Protect your wood

While we all appreciate the luxury of wood, we don’t always realize that an attack on wooden items might be imminent. Be aware of insects, termites and fungi. If it’s not your wooden furniture then it might be the kitchen cupboards or even structural elements such as roof trusses.protecting wood Sealers and or varnishes are designed to protect against weathering agents, but are not always enough to protect the wood from insects or fungi. Sealers penetrate into the top layer of wood, while varnishes form a protective layer on top of harder woods. Varnishes and sealers are biodegradable and therefore need reapplication regularly as part of your maintenance routine. They can also only be applied to areas that can be seen, while areas like the structure supports underneath your deck, your lapa and other wood continue to be exposed to nature’s elements. It only takes a tiny unprotected area to make wood vulnerable to insect and fungal attack.

protecting wood

Once wood dries out, insects, such as termites and wood borers, and other elements, such as fungi and the sun’s UV rays, start attacking the wood. Wood consists of wood fibres; the tighter these are and the denser the wood is, the harder it will be for the decomposition process to take place. However, slowly but surely, all bark is penetrated and the wood fibres break down, eventually becoming compost to continue the cycle of more nutrients being fed into the soil.

 

Protecting wood


When we make anything out of wood, we try to defy nature and protect the wood from this biological attack, not only to keep the wood beautiful, but also to protect the structure’s integrity.treating wood There are various methods used to treat timber, but the most popular, at least before hitting the shelves, is the vacuum pressure process. Here, the timber is placed in a cylinder that is then sealed, and a vacuum is drawn over the timber to remove the air in the wood fibre cells for a predetermined period before the cylinder is flooded with preservative while maintaining the vacuum. When the flooding is complete, the preservative pressure in the cylinder is raised and held until the required retention is attained.

treating wood

 

* Fungi: These are classified as a separate kingdom, with characteristics of both plants and animals, but different from plants in that they have no chlorophyll in their structure. Fungi feed on the compounds of the cell wall and consequently can weaken the structure of the wood to such an extent that the wood breaks and crumbles away. They develop from minute spores and, when geminated in suitable conditions, send out filaments called hyphae. These penetrate the wood structure and, if suitable conditions exist, break down the wood tissue into simple chemical compounds on which they feed. The development of such an attack can be rapid. Not all fungi weaken wood, but they can adversely affect the appearance.

* Wood borers: Almost any wood can be attacked by wood borers of one sort or another. Infestation by some wood borers may be of little or no significance, whereas attack by other borers may be serious and necessitate remedial action. Wood borers are beetles that, at the adult flight stage of their development, lay eggs into exposed wood, which serves as food for the larvae. Beetles pass through four distinct stages of development: Egg, larva, pupa and adult.

With the majority of wood borers, the major damage to wood material is done by larvae, which actively tunnel into the timber where they derive their nourishment. With limited exceptions, the only damage adult beetles cause is the cutting of a flight or emergence hole through the surface of the timber as they escape from it. After emergence they only live for a few weeks. After mating, the females may re-infest the timber from which they emerged. One species worth mentioning is the Hylotrupes bajulus, known in South Africa as the Italian beetle because it is believed that it was introduced into the country in timber packing cases that contained marble imported from Italy. They are known to only attack softwood species, such as pine, on mainly the coastal belt of South Africa. Lyctus brunneus is another commonly found wood borer, also known as the powderpost beetle, which only feeds on the sapwood of hardwood species.

* Termites: These are tiny insects that feed on wood. When the exterior of a home is not tightly secured and the foundation not properly treated against termite attack, these insects can work their way into the cavity walls to any wood, whether used as joinery, mouldings or structural supports. Termites will continue to eat at wood until it is totally destroyed. A termite problem can become so bad that the support beams and interior of your home can deteriorate and fall apart. Also known as white ant, their damage is accepted as a significant risk to the building and other structural timbers in most parts of South Africa. Get rid of termites as soon as you can. Wherever there is a risk of termite attack, it is wise to take some precautions.

For building, these precautions usually take the form of chemically treated soil barriers or physical barriers and the use of properly preserved timber treated with an approved and registered wood preservative in accordance with the relevant South African national standard.

 

Treatment


 

Very few timbers are naturally durable and hardwoods that are durable can be very expensive. Hardwood timbers, although more durable, can crack and split and still require some form of protection. The cheaper, locally grown timbers that can be used are pine or saligna. Fortunately, with proper impregnation of a suitable wood preservative, these timbers can offer long-term durability.treated wood There are various timber preservatives available. Some are not suitable for timber in contact with the ground, while others protect timber in all possible applications. Creosote and CCA preservatives are equally suitable for the support poles and bearers, and CCA-treated timber is suitable for the timber. CCA-treated timber has a greenish colour, while creosote colours timber dark brown or black.

treated wood

Timber treated with boron or tributyltin oxide (TBTO) does not change its natural appearance. These two preservatives are, however, leachable and should therefore contain a water repellent in the preservative in order to meet the H3 requirement of SABS 1288. This water repellence property has to be maintained to prevent leaching of the preservative.

A water repellent also protects the timber from degradation from weathering. In order to inhibit the effects of ultraviolet rays at the same time, an inhibitor may be added in the form of a brown or red colourant. Remember, the use of treated timber ensures that timber is protected against attack by termites, borers and fungal decay. wood treatmentShould it be necessary to paint the timber, boron, TBTO and CCA-treated timber can be painted directly.

wood treatment

Creosote timber can also be painted, provided it is first coated with a bituminous-based aluminium coating. As a general rule, preservative treated timber in its natural form is the easiest and cheapest solution. Remember that support poles should never be cut. Order them in the lengths required. Only beams, boards and bearers should be cut if necessary. However, their ends should be brushed with a preservative before assembly.

Sources
Timberlife – www.timberlife.co.za. South African Wood Preservers Association – www.sawpa.co.za.

 

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Comments

  1. Victor

    I want to varnish my timber weight bearing poles which are currently creosoted . They are exposed to harsh sun every day . The creosote after a while gets very powdery and messy . If a person brushes against the pole , all the creosote comes off on clothes or skin . I want to varnish over the creosote after sanding the poles . How should I go about it ?