What is H4 treated pine?

H4-rated treated pine protects against severe decay as well as termites.

H4 treated pine is a type of wood that is not only durable and cost-effective, but can be used in many different applications.

But what exactly is H4 treated pine?

This blog post covers everything you need to know.

What is H4 treated pine?

H4 treated pine is a type of timber that’s been chemically treated to withstand decay under severe weather conditions.

It’s moisture-resistant and also protected against insects, including termites.

Because H4 is suitable for outside, in-ground use, it can be used for fence posts, decking foundations, or other applications where the wood will contact the soil.

What is H4 pine used for?

H4-rated treated pine is suitable for a wide variety of outdoor applications, including:

  • Decks and pergolas
  • Fence posts
  • Garden edging
  • Timber framing
  • Pergola posts
  • Landscaping and retaining walls

What is the difference between H2 and H4 treated pine?

H2 treated pine is used for indoor projects and cannot get wet, whereas H4 treated pine can be used for outdoor projects, either above or in-ground.

H2 treated pine is less expensive than H4 but doesn’t offer as much protection against the elements. It protects against insects, including termites, but not against fungal decay (rot).

H4 treated pine protects against fungal decay because it’s designed to be installed outdoors or in direct contact with soil (like a retaining wall), where damp conditions are more likely.

What is the difference between H3 and H4 treated pine?

H3 Treated Pine is treated against termites, borers and fungal decay. It is suitable for outside, above-ground use only.

H4 Treated Pine provides additional protection to H3, protecting against severe decay that can occur when timber is in contact with water, such as for your decking posts that are in contact with the ground.

How long does H4 treated pine last in the ground?

The lifespan of H4-treated lumber is typically longer than 30 years, but it depends on the type of timber and the conditions it’s exposed to.

The most common factor that affects the longevity of pressure treated wood is moisture. The more exposure to wet soil it gets, the shorter its life span will be. Protecting your posts from excess moisture can help them last longer.

Of course, if you use lumber with severe defects like cracks, then no matter what treatment method you choose there’s very little chance that piece will hold up for very long.

Can you use H4 treated pine for garden beds?

H4 treated pine is suitable for garden beds where the soil may be damp.

This is because it’s designed to resist rot and termites when buried in the ground – as well as above ground.

CSIRO has said that the risk from using CCA treated timber for vegetable gardens is within tolerable limits.

However, for growing root vegetables, some people prefer to not use any kind of treated timber.

Some people who used treated timber for vegetable gardens like to line it with plastic or paint the timber with an exterior grade paint.

If you’re building a garden for growing vegetables, the safest option is to use untreated hardwood sleepers like Kwila (Merbau) or Jarrah.

You could also consider using the newer ACQ-treated pine sleepers (which are arsenic-free).

Does Bunnings sell H4 treated pine?

Bunnings stocks a range of H4 treated pine.

Sizes include:

  • 200 x 50mm 1.2m
  • 200 x 50mm 1.8m
  • 200 x 50mm 2.4m
  • 200 x 50mm 3.0m
  • 200 x 50mm 3.6m

At the time of writing, prices for Bunnings H$ treated pine range from $9.40 to $28.40


What sizes does H4 treated pine come in?

H4 treated pine timber comes in a range of sizes and is available from many building supplies and DIY stores including Bunnings, Mitre 10, and more. Many different lengths are typically stocked by suppliers but common sizes are 2.4m, 2.7m, 3.0m, and 3.6m. Most suppliers will also be able to offer custom cut lengths if you need a specific size or want to avoid waste from buying a full-length length and cutting it down yourself.