5/4x6 Cumaru Wood Decking board profile diagram
Decking

5/4x6 Cumaru Wood Decking

This 5/4x6 Cumaru Wood decking board pairs the proven outdoor performance of Cumaru (Brazilian Teak) with a 3,540 Janka hardness rating — one of the hardest commercially available woods on earth. This Class B fire-rated hardwood withstands extreme weather, UV exposure, and heavy foot traffic without chemical treatment — perfect for exterior decks, patios, and pool surrounds. In stock and ships nationwide — order Cumaru decking online or call 1-844-674-4455 for expert guidance.

5/4 x 6(1"×5.5" actual)[25.4mm × 139.7mm]
Contractor Trusted
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Ships Nationwide
SKU: CUMA-54X6-E4E-SB-L1

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Select profile, grade, and length below to see live pricing

Discover the Advantages of Cumaru in an E4E Profile for Your Decking Needs

Eased-Edge (Standard)

Select and Better is our standard grade

Length Guide

Available lengths: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22′

Estimated Shipping Weight
Weight per linear foot:2.67 lbs/LF
1' board:3 lbs

5/4x6 Cumaru Wood Decking — Complete Guide

Everything you need to know about eased-edge cumaru decking

About 5/4x6 Cumaru Wood Decking

Cumaru lumber, renowned for its exceptional durability and beauty, makes an excellent choice for decking applications. Known scientifically as Dipteryx odorata, this tropical hardwood offers remarkable strength and resistance to the elements, making it ideal for both residential and commercial decking installations. Its E4E (S4S) profile provides a smooth finish, enhancing aesthetic appeal while allowing for effective fastening, which results in a stable and attractive surface for outdoor spaces.

  • Highly durable and strong, perfect for decking applications.
  • Exceptional resistance to weathering, rot, and insect activity.
  • E4E profile ensures a smooth finish with reduced splintering.
  • Transforms outdoor areas into beautiful, functional spaces.

Key Benefits

Unmatched Durability

Cumaru's high Janka hardness rating of 3330 ensures it withstands heavy foot traffic and impacts, making it perfect for busy outdoor spaces.

Weather Resistance

Naturally resistant to moisture, rot, and pests, Cumaru maintains its integrity and appearance even in harsh climates.

Low Maintenance

With its robust nature and natural resistance to the elements, Cumaru requires minimal upkeep, allowing for more enjoyment and less worry.

Technical Specifications

Janka Hardness

3330

Density

74 lbs/cu ft

Durability Rating

Class 1 (very durable)

Dimensional Stability

Excellent dimensional stability under varying moisture conditions.

Installation Guide

Difficulty:
Moderate

Key Tips:

  • Use stainless steel or composite screws for optimal fastening.
  • Leave appropriate spacing between boards for expansion and contraction.
  • Ensure proper ventilation beneath the deck to minimize moisture buildup.

Recommended Tools:

Drill
Circular saw
Measuring tape
Level

Maintenance & Care

Cleaning

Regular sweeping and occasional washing with mild soap and water will keep your Cumaru deck looking pristine.

Finishing

Apply a penetrating oil finish to enhance color and provide additional UV protection.

Weathering

Over time, untreated Cumaru will weather to a silver-gray patina; regular maintenance can help retain the original color.

Frequently Asked Questions

A 5/4x6 Cumaru board weighs approximately 2.67 lbs per linear foot. Cumaru has a density of about 68 lbs/ft³, making it one of the densest commercially available hardwoods. Always factor weight into your structural and shipping calculations.

Yes — Cumaru is rated Durability Class 1 (Very Durable) and is naturally resistant to rot, decay, insects, and fungal attack without chemical treatment. It is Class B fire-rated and performs exceptionally well in full exterior exposure including decking applications. While ground contact is possible, we recommend elevating Cumaru boards at least 6" above grade for maximum lifespan.

Cumaru outperforms composite in hardness (3,540 vs ~200 Janka), lifespan (up to 50+ years vs 25-30 years), and heat resistance. Unlike composites, Cumaru won't melt, warp in extreme heat, or fade significantly. While initial cost is similar ($8-15/LF installed), Cumaru costs less over its much longer lifetime. Composites do offer lower upfront maintenance.

Cumaru requires minimal maintenance. Without treatment, it naturally weathers to an elegant silver-gray patina over 6-12 months. To maintain the original warm brown color, apply a UV-inhibiting penetrating oil (like Ipe Oil or Penofin) once or twice annually. Cleaning involves periodic washing with a mild soap solution. No sanding, staining, or sealing is required for structural durability.

Cumaru is DIY-friendly with proper preparation. Key requirements: (1) Always pre-drill all screw holes — Cumaru is too hard for direct screwing. (2) Use only 305 or 316 stainless steel fasteners — standard hardware will corrode and stain. (3) Face-screw with stainless steel trim-head screws. (4) Allow boards to acclimate on-site for 5-7 days before installation. A compound miter saw with a carbide-tipped blade is recommended.

A nominal 5/4x6 Cumaru board has actual finished dimensions of 1" × 5.5" (25.4 x 139.7 mm). The "5/4x6" is the nominal (rough-cut) size — after kiln drying and precision surfacing, all hardwood lumber finishes slightly smaller. This is standard across the lumber industry, similar to how a nominal 2×4 softwood measures 1.5" × 3.5". Always use the actual dimensions (1" × 5.5") when calculating material quantities and coverage for your project.

We responsibly, legally, and ethically source all our Cumaru. We work only with suppliers who follow responsible forestry practices with full chain-of-custody transparency. Note: We are not FSC certified. Cumaru trees grow naturally in diverse tropical forests and regenerate well under managed harvest. The extremely long lifespan (up to 50+ years) means fewer replacements compared to softwood or composite alternatives, reducing long-term environmental impact.

Shipping & Delivery

Nationwide delivery: We ship to all 50 states via LTL freight, flatbed, or terminal pickup

Typical lead time: 5-10 business days for standard orders (custom milling may add 2-3 weeks)

Shipping estimate: Final freight cost calculated at checkout based on your location and order size

Rush service available: Contact us for expedited milling and shipping options