Kwila / Merbau External Stair String (pair)

40mm Open House External Stair String – Kwila / Merbau (pair)

Elevate your external staircase with our precision-machined 40mm thick Kwila / Merbau open house string, specifically selected for outdoor use thanks to its excellent natural durability and resistance to the elements. For custom floor finishes or non-standard requirements, see our stair configurator to order custom strings. These strings are sold as a pair and delivered as a left hand and right hand string together.

Dimensions & Profile:

• Thickness: 40mm
• Going: 240mm or 250mm
• Rise options: 170mm, 175mm, 180mm, 185mm or 190mm
• Upper and lower finishes set to 12mm – can be packed up or cut down on site to suit finished floor levels
• Precision-machined pockets designed so our Kwill 40mm external treads simply slip into place

This string is made specifically for open house external stairs, where the treads are housed into the string without the need for wedges. It works equally well as a wall string or outer string and pairs perfectly with our 40mm Open Timber Stair Treads for a clean, secure outdoor fit.

Kwila / Merbau is a dense, stable hardwood with high above-ground durability and natural resistance to termites and decay, making it well suited to Queensland’s external conditions. Perfect for both new builds and renovations, the 40mm construction delivers reliable long-term performance on external stairs while providing a neat, continuous side profile.

Key Benefits:

• Easy assembly with accurately cut pockets for a straightforward slip-in tread fit
• Smooth, sanded surfaces ready for oiling or sealing for external protection

All products are delivered raw, pre-finished sanded to 100 grit.

Kwila (also called Merbau) is a tough Australian and Southeast Asian hardwood that brings rich, warm colour to stair work. Freshly cut it shows golden to orange-brown tones that deepen over time into a handsome reddish-brown, often with small yellow flecks scattered through the timber. The grain is usually straight to interlocked with a moderately coarse but even texture, giving a clean, solid look once finished. Dense, hard and highly durable, Kwila stands up well in high-traffic areas and is a reliable choice for treads, risers, stringers, handrails and balustrades. It’s the go to choice for affordable external timbers as it naturally deters termites and is less susceptible to water ingress.