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.
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.
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.