What is H4 Treated Pine?

H4 treated pine timber

H4 Treated Pine timber is structural lumber that was introduced to the building industry in 1970. It is also known as PT (Pressure Treated timber products) and is treated with chemicals for greater insect and weather protection than untreated pine.

Today, treated pine timber accounts for about half of all lumber used on residential construction sites because it offers improved value over other building materials. It has become our nation’s most popular exterior wood for its strength, ease of use, lower cost and rot resistance.

Where is H4 Treated Pine Timber Used?

In Australia, H4 treated pine timber is used for a wide range of structures and external applications, including:

What are the Benefits of Using H4 Treated Pine?

H4 treated pine provides many great benefits such as:


It has exceptional strength, only able to be surpassed by steel.


May last indefinitely if maintained properly.


Unlike other building materials, treated pine timber is long-lasting with little maintenance required throughout its lifetime.

Ease of use

Very easy to work with when building or renovating.


Very cost-effective and affordable.

How is H4 Treated Pine Treated?

H4 Treated timber for use in exterior applications, whether it be decks or pergolas, is pressure-treated with a water-based preservative called chromate copper arsenate (CCA). When the treated timber dries out it may form a solid, crystalline structure that may not make the wood rot or warp. H4 treated pine is also known as ‘waterproof’.

What Kind of Toxins are Involved in Treating H4 Pine?

Treated pine contains ingredients that have been approved by the Australian Government for general usage on building projects. The primary chemicals used are algaecide, rust inhibitors, fungicide and preservatives of copper chrome arsenate. These chemicals are contained within an organic chemical compound called Chromated Copper Arsenate (CCA) which is impregnated into the wood cells while the timber treated process is happening, to provide protection against insects and fungus.

What Type of CCA Chemicals are Used in H4 Pine Treatment?

The active ingredients of the chemical solution are one percent methyl bromide, two percent ammonium diuranate, 0.2 percent sodium borate, 2.5 to 4.0 percent copper oxide and 5.0 to 7.5 percent chromium oxide, with small amounts of arsenic, cadmium and lead.

What is the Safety Information of H4 Treated Pine?

There are a number of studies that have been undertaken in Australia and overseas over the past 30 years that support both the Australian Standard AS/NZS 2216:1998, ‘Specifications for preservative treatment of structural timber’ and the chemical compound used with the timber treatment process. The most recent study was completed in 2006 and is called ‘Assessment of Copper Chromium Arsenate (CCA) treated timber products for use in Western Australia.

Preservative Treated Timber

is a good choice for new construction projects requiring weather-resistant exterior lumber because the treatments provide a high degree of protection against termites and decay. The treated wood is also strong, stiff and can span many times its strength in-service loads.

In today’s market, the most common treatment process for PT Pine timber is Chromated Copper Arsenate (CCA), which provides excellent protection from all types of insects as well as from fungal decay. These preservatives are highly effective on both ends of the spectrum, hot/wet or cold/dry climates so this type of pressure.

H4 treated pine timber
Use of Treated Pine Timber

Common Preservatives Used to Treat Pine

timbers are known as CCA (Chromated Copper Arsenate), ACZA (Alkaline Copper Zirconium), CA (Copper Azole) and CD (copper-based). These chemical preservatives make it possible to lengthen the service life of the wood by years, or even decades. LOSP (Light Organic Solvent Preservative) is also commonly used.

These chemicals can leach out of treated timber into soil, water or air that surrounds them. At present, there is no set safety standard for residual chemicals in treated wood products. As these chemicals are transported away from the initial treatment area the levels decrease over time, nevertheless, many people wonder what can be done about old boards that may contain high levels of chemicals?

What to Do with Treated Pine Timber in Older Homes?

Although the wood is very strong, it does not need to be replaced. It can be cleaned up on site by first removing all old coatings with a power washer or sandblaster. Carefully brush any loose material from corners, edges and ends of boards before power washing or using a belt sander. After cleaning, if you are concerned about potential leaching vacuum the dust left behind with HEPA filters, do not sweep.

Give treated pine time to dry out thoroughly after removal so it may burn well in your fireplace this winter.

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