or water due to potential leaching of arsenic.
Suitable Softwood and Hardwood Types for CCA Treatment:
Softwoods like pine, fir, and spruce are ideal for CCA treatment due to their porosity. Modified CCA formulations can be used for some hardwoods like saligna gum or meranti, offering a lighter-colored alternative to creosote for specific applications.
Part 3: Making the Right Choice:
Application: Consider the location and purpose. Creosote is ideal for high-moisture environments, while CCA can be used for some above-ground applications.
Aesthetics: CCA offers a lighter color that can be further enhanced with paint or stain.
Environmental Considerations: If environmental impact is a major concern, CCA might be a better choice due to stricter regulations around arsenic usage.
Conclusion
Understanding wood treatments and wood types is crucial for making informed decisions about your project. By considering the factors discussed above, you can choose the right treated timber for your needs in South Africa. Remember, always follow safety guidelines when handling and using treated wood to ensure a successful and lasting project.
