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5/4x4 Cumaru Tongue & Groove Siding board profile diagram
Siding

5/4x4 Cumaru Tongue & Groove Siding

This 5/4x4 Cumaru siding board (Tongue & Groove profile) offers unmatched exterior cladding longevity, backed by Cumaru's 3,330 Janka hardness and a natural lifespan of up to 50+ years. The interlocking tongue and groove profile creates tight, seamless joints for exterior cladding and accent walls, with no visible fasteners on the finished surface. In stock and ships nationwide — order 5/4x4 Cumaru siding boards online or call 1-844-674-4455 for expert guidance.

5/4 x 4(1"×3.5" actual)[25.4mm × 88.9mm]
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Ships Nationwide
SKU: CUMA-54X4-TG-SB-L1

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

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:1.70 lbs/LF
1' board:1.7 lbs

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5/4x4 Cumaru Tongue & Groove Siding — 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 5/4x4 Cumaru Wood for Your Siding?

As exterior cladding, Cumaru siding provides a weather-tight barrier with exceptional impact resistance. The dense grain resists dents, hail damage, and woodpecker damage far better than cedar, pine, or fiber cement alternatives. Properly installed 5/4x4 Cumaru siding 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 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.

5/4x4 Cumaru Siding — Installation & Coverage Specs

  • Recommended joist spacing: 16"–24" on center for 5/4x4 boards (1" actual thickness)
  • Fastener placement: Secure per profile requirements, one fastener per joist minimum
  • 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 siding surface (3.5" 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

5/4x4 Cumaru Siding — Frequently Asked Questions

5/4x4 Cumaru siding 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.

5/4x4 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.

5/4x4 Cumaru siding pricing varies by profile, grade, and board length. 5/4x4 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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