How to Maintain a Cumaru Deck (Annual Schedule)
Cumaru is roughly 80% as durable as Ipe and lasts 25–35 years in LA's climate with the right maintenance. The maintenance is light — an oiling every 18-24 months keeps the amber tone; leave it alone and it weathers gracefully to silver-grey. Here's the actual annual maintenance schedule we give to clients with Cumaru decks.
Written by
Israel Acquino — Founder & General Contractor · CSLB #964664
Year 1 (after install)
Light cleaning every 3–4 months with a soft brush and water. No pressure washing — high-pressure water can lift surface fibers. If the deck was sealed at install, check the surface in month 6 — if water still beads, the seal is intact. If water absorbs, plan a re-oiling at month 12. If the deck was unsealed at install (common for clients who want to weather to silver-grey), no oiling needed; just light cleaning.
Year 2
Sealed deck: re-oil at month 18-24. Use the same oil specified at install (typically Penofin Red Label, Cabot Australian Timber Oil, or Messmer's UV Plus). Apply with foam roller at the dose specified on the can — typical coverage 200–250 sq ft per quart. Allow 24 hours dry time before walking on. Unsealed deck: still no oiling. Boards should be at the silvering stage — uniform grey color with no spot-rotting (Cumaru rarely spot-rots; this would indicate substructure moisture issues).
Year 3 and beyond
Sealed deck: re-oil every 24 months. The interval extends slightly with each cycle as the wood absorbs less oil — by year 8 you may be at 30-month intervals. Watch for: light cupping on south-facing boards (acceptable up to 1/8 inch), color fade in highest-UV areas (cosmetic only), and any board that feels noticeably lighter when stepped on (potential rot — investigate). Unsealed deck: continues weathering. Year 5+ Cumaru reads as a uniform pewter-grey. Light cleaning continues; no oiling needed.
When to call a contractor
Three triggers. First: visible structural movement — board cupping over 1/4 inch, board lift at the ends, or any joist visibility through a board. Second: spot rot or soft spots — uncommon on Cumaru but occasionally indicates substructure moisture. Third: hardware oxidation — visible rust streaks running down boards. All three indicate substructure issues, not surface issues; surface refinishing won't address them.
Year 15+ refinish considerations
Around year 15-20 (sealed Cumaru) or 18-25 (unsealed), most Cumaru decks benefit from a light surface refinish — light sanding with 120 grit, end-sealing of any exposed end-grain, and re-oiling. Cost: roughly $4–$8 per sq ft. This refresh extends usable life another 10–15 years. By year 30+, most Cumaru decks have either been refreshed once or are approaching the lifecycle threshold for board-level renewal.
Questions homeowners ask