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A versatile Balau hardwood decking board with a ribbed face and smooth reverse — giving you two finish options in a single board. Install ribbed face up for improved grip and anti-slip performance in wet conditions, or smooth face up where a cleaner, more refined appearance is the priority. The same premium Yellow Balau tropical hardwood as the rest of our Bangkirai decking range, at the widely used 21x145mm size.
At 21mm thick and 145mm wide, these ribbed hardwood decking boards suit residential gardens, terraces, patios, and commercial outdoor spaces equally well. The 145mm face width covers ground quickly with fewer board runs per square metre, while the ribbed profile channels surface water away underfoot — making this board a practical all-rounder for UK outdoor conditions.
| Specification | Detail |
|---|---|
| Species | Yellow Balau (Bangkirai / Shorea laevifolia) |
| Timber type | Tropical hardwood |
| Profile | Ribbed face / smooth reverse — reversible |
| Dimensions | 21 x 145 mm |
| Fixing method | Face fix |
| Durability class | Class 1–2 (very durable) |
| Density | Approx. 980 kg/m³ |
| Janka hardness | Approx. 1,600 lbf (7,120 N) |
| Natural lifespan | 25+ years above ground |
| Origin | Southeast Asia (Malaysia / Indonesia) |
| Max joist spacing | 400 mm centres (residential) |
| Supply | UK nationwide |
The ribbed face of this board is machined with a grooved profile that channels water away from the surface underfoot. This improves grip in wet conditions and makes the board suitable for areas that see regular rain exposure — garden decking, terraces, steps, and any surface where a degree of anti-slip performance is desirable without specifying a fully textured board on both faces.
The smooth reverse gives you the option of a flat, refined finish if your project calls for it — install smooth face up and the board reads as a clean, contemporary hardwood deck surface. This reversibility makes the ribbed 21x145mm board the most flexible option in our Balau range, adapting to both practical and aesthetic priorities on the same product.
We stock three Yellow Balau decking boards to suit different project requirements:
| Board | Profile | Size | Best for |
|---|---|---|---|
| Smooth 21x145mm | Smooth both faces | 21 x 145 mm | Contemporary, minimal finish |
| Ribbed 21x145mm (this board) | Ribbed face / smooth reverse | 21 x 145 mm | Versatile — grip or clean finish |
| Dual Ribbed 25x145mm | Ribbed both faces, two patterns | 25 x 145 mm | Maximum grip — poolside, steps, commercial |
Yellow Balau and Bangkirai are the same species — Shorea laevifolia, a dense tropical hardwood native to Southeast Asia. Yellow Balau is the UK and Malaysian trade name; Bangkirai is the Indonesian and Dutch equivalent. Both are among the most popular hardwood decking timbers sold in the UK, valued for their combination of natural durability, hardness, and warm golden-brown appearance.
With a density of approximately 980 kg/m³ and a Janka hardness of around 1,600 lbf, Yellow Balau is one of the hardest decking timbers available in the UK market. Its natural oil content — comparable to teak — gives it inherent resistance to rot, fungal decay, and wood-boring insects without chemical treatment, achieving a natural durability class of 1–2 and an expected service life of 25 years or more in above-ground outdoor conditions.
These Balau decking boards are face fixed. Pre-drilling pilot holes before driving screws is essential — Yellow Balau is extremely dense and will split boards or shear screws without pilot holes. Use stainless steel A2 or A4 screws throughout; the natural tannins in Bangkirai react with lower-grade metals and cause surface staining. Leave a 5–6 mm gap between boards for drainage and seasonal movement, and acclimate boards on site for 48–72 hours before installation.
Install on a level, well-ventilated subframe with joists at maximum 400mm centres for residential use, reducing to 300mm for commercial or high-traffic applications. Seal all cut ends immediately after cutting with a hardwood end-grain sealer or decking oil. We stock stainless steel screws and hardwood decking oils suitable for Yellow Balau and Bangkirai decking.
Yellow Balau does not require treatment to maintain its structural performance outdoors. Left untreated the boards will weather from golden-brown to silver-grey over approximately 12–18 months. To retain the warm original colour, apply a UV-stable penetrating hardwood decking oil before installation and reapply annually. Keep the ribbed channels clear of leaf debris and organic matter which can retain moisture over winter. Clean with a stiff brush and warm water — avoid pressure washing. We stock Remmers and Koopmans hardwood decking oils and stains suitable for tropical hardwoods including Yellow Balau.
Ribbed decking has a grooved profile machined into the board face. The ribs channel water away from the surface and provide texture underfoot, improving grip in wet conditions. This board has a ribbed face and a smooth reverse — install either face up depending on your finish preference.
The ribbed 21x145mm board has a ribbed profile on one face and a smooth face on the reverse. The dual ribbed 25x145mm board is ribbed on both faces with two different rib patterns. Choose the ribbed board for versatility; choose the dual ribbed board where maximum anti-slip performance on both faces is required.
Yellow Balau and Bangkirai are the same tropical hardwood species — Shorea laevifolia from Southeast Asia. One of the most popular hardwood decking timbers in the UK, with a natural durability class of 1–2 and an expected service life of 25 years or more outdoors without chemical treatment.
Face fix with stainless steel A2 or A4 screws. Pre-drilling pilot holes is essential — Yellow Balau is extremely dense and will split or shear screws without pilot holes. Leave a 5–6 mm gap between boards and acclimate on site for 48–72 hours before installation.
No treatment is required to maintain structural performance. Left untreated the boards weather to silver-grey naturally. To retain the warm golden-brown colour, apply a UV-stable hardwood decking oil before installation and reapply annually.
Add these boards to your basket above. For a full hardwood decking quote including boards, fixings, and woodcare — contact our team.
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