Cumarú Prime KD smooth decking board 21 × 90 mm – fixed lengths

The Cumarú Prime KD smooth deck board 21 × 90 mm is a particularly high-quality and long-lasting decking material for outdoor areas. With its natural red/brown tone, high hardness, and durability class 1, it stands out due to its elegant appearance, high stability, and excellent weather resistance.

Product description

The Cumarú Prime KD deck board is one of the premium hardwoods for durable deck constructions. The wood originates from northern South America and gives decks, balconies, and outdoor areas an elegant, natural appearance with its warm red/brown tone.

Particularly noteworthy is its very high natural durability: according to DIN EN 350-2, Cumarú corresponds to durability class 1, making it exceptionally well-suited for long-term outdoor use – even without special protective measures.

With a bulk density of approx. 1000–1200 kg/m³ (at 12–15 % wood moisture) and a Brinell hardness of 45–58 N/mm², Cumarú is significantly harder than many domestic wood species, such as white oak. This makes the board resilient and durable.

The KD (kiln-dried) specification describes technical drying to 16–18 % wood moisture under controlled conditions. Since Cumarú shows increased swelling and shrinkage behavior (during slow moisture absorption/release), a gap of 4 mm (at 16–18 % wood moisture) must be planned for during installation.

Due to the high hardness of the wood, carbide-tipped tools should be used for processing. Pre-drilling is mandatory for fastening to avoid screw breakage and cracking.

✅ Advantages at a glance

• Cumarú Prime KD deck board – very durable and stable

• Natural red/brown tone for an elegant deck look

• Durability class 1 according to DIN EN 350-2

• Very high Brinell hardness (45–58 N/mm²) – especially resistant

• Kiln-dried (KD) to 16–18 % wood moisture

• Slow moisture absorption/release for controlled behavior

• Ideal for high-quality outdoor areas and long-term use

Processing & installation notes

• Gap spacing: approx. 4 mm at 16–18 % wood moisture

• Tools: Use of carbide tools recommended

• Fastening: Pre-drilling required to avoid cracks and screw breakage

• Account for swelling and shrinkage behavior during planning

Technical data

• Wood type: Cumarú Prime

• Finish: KD smooth

• Dimensions: 21 × 90 mm

• Lengths: Fixed lengths

• Color: natural red/brown tone

• Wood moisture (KD): 16–18 %

• Durability: Class 1 (DIN EN 350-2)

• Bulk density: approx. 1000–1200 kg/m³ (at 12–15 % wood moisture)

• Brinell hardness: 45–58 N/mm²

Conclusion

The Cumarú Prime KD smooth deck board 21 × 90 mm is a great choice for anyone looking for a resilient, long-lasting, and visually elegant deck covering. Its exceptional hardness, natural durability, and warm coloring make it a premium wood for demanding outdoor projects.