Pine Sleeper H4

What does H4 treatment mean for timber and why does it matter?
H4 is a level of preservative treatment that provides the wood protection against termites, borers & fungal decay in projects that are in contact with or close to the ground. It's a higher treatment level than H3, which is only rated for above-ground use. For retaining walls, garden sleepers and fence plinths that sit in or near the soil, H4 is the correct specification.

What's the difference between H3 and H4 treated pine sleepers?
H3 treatment is suitable for above-ground locations where the timber is exposed to weather but not in contact with the ground. H4 treatment provides a higher level of protection specifically for in-ground and ground-contact use. If your project involves soil contact, always use H4 treated pine.

What can I use a treated pine sleeper for?
You can use these sleepers for a wide range of outdoor timber projects like retaining walls, raised garden beds, garden edging, stepping stones and fence plinths. They're not appropriate for structural building applications like bearers, joists or for supporting loads.

Can I use treated sleepers for a vegetable garden or edible garden bed?
This is a common question and worth considering carefully. CCA treated timber contains copper, chrome and arsenate. There is some debate about whether these compounds can leach into soil in quantities that affect edible plants. If you'd prefer to stay away from CCA, then our Hardwood Sleepers are H4 treated with AQC - which doesn't contain any arsenate. For vegetable gardens and edible garden beds, lining the inside of the sleeper frame with heavy-duty plastic sheeting before filling with soil is a widely used precaution that minimises any direct contact between the treated timber and the plants you're growing.

How long will H4 treated pine sleepers last in the ground?
This depends on the soil conditions, drainage and the specific project. You can generally expect treated pine sleepers to last 15-25 years or more. Well-drained sites with good airflow tend to extend the life of the timber, whereas constantly wet or waterlogged conditions will significantly shorten it.

What is a fence plinth and why do I need one?
Using a treated pine sleeper as a fence plinth is the most practical way of extending the life of a fence. Every well-built fence will have a plinth underneath it. They sit at ground level between fence posts and keep the bottom of the palings off the ground and away from damage caused by garden tools. Learn more about fence plinths.

How do I join pine sleepers together for a retaining wall?
To join two sleepers along a horixontal line, use our Galvanised H Posts. When creating a 90 degree angle between two sleeepers, use a Galvanised Corner Post. Then, use a Galvanised C Post to frame the final sleeper on an end. These framing posts hold the end of the sleepers together. You'll need to finish the back side of the posts with retaining wall wedges to keep the sleepers facing the front flush.

Can I paint or stain pine sleepers?
Yes, though many people leave treated pine sleepers in their natural state for landscaping projects. If you want to change the colour or match a specific finish, a quality exterior timber stain like QCoat works well on pine. Avoid film-forming paints on surfaces that will be in ground contact as they can trap moisture and accelerate decay at the edges.

Are Pine Sleeper H4 suitable for structural use?
No, they are not appropriate for structural building applications such as bearers, joists or any load-bearing element in a building structure. For structural applications our pine framing is the best option but is only H3 treated and cannot be in-ground.