LOSP timber

What Is LOSP Timber?

LOSP stands for Light Organic Solvent Preservative — a treatment that protects timber against fungal decay, rot, and insect attack. It’s often used as an alternative to water-based treatments like CCA or ACQ, especially when the job calls for timber that needs to stay dry and true.

Since LOSP doesn’t increase the timber’s moisture content, there’s less movement after treatment. That means straighter boards, better paint adhesion, and no hold-ups waiting for timber to dry before finishing. It’s a solid choice for work where a clean, stable finish is important.

Where is LOSP Treated Timber Commonly Used

You’ll find LOSP timber used in a range of outdoor applications, especially where the timber is both structural and visible:

• Pergolas and verandah frames
• Beams and fascia in alfresco areas
• External wall framing for sheds or garden rooms
• Landscape features like posts and screening
• Decorative battens and trims in entryways or fences

It performs well in above-ground, weather-facing builds where moisture and insect exposure are a concern.

Why Builders Use LOSP Timber Posts

• Dry after treatment — no swelling, no extra wait time
• Holds its shape better than many wet-treated alternatives
• Paints up well, especially when pre-primed
• Easier on fixings — less risk of fastener corrosion
• Lightweight and simple to cut, drill, or install
• Meets Australian H3 standards for above-ground external use

At Greenhill Timbers, we supply timber that helps you get the job done properly the first time and makes your builds easier to maintain long-term.

LOSP Treated Timber Sizes in Stock

We stock a range of dressed LOSP timber sizes suited to structural and decorative use:

• 42 × 42
• 66 × 42
• 90 × 42
• 138 × 30
• 112 × 112
• 185 × 185

All our LOSP timber pieces are Dressed All Round (DAR), giving you a smooth, paint-ready finish.

Before You Build – What to Know

A few practical tips will help you get the most out of your LOSP timber:

• Let it air if freshly delivered — some vapour from the solvent may linger
• Always seal cuts and drilled holes with an end-grain preservative
• Apply your topcoat soon after installation to lock in long-term protection
• Only use it for above-ground work — it’s not designed for in-ground contact

These steps help preserve the treatment and extend the life of the timber in exposed conditions.

Why Get LOSP Timber from Greenhill Timbers Melbourne?

We’re not just another timber yard. Here’s why our customers keep coming back:

• Reliable stock – We keep common sizes on hand so you’re not left waiting
• Quality control – Every length is checked for straightness and finish
• Trade-friendly service – Quick turnaround, forklift loading, and bulk rates
• DIY support – Friendly advice if you're not sure what to use or how much
• Custom orders welcome – We’ll help you plan out your cut list and supply what you need

From big framing jobs to backyard builds, we’ve got the timber and the team to back you.

Need Help Choosing the Right Size or Profile?

If you're not sure which section suits your job, just ask. Whether you're framing out a pergola or adding vertical battens to an outdoor wall, we'll help you find the right LOSP timber and give you the practical advice to go with it.

Call or visit Greenhill Timbers' warehouse in Melbourne, and we’ll make it easy to get what you need.