Cumaru 5/4×6 Decking Board (Grooved Both Sides)

Description

Engineered for Maximum Strength and Hidden-Fastener Performance

The Cumaru 5/4×6 Decking Board (Grooved Both Sides) (actual 1″ × 5½″) is built for projects that demand superior rigidity, structural confidence, and long-term durability. Each board features dual precision-milled grooves, enabling secure engagement with hidden clip systems for a completely clean, uninterrupted deck surface. This thicker 5/4 profile is preferred in applications where load requirements, traffic levels, or environmental exposure exceed the limits of standard residential builds.

Made from Premium Grade A, kiln-dried Cumaru—one of the world’s hardest and most stable hardwoods—this profile delivers exceptional resistance to rot, insects, abrasion, and moisture. Whether installed in commercial walkways, waterfront decks, rooftop terraces, or heavy-use backyard spaces, Cumaru’s natural density provides unmatched reliability.

When to Choose the 5/4×6 Grooved Profile

While 1×6 Cumaru remains the best all-around option for typical residential decks, the 5/4×6 format offers increased stiffness, improved live-load performance, and enhanced longevity. Builders select this heavier board when:

• Joist spacing exceeds standard residential spans
• Decks need greater impact resistance or structural redundancy
• Hidden-fastener systems are desired across the entire field
• Designs involve elevated platforms, docks, or municipal installations

The dual-groove design allows fasteners to lock on both edges, maintaining perfect spacing, precise alignment, and a uniform finished surface throughout long field runs.

Premium Material for High-End Outdoor Builds

Every board is crafted from hand-selected Cumaru hardwood, kiln-dried for stability and graded for consistent grain quality. Cumaru’s natural density and interlocking grain help reduce movement and maintain a flat, stable deck surface even in humid or coastal climates. With proper design and maintenance, Cumaru performs reliably in service lives of 30–50+ years.

Installation Support & Hidden Fastener Compatibility

This profile integrates cleanly with hidden fastener systems featured in our
BWD Clip Certified Installation Guide
and the
Deck Master Undermount System.
These guides provide spacing diagrams, movement allowances, and fastening best practices to ensure long-term performance.

For a deeper comparison of fastener styles—including surface screw, plug, and undermount systems—review our
Deck Fastening Methods Video.

Moisture Management & Long-Term Deck Stability

Proper airflow and drainage beneath hardwood decking are essential for preventing cupping or seasonal movement. Before finalizing your design, consult:
Hardwood Decking: Drainage & Cupping Guide.
This resource outlines proven strategies for airflow, spacing, and water management to protect your Cumaru deck for decades.

Sustainably Harvested, Responsibly Sourced Hardwood

Brazilian Wood Depot sources Cumaru exclusively from verified, sustainably managed forests. For a deeper look at international forestry standards, selective harvesting, and how hardwood sourcing supports long-term conservation, explore the
Sustainable Hardwood Certified Course.

See Real Cumaru Projects & Plan Your Build

Browse real-world Cumaru installations in our
Hardwood Decking Photo Gallery.
Use the
Decking Wizard
to generate layout ideas, fastener recommendations, and joist-spacing guidance tailored to your project.

Cumaru 5/4×6 Grooved Both Sides offers the perfect balance of overbuilt strength, hidden-fastener clean design, and long-term hardwood performance. It’s the professional’s choice for premium outdoor construction.