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1x3 Cumaru Shiplap Soffit board profile diagram
Soffit

1x3 Cumaru Shiplap Soffit

This 1x3 Cumaru Shiplap soffit board 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 overlapping shiplap profile sheds water naturally and creates a classic, weather-resistant look for eave linings, ceilings, and covered areas. In stock and ships nationwide — order Cumaru soffit online or call 1-844-674-4455 for expert guidance.

1 x 3(0.75"×2.5" actual)[19.0mm × 63.5mm]
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Ships Nationwide
SKU: CUMA-1X3-SHIP-SB-L1

Configure Your Order

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

Durable, Moisture-Resistant Shiplap Profile in 1x3 Size

Shiplap

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:0.91 lbs/LF
1' board:0.9 lbs

1x3 Cumaru Shiplap Soffit — Complete Guide

Everything you need to know about shiplap cumaru soffit

About 1x3 Cumaru Shiplap Soffit

Cumaru lumber, known for its exceptional durability and stability, is an ideal choice for soffit applications. The unique characteristics of this wood species, combined with its shiplap profile, provide a perfect blend of functionality and aesthetic appeal for exterior overhead spaces. Shiplap's design not only ensures clean lines that enhance visual quality but also allows for better ventilation, making it well-suited for soffits.

  • Exceptional dimensional stability under various climatic conditions
  • High durability, resistant to moisture and decay
  • Compatible with ventilation requirements for optimal airflow

Key Benefits

Natural Resistance to Elements

Cumaru exhibits remarkable resistance to rot, insects, and humidity, making it suitable for outdoor applications where it is exposed to moisture and pests.

Aesthetic Appeal

With its rich color variations ranging from golden yellow to deep brown, the grain pattern of Cumaru adds natural beauty to soffit designs, enhancing architectural features.

Sustainable Choice

Cumaru is harvested from responsibly managed forests, providing an eco-friendly option for construction with a lower environmental impact.

Technical Specifications

Janka Hardness

3330

Density

65 lbs/ft³

Durability Rating

Class 1 (very durable) according to natural durability classifications

Dimensional Stability

Highly stable; minimal shrinkage and swelling, ideal for varying environmental conditions

Installation Guide

Difficulty:
Moderate

Key Tips:

  • Ensure proper ventilation spacing to prevent moisture build-up
  • Utilize stainless steel fasteners to prevent corrosion within exterior conditions
  • Leave adequate expansion gaps between boards for optimal performance

Recommended Tools:

Power saw
Drill
Safety goggles
Tape measure

Maintenance & Care

Cleaning

Clean regularly with a gentle detergent and water solution to maintain appearance. Avoid harsh chemicals that could damage the finish.

Finishing

To maintain the natural look and enhance UV resistance, consider applying a UV-blocking sealer.

Weathering

Cumaru will weather to a gray patina over time unless regularly maintained with sealers.

Frequently Asked Questions

A 1x3 Cumaru board weighs approximately 0.91 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 A fire-rated and performs exceptionally well in full exterior exposure including soffit applications. While ground contact is possible, we recommend elevating Cumaru boards at least 6" above grade for maximum lifespan.

Cumaru outperforms composite in hardness (3,330 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 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 1x3 Cumaru board has actual finished dimensions of 0.75" × 2.5" (19.0 x 63.5 mm). The "1x3" 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 (0.75" × 2.5") 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

1 x 3 Cumaru Shiplap 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.

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 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 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 1 x 3 shiplap profile creates an overlapping joint with a distinctive shadow line between boards. Popular for siding, accent walls, and architectural cladding applications. 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.

Janka Hardness

3,330 lbf

Service Life

50+ years

Durability

Very Durable

Fire Rating

Class A

1 x 3 Cumaru Soffit — Frequently Asked Questions

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.

Use 305 or 316 stainless steel screws for all Cumaru installations — never use galvanized or coated deck screws, which will corrode and stain the wood. Pre-drill every hole using a countersink bit sized for your screw. For 1 x 3 boards, place screws approximately 1" from each edge and 3/4" from board ends. A combination drill/driver with a clutch setting prevents over-driving into this extremely hard wood.

Cumaru soffit pricing varies by size, profile, grade, and board length. 1 x 3 Shiplap 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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