5/4x6 Cumaru Tongue & Groove Soffit board profile diagram
Soffit

5/4x6 Cumaru Tongue & Groove Soffit

This 5/4x6 Cumaru soffit board (Tongue & Groove profile) combines the rich grain of Cumaru (Brazilian Teak) with 3,330 Janka hardness, making it ideal for exposed eave linings and covered ceilings that endure for decades. The interlocking tongue and groove profile creates tight, seamless joints for eave linings, ceilings, and covered areas, with no visible fasteners on the finished surface. In stock and ships nationwide — order 5/4x6 Cumaru soffit boards online or call 1-844-674-4455 for expert guidance.

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

Configure Your Order

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

Durable, Moisture-Resistant, and Visually Appealing

T&G

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:2.7 lbs

5/4x6 Cumaru T&G Soffit — Complete Guide

Everything you need to know about t&g cumaru soffit

About 5/4x6 Cumaru Tongue & Groove Soffit

Cumaru lumber, with its exceptional dimensional stability and durability, is ideal for soffit applications. Known for its resistance to moisture exposure, Cumaru not only withstands the elements but also maintains structural integrity over time. The tongue-groove profile allows for seamless installation, enhances ventilation compatibility, and provides a clean aesthetic finish, making it an excellent choice for both functional and visual purposes.

  • Highly durable and moisture-resistant
  • Tongue-groove design for easy installation
  • Provides clean lines and improved ventilation
  • Suitable for various exterior applications

Key Benefits

Exceptional Durability

Cumaru's high Janka hardness rating ensures resistance to wear and tear, making it suitable for demanding exterior applications.

Moisture Resistance

Inherent properties of Cumaru provide resistance against moisture, reducing the risk of warping and decay in soffit installations.

Aesthetic Appeal

The natural variations in grain and color contribute to a visually appealing finish, enhancing the overall design of any structure.

Technical Specifications

Janka Hardness

3330

Density

65 lbs/ft³

Durability Rating

Very durable, resistant to rot and insects

Dimensional Stability

Excellent dimensional stability with minimal shrinkage

Installation Guide

Difficulty:
Moderate

Key Tips:

  • Use stainless steel fasteners to prevent rust
  • Leave appropriate spacing for expansion and contraction
  • Ensure correct ventilation to prevent moisture buildup

Recommended Tools:

Miter saw
Drill or impact driver
Level
Measuring tape

Maintenance & Care

Cleaning

Regularly clean with a mild soap and water solution. Avoid harsh chemicals that can damage the wood's finish.

Finishing

Reapply protective finishes every 3-5 years to maintain appearance and moisture resistance.

Weathering

Cumaru naturally weathers to a beautiful silver-grey color if left untreated, adding to its aesthetic appeal.

5/4x6 Cumaru Tongue & Groove Soffit — 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. A 12-foot 5/4x6 Cumaru board weighs approximately 31 lbs. Always factor weight into your structural and shipping calculations.

5/4x6 Cumaru soffit has an expected service life of up to 50+ years when properly installed. This is 3-5× longer than pressure-treated pine and 2-3× longer than cedar. Cumaru achieves this exceptional longevity through its 3,330 Janka hardness and Class 1 durability rating, providing built-in resistance to rot, decay, insects, and fungal growth without chemical preservatives.

5/4x6 Cumaru soffit pricing varies by profile, grade, and board length. Select and Better grade boards typically range from $4-$12 per linear foot before shipping. While the upfront cost is higher than pressure-treated lumber, Cumaru's up to 50+-year service life makes the lifetime cost per year significantly lower. Use the configurator above for exact pricing, or request a custom quote for large orders.

Yes — 5/4x6 Cumaru wood soffit outperforms composite in hardness (3,330 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 wood decking costs less over its much longer lifetime. Composites do offer lower upfront maintenance, but Cumaru's natural beauty and durability make it the superior long-term investment.

Cumaru is widely considered one of the best woods for 5/4x6 soffit boards. With a 3,330 Janka hardness rating, Class A fire-rated certification, and up to 50+-year lifespan, Cumaru (Brazilian Teak) outperforms nearly every other commercially available wood species. Other excellent options include Cumaru (Brazilian Teak) and Massaranduba (Brazilian Redwood), but Cumaru remains the industry benchmark for premium outdoor hardwood applications.

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

5/4x6 Cumaru Tongue & Groove Soffit — Complete Buyer's Guide

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 5/4x6 Cumaru Wood for Your Soffit?

Cumaru soffit and porch ceiling boards create a warm, premium overhead aesthetic that vinyl and aluminum simply cannot replicate. The natural grain pattern adds architectural character to any covered outdoor space. Properly installed 5/4x6 Cumaru soffit 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 5/4x6 tongue & groove (T&G) profile features interlocking edges that create a seamless, flush surface with no visible gaps. Ideal for porch ceilings, soffit installations, and covered porch floors. 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.

5/4x6 Cumaru Soffit — Installation & Coverage Specs

  • Recommended joist spacing: 16"–24" on center for 5/4x6 boards (1" actual thickness)
  • Fastener placement: Secure per profile requirements, one fastener per joist minimum
  • Board weight: A 12-foot 5/4x6 Cumaru board weighs approximately 31 lbs (2.60 lbs/LF)
  • Coverage: Each 12-foot 5/4x6 board covers 5.5 sq ft of soffit surface (5.5" face width)
  • Pre-drilling required: Always pre-drill in Cumaru — the 3,330 lbf hardness prevents direct screwing

Janka Hardness

3,330 lbf

Service Life

50+ years

Durability

Very Durable

Fire Rating

Class A

5/4x6 Cumaru Soffit — Frequently Asked Questions

5/4x6 Cumaru soffit has an expected service life of 50+ years when properly installed and maintained. This is 3-5x longer than pressure-treated pine and 2-3x longer than cedar. Cumaru achieves this exceptional longevity through its natural density (Janka hardness: 3,330 lbf) and Class 1 durability rating, which provide built-in resistance to rot, decay, insects, and fungal growth — all without chemical preservatives.

5/4x6 tongue & groove Cumaru boards interlock via a milled tongue on one edge and a corresponding groove on the other. Secure each board by blind-nailing through the tongue at a 45° angle using stainless steel ring-shank nails or by face-screwing with countersunk stainless steel screws. Always pre-drill holes in Cumaru to prevent splitting. T&G Cumaru should only be used in covered or semi-protected areas.

5/4x6 Cumaru soffit pricing varies by profile, grade, and board length. 5/4x6 Tongue & Groove boards in Select and Better grade typically range from $4-$12 per linear foot before shipping. While the upfront cost is higher than pressure-treated lumber, Cumaru's 50+ years service life makes the lifetime cost per year significantly lower. Use our online configurator above to see exact pricing for your selected options, or request a custom quote for large orders.

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