Timberline Lumber Company supplies Cumaru tropical hardwood decking at mill-direct pricing from Black Mountain, NC. Near-Ipe hardness at a lower cost, delivered on our flatbed fleet to Greenville, Asheville, Knoxville, and the broader Carolinas–East Tennessee region for residential and commercial decks.
Cumaru (pronounced "koo-MAH-roo") is a dense tropical hardwood that delivers performance remarkably close to Ipe at a significantly lower price point. With a Janka hardness of 3,540 lbf, Cumaru is one of the hardest woods commercially available and has become the go-to choice for builders who want tropical-grade durability without the Ipe premium.
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Color & Appearance
Cumaru heartwood displays a beautiful range from golden-tan to reddish-brown, often with darker streaking that adds character and depth to a finished deck. The grain is typically interlocked, producing a medium to fine texture with a natural luster. Like all tropical hardwoods, Cumaru will weather to silver-gray if left unfinished, or the warm tones can be preserved with annual UV oil treatments.
Cumaru vs. Ipe
The honest comparison: Cumaru is 95% of the wood that Ipe is, at roughly 70% of the cost. Both carry Class 1 durability ratings and Class A fire ratings. Both resist rot, termites, and marine borers. The primary differences are aesthetic — Cumaru trends warmer and more golden, while Ipe runs darker and more chocolate-toned. Cumaru also has slightly more color variation board-to-board, which many homeowners actually prefer for a more natural, less uniform look.
Nominal Sizes and Milling Styles
- 1x6 Pre-Grooved Decking: 5.5" exposed face. Hidden-clip ready. Lengths 8'–20'.
- 1x6 S4S (Square Edge): 5.5" exposed face. Face-screw decking, stair treads, perimeter boards.
- 1x6 Tongue & Groove: 5.0" exposed face. Covered porch ceilings, soffits, paneling.
- 1x4 Decking: 3.5" exposed face. Classic Northeastern architectural profile.
- 1x4 Tongue & Groove: 3.0" exposed face. Covered porch flooring.
- 5/4x6 Pre-Grooved: 5.5" exposed face. Heavy-duty commercial & extreme-load. Lengths 8'–20'.
- 5/4x6 S4S (Square Edge): 5.5" exposed face. Heavy-duty face-screw for commercial & dock applications.
Performance Specifications
| Janka Hardness | 3,540 lbf |
|---|---|
| Density | ~66 lbs/cu. ft. |
| Durability Class | Class 1 — naturally rot-, decay-, and insect-resistant |
| Fire Rating | Class A (ASTM E84) |
| Expected Lifespan | 30–50+ years |
| Grading | Premium Grade |
Fastening Ecosystem
Cumaru's density requires specialized fasteners — pre-drilling is mandatory, and only stainless steel hardware should touch the wood. We supply everything you need; just tell us the profile.
- Hidden Clips (Pre-Grooved profiles): Ipe Clip 175-count Complete Kit covers 100 sq. ft. at 16" o.c. — 5/32" gap, brown finish.
- Face Screws (S4S / Square Edge): #7 × 2-1/4" trim-head stainless. One 350-count box per 100 sq. ft.
- Smart-Bit Pre-Drill & Countersink: #7 (flush) or #8 (countersunk). One per box of screws.
- Pro Plug System (optional, for hidden face screws): 5/16" species-matched plugs with Pro Plug tool.
- End Seal: Wax-based sealer applied immediately to every cut end to prevent checking.
Not sure what you need? Give us a call — we'll spec the hardware to match your deck.
Grading Standards (Tropical Decking Grades)
Cumaru is sold to export quality standards rather than domestic NELMA/NHLA grades. We stock the top tier so boards arrive clean and install-ready.
- Premium / FEQ (First European Quality): Our standard Cumaru grade — clear, sound heartwood milled to tight tolerances for visible decking and dock applications.
- Color Variation: Cumaru shows more board-to-board variation than Ipe, ranging from golden-tan to reddish-brown with darker streaking. Many builders prize this for a richer, more natural deck; rack boards from multiple bundles for the best blend.
- Custom Specifications: Need uniform color or specific clear lengths? Contact us for a select-and-better quote.
Project Documentation by Request
For qualifying Cumaru orders, we can request available species, origin, import, and technical documentation from the supplying mill or distributor.
- Confirm before purchase — documentation varies by species, profile, shipment, and supplier.
- Submittal support — ask us to verify what is retrievable for your architect, GC, or procurement team.
- No blanket certification claim — certification applies only when the specific order and its supporting documents are confirmed.
Contact us early so we can confirm the available documentation before you rely on it in a specification or submittal.
Railings & Accessories
For custom railing profiles and dimensions we use Ipe; contact us for availability. Pair Ipe railing with a Cumaru or Ipe deck for a cohesive tropical-wood exterior.
Cumaru Decking FAQ
Is Cumaru as good as Ipe for decking?
Cumaru is nearly as hard (about 3,540 vs 3,680 Janka) and delivers tropical durability at a lower price. Builders choose it when they want Ipe-class performance without the flagship premium — still far harder than domestic softwoods.
Can Timberline deliver Cumaru to Upstate South Carolina?
Yes. We deliver Cumaru decking to Greenville, Spartanburg, and the I-85 corridor on our own trucks from Black Mountain — typically about 75 minutes — with mill-direct pricing and full-length stock.
What fasteners work with Cumaru?
Dense tropicals need stainless or silicon-bronze fasteners and proper pre-drill. We stock hidden clips, Pro Plug systems, and face screws sized for Cumaru; see our tropical fastener guide for the full hardware list.
Do you stock Cumaru pre-grooved decking?
Yes. We carry S4S, pre-grooved, and T&G Cumaru in standard decking dimensions, with additional sizes available by quote from our mill partners.