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Landscaping with wood is a green sustainable solution for the future. As such, wood is increasingly specified in projects by sustainability experts, engineers, architects, and landscaping professionals.
According to Forestry South Africa, less than 10% of the country’s total plantation area of 1.2 million hectares is harvested annually. Felled trees are replaced in the same year by saplings, often at a ratio of 2:1. This means there is a constant supply of trees for productive purposes for years to come.
South Africa’s plantations remove a significant amount of carbon dioxide from the atmosphere during their rotations of 7-20 years.All timber products – whether a timber pole, a plank, plywood or cross-laminated timber – keep the carbon locked up.
Treated timber in South AfricaÂ
The biological deterioration of timber by insect attack (wood borer and termites) and fungal decay (rot) is a problem that historically has been solved by treating wood with chemicals.Â
CCA is one of the world’s most widely uses wood preservatives and has been used in South Africa since the early 1930s.
What is CCA? Â
CCA is the abbreviation for Chromated Copper Arsenate.Â
CCA contains compounds of 47.5% chromium (CrO3), 18.5% copper (CuO), and 34.0% arsenic (As2O5).
Each of the three elements in the mix serve a certain purpose:
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In South Africa, CCA Type C is used as it is internationally recognized as the most stable and effective type, i.e., apart from its efficacy as a timber preservative.
You can only CCA to timber using industrial high-pressure processes from where the familiar term ‘pressure-treated wood’ is derived.Â
The manufacture and distribution of CCA is regulated by the Registrar Act 36 of 1947 and it is registered as an agricultural remedy under the category ‘Wood Preservative’.
Brochure: South African Wood Preservers Association – Guide to CCA-Treated Timber
Fact Sheet:Â Â CCA Treated Timber in South Africa
The preservation process of wood
The CCA process was pioneered in 1933 and is used worldwide. Copper and arsenic in the preservative protect the wood from insect and fungal attack. Chromium (chrome) ‘locks’ the copper and arsenic into the timber and reduces the risk of the chemicals leaching out.
The CCA process gives the treated wood a green tint.
Arsenic
The main concern with CCA-treated timber is that it contains arsenic, which can be ingested (swallowed) or inhaled (when CCA-treated timber is burnt).
Over time, small amounts of chemicals may leach from CCA-treated timber, but research has found that the amount of leached arsenic is less than that found in common foods.
Since the general population is exposed to naturally occurring arsenic in soil, water and food, the human body can tolerate small amounts of arsenic.
What is CCA used for in South Africa?
In South Africa, CCA is used as an industrial wood preservative as stipulated by the National Regulator for Compulsory Specifications (NRCS) approved and SABS or SATAS-certified industrial wood preservation plants, i.e., under-regulated and controlled conditions.
CCA Treated Timber is governed by the Department of Trade and industry.
There are different hazard classifications, ranging from H2 (dry interior above ground) to H5 (heavy wet soils and freshwater), and for H6 (Marine contact) when used as a dual treatment with Creosote.
CCA Treatment has different hazard classes:
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Identifying CCA Treated Timber
You can identify CCA Treated Timber by its yellow/greenish to green colour that fades over time into a weathered silver-grey if exposed to the elements and not maintained with wood finishing protective product i.e., a suitable exterior sealer.
Booklet: South African Wood Preservers Association – Understanding Wood Preservation
International concerns about CCA Treated Timber
Concerns have been raised regarding the potential health risks of CCA Treated Timber.
Although the chemicals are fixed within the dry wood in CCA-treated timber, concerns have been expressed internationally about the potential for harm as small amounts of arsenic can leach out of the surface of the timber.
US and Canada
The US and Canada jointly decided to restrict the use of CCA Treated Timber in non-industrial settings after January 2004. EPA 2004.
European Union
Regulatory agencies in the European Union prohibit CCA Treated Timber in residential uses, while considering that timber already in place need not be replaced.
New Zealand
In 2003, New Zealand’s Environmental Risk Management Authority decided to not restrict CCA use for any applications but notes that few well-designed studies have been carried out of those using CCA or CCA Treated Timber.
Australia
In March 2005, the Australian Pesticides and Veterinary Medicines Authority (APVMA) reviewed the safety of CCA Treated Timber use in Australia.
In Australia, the recommendation is that CCA Treated Timber …
What alternatives are there to CCA?
According to the South African Wood Preservers Association, alternative products are available, but they are either less practical or in some cases less effective in certain high hazardous and critical end applications, not always readily available, and in some cases just too costly when compared with other competing materials.
The alternatives to CCA for applications ranging from H2 (dry interior above ground) to H5 (contact in fresh water) hazard end applications are:
– Creosote, which is well known and extensively used since 1832, however its aromatic and oily characteristics renders it more practical for industrial and agricultural end uses, e.g. fencing, transmission and telephone poles, railway ties, etc. where direct contact and extended close proximity is not expected. When used together with CCA as a dual treatment it is suitable for H6 (marine) applications in South African coastal waters.
– The new generation inorganic alternatives used in applications similar to CCA are Copper Azole (CuAz), and Alkaline-Copper Quaternary (ACQ) preservatives. These preservatives are new to South Africa and therefore not widely available.
CCA vs Creosote evaluation has been undertaken by SAWPA.
For more information please contact:
South African Wood Preservers Association (SAWPA)
T: 011 974 1061
E: admin@sawpa.co.za
W: www.sawpa.co.za
