Structural timber can be treated for protection against termites and is said to give at least a 25-year guarantee against attacks. Other treated timber products range from particle board flooring, decay and termite resistant window reveals, fascia board, decking, hand rails, sleepers and engineered wood products such as LVL or Glulam beams.
Treated timber against termites varies in hazard levels from H2 to H6, with H6 being the highest. H2 treated timber is for internal above ground timber (house framing, skirting boards, architraves, flooring); H3 for external above ground (patios, pergolas); H4 and H5 for external in ground (fence posts, vegetable garden edging, house stumps); and H6 for marine environments. Within the H2 level, there is also the sub-classification of H2-F for tropic areas in Australia.
According to the Timber Preservers’ Association of Australia (TPAA), the three types of treatment include vacuum/pressure impregnation, which is used for deep protection for piles, poles, fencing, building timbers and many types of wood used in domestic and industrial construction; double vacuum/immersion, used for building timbers not in ground contact, such as cladding, decking and fabricated joinery components; and dip/spray, designed to protect timber against insect attack for indoor or sheltered situations above ground.
The TPAA says there are three main types of preservatives used. These include water-borne preservatives, which can be applied to timber indoors and outdoors; oil-borne preservatives, used on timber primarily for heavy duty construction and in the marine environment; and light organic solvent preservatives (LOSP), which can be used on timber with high value joinery and similar products and can only be used for out of ground contact.
AKD Softwoods uses Tanalith T (‘Termiblue’), which is an oil based preservative that contains a synthetic pyrethroid (permethrin) as the insecticide. Its product achieves a 5 mm envelope, which ensures the chemical gets into the timber and any work done on-site will not compromise the product’s effectiveness. “The Termiblue Radiata Pine is kiln dried and then impregnated using a treatment vessel that can be used to either produce H2, H2-F or H3 treated timber,” says John Hayden, chief executive officer at AKD Softwoods.
The company uses the LOSP method for its Termiblue product to produce a dry and dimensionally stable product that is available for application immediately after completion of the process. Its treated timber can be used for dry internal structural and non-structural framing, such as wall frames, roof trusses, rafters, battens flooring and mouldings.
Hyne has three treated timber products. T2 Blue was developed specifically for areas south of the Tropic of Capricorn and has an H2-F level treatment which complies with AS 1604. Hyne’s T2 Red, on the other hand, has been designed for areas in tropical Queensland. T3 Green comprises both termite and fungal protection for above ground outdoor use. All products come with a 25-year guarantee. In its Trueframes range, Hyne provides an environmentally friendly alternative to other chemical treatments available on the market in a variety of strengths.
“Hyne T2 Blue undertakes a 5 mm envelope treatment in a formulation that provides total protection, while containing minimal volatile organic compound (VOC) emissions. Hyne T2 Red is made to be resistant to the more voracious species found in Central and North Queensland, so the timber undergoes pressure treatment with the solution,” says David Marley, general manager marketing at Hyne.
Like most structural timber used in the construction of Australian homes, plantation pine is most commonly used for treated timber. Hyne uses the same structural MGP-graded plantation softwood as it uses in non-treated products, with its timber sourced from sustainably managed plantations.
Boral provides two treated timber products — Pinegard Blue (H2-F) and Pinegard Red (H2) termite resistant structural timbers and flooring. Pinegard Blue is a linseed-based 5 mm envelope treatment and is suitable for termite resistant structural uses south of the Tropic of Capricorn. It is available in sizes from 70 mm x 35 mm, up to 240 mm x 45 mm, and particle board flooring. Pinegard Red is suitable in all tropics of Australia and is available in sizes starting at 70 mm x 35 mm and upwards. Both products come with a 25-year guarantee.
“Boral Pinegard Red and Pinegard Blue termite resistant structural timber and flooring products use permethrin; a synthetic pyrethroid to impart termite resistance. Permethrin acts in two ways, firstly as a repellant and secondly as a poison to termites. Permethrin has a low toxicity to mammals and does not represent any major environmental dangers,” says Peter Stagg, national sales manager at Boral.
Boral manufactures its treated timber from plantation grown softwoods, including Radiata Pine, Hoop Pine, Carribea Pine and Slash Pine. “In general it is not the type of timber being used that determines the treatment required, rather it is the end application or hazard level that determines the treatment required,” Stagg says.
“The different levels of timber preservative required to achieve a H2 or H2-F level vary according to the density of the species being treated, with the greater the density the more preservative that is required to achieve the desired level of termite protection. Different types of timber generally do not require different treatments. For example, the timber used to construct a Glulam beam is treated to the same standard as a structural pine stud using the same chemical.”
Marley says the cost of building with treated timber and non-treated timber is “minimal” when you take into account the house is protected for at least 25 years from termite attack. According to the Plantation Pine Framing Campaign, the cost of using treated timber is less than 1 per cent of the value of the average house. Marley says, “To achieve protection for the next 25 years you only need to outlay the cost of perhaps a new plasma TV or BBQ.”