The current solid Merbau post range includes 75×75mm, 90×90mm, 100×100mm, 120×120mm, 150×150mm and 200×200mm sections. Posts are available in various lengths depending on the size and current stock.

Merbau is a dense hardwood commonly selected for decks, pergolas, privacy screens, balustrades, outdoor structures and architectural applications.

Check the individual product specification for the size you are buying, as this varies across the range. The 90×90mm and 100×100mm solid Merbau posts are described as kiln dried and dressed all round (DAR). A DAR finish provides a dressed, consistent surface suitable for installation, finishing or further machining.

Yes. Solid Merbau posts are used across a range of outdoor applications including deck structures, pergolas, privacy screens, balustrades, garden structures and architectural features. The correct post section and connection system depend on the specific structural application.

This is the most common point of confusion. Our U-Cup post supports are named post size × shaft length.

So a U-Cup Post Support 90×300mm is sized for a 90mm post and has a 300mm shaft — it is not a support for a 90×300mm timber. The first number must match your post; the second number is how far the support extends below the cup, which you choose according to how it is being fixed or set.

The bolt-down anchors follow a different convention — for example 90mm × 4mm × 110mm is post size × plate thickness × height.

Use this as a starting point, then confirm the actual internal cup dimensions and fixing method against the individual product page before ordering.

• 75×75mm post — U-Cup Post Support 75×75mm; U-Cup Stirrup 75×150, 75×200, 75×300, 75×450 and 75×600mm; 70mm×4mm×115mm M12 bolt-down U-Cup stirrup
• 90×90mm post — U-Cup Post Support 90×75, 90×130, 90×150, 90×200, 90×250, 90×300, 90×450 and 90×600mm; 90mm×4mm×110mm M12 bolt-down U-Cup; 90mm "Thin Style" adjustable bolt-down stirrup; Bolt-On T-Blade Heavy Duty 90×250mm
• 100×100mm post — U-Cup Post Support 100×75, 100×130, 100×150, 100×200, 100×250, 100×300, 100×450 and 100×600mm; 100mm×4mm×105mm M12 bolt-down U-Cup; 100mm "Thin Style" adjustable bolt-down stirrup; U-Cup Post Support 100 No Shaft
• 120×120mm post — no exact 120mm support is stocked. Nearest options: U-Cup Post Support 125×75mm, U-Cup Post Support 115×450mm, 115mm×4mm×105mm M12 bolt-down U-Cup, Bolt-On T-Blade Heavy Duty 115/125×250mm. Contact us to confirm fit before ordering.
• 150×150mm post — U-Cup Post Support 150×75mm; 140mm×8mm×180mm M12 bolt-down U-Cup in galvanised or 316 stainless
• 200×200mm post — no standard support is stocked at this size. Posts of this section are typically part of an engineered connection — contact us to discuss the application.

No. A support should be selected according to the actual post dimensions, support configuration and connection requirements. A 90×90mm post should not be placed into a support intended for a substantially different post size — an oversized cup allows movement, and an undersized one will not seat correctly. The connection also needs to suit the substrate and the loads imposed on the post.

The shaft length depends on how the support is being installed. Shorter shafts (75–130mm) are generally used where the support is bolted down onto an existing concrete slab or structure. Longer shafts (300–600mm) are typically used where the support is set into a concrete footing, with the shaft providing embedment depth. The required embedment for your footing depends on the structure, loads and site conditions.

A post support or stirrup separates the timber from direct contact with the ground or supporting substrate, reducing exposure to persistent moisture. This matters for outdoor timber structures because good drainage and detailing contribute significantly to long-term durability.

The choice depends on the environment and fixing conditions. Our hardware range includes both hot-dip galvanised and 316 marine-grade stainless-steel supports. In coastal, marine or particularly aggressive environments, stainless steel may be preferable. Merbau is a dense hardwood containing tannins, so compatible corrosion-resistant hardware is important for exposed applications.

Because Merbau is a dense hardwood, pre-drilling can be advisable, particularly when fixing close to ends and edges, to reduce the risk of splitting and make installation easier. The appropriate drill size and fixing method should follow the hardware manufacturer's requirements.

Yes. Several of the bolt-down supports in our hardware range are designed for fixing to concrete bases or existing timber decking, while stirrup designs can also be set into concrete. The specific anchor, bolt size, embedment, substrate and edge distances need to be suitable for the application.

No — post size is only one part of the structural design. The required section depends on factors including post height, tributary load, span, roof loads, wind exposure, connection details, footing design and the intended use of the structure. A larger post is not automatically a substitute for engineering the complete structure.

Start with the required post section and structural application, then select a compatible support based on the actual post dimensions and fixing method. For load-bearing structures such as elevated decks, pergolas, carports and roofed structures, the post, support, footing and connections should be selected as part of the overall structural design rather than independently.

Post supports are not a structural substitute for correct post sizing or engineering. Where the post is load-bearing, confirm the design with a suitably qualified building professional or structural engineer.

Browse the full Decking Wood QLD range of Merbau posts, post supports, decking timber and hardware.