Cumaru, also known as Brazilian Teak, is a premium tropical hardwood sourced from Amazon Basin, northern South America (Brazil, Venezuela, Guyana). With a Janka hardness rating of 3,330 lbf and a density of 65 lbs/ft³, Cumaru is classified as Class 1 - Very Durable — one of the most durable commercial lumber species available. The heartwood exhibits light to medium brown with reddish tones with interlocked grain, medium to coarse texture, creating a striking natural appearance that improves with age.
Why Choose 5/4x4 Cumaru Wood for Your Deck?
Cumaru decking delivers a naturally slip-resistant, splinter-free surface that stays cool underfoot even in direct sunlight. Unlike composite or pressure-treated alternatives, it never fades to a dull gray unless you want the natural silver patina look. Properly installed 5/4x4 Cumaru decking delivers a service life of 50+ years with minimal maintenance — an optional annual oil treatment preserves the original color, or you can let the Cumaru wood weather to a distinguished silver-gray patina. Cumaru carries a Class A - Low flame spread, making it suitable for wildfire-prone regions where code-compliant materials are required.
The 5/4x4 pregrooved profile has factory-milled grooves along both edges, designed specifically for hidden fastener clip systems like Ipe Clip or DeckWise. This creates a clean, screw-free surface with no visible hardware. All Cumaru lumber is available in Select and Better grade with lengths ranging from 4′ to 20′. For detailed step-by-step instructions, consult our Cumaru installation guide. Long-term care recommendations are covered in our Cumaru maintenance guide.
5/4x4 Cumaru Decking — Installation & Coverage Specs
- Recommended joist spacing: 16"–24" on center for 5/4x4 boards (1" actual thickness)
- Fastener placement: Hidden clip fastener in each factory-milled groove, one clip per joist
- Board weight: A 12-foot 5/4x4 Cumaru board weighs approximately 20 lbs (1.65 lbs/LF)
- Coverage: Each 12-foot 5/4x4 board covers 3.5 sq ft of decking surface (3.5" face width)
- Pre-drilling required: Always pre-drill in Cumaru — the 3,330 lbf hardness prevents direct screwing
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