How to Clean Hardwood Decking Without Damaging the Wood

Introduction

Cleaning your hardwood deck is one of the most important and most mishandled maintenance tasks. Ipe, Cumaru, Garapa, and other tropical hardwoods require specific products and techniques — using the wrong cleaner or too much pressure can damage the surface permanently.

Key Takeaway: Use a purpose-formulated deck cleaner (not bleach, not TSP at full strength, not a pressure washer at high PSI), scrub with the grain, and rinse thoroughly.

What NOT to Use on Hardwood Decks

Chlorine bleach: Bleach lifts the grain of tropical hardwoods and can cause uneven discoloration. It's effective at killing mildew but destructive to wood fibers — avoid on tropical hardwoods.

Undiluted harsh chemicals: Strong degreasers and highly acidic or alkaline products degrade wood surface fibers.

Pressure washer at high PSI: Pressure washing above 1,200–1,500 PSI can raise grain, fuzz the surface, and drive water into gaps and penetrations. If using a pressure washer, keep it at low pressure with a fan tip — never a pinpoint tip.

Steel wool or wire brushes: These leave metal fibers in the wood that rust and stain.

Recommended Cleaning Approach

Step 1: Sweep and Clear

Remove all furniture, planters, and debris. Sweep thoroughly to remove loose dirt and leaves.

Step 2: Pre-Wet the Deck

Rinse the deck with water before applying cleaner. Pre-wetting prevents the cleaner from absorbing too quickly.

Step 3: Apply Deck Cleaner

Use a purpose-made tropical hardwood deck cleaner or a diluted oxalic acid-based product. Apply with a brush, roller, or pump sprayer — follow product dilution instructions.

Step 4: Scrub With the Grain

Use a stiff-bristle brush (nylon — not wire) and scrub in the direction of the wood grain. Working with the grain removes dirt from between fibers without damaging the surface.

Step 5: Rinse Thoroughly

Rinse completely with clean water. Any cleaner residue left on the surface can interfere with oil absorption. Make sure all cleaning product is removed from between board gaps.

Step 6: Allow to Fully Dry

Wait 48 hours of dry weather before applying oil or any finish. See our oil application guide for next steps.

How Often to Clean

• Minimum: Once per year, ideally in spring
• Coastal climates: Every 6 months, with rinse-downs every few months to remove salt accumulation
• High-shade areas: Every 6 months — shade promotes mold and mildew

Dealing with Specific Issues

Mold and Mildew

Mildew appears as dark spots or streaking. A deck cleaner with a mildewcide component is most effective. For severe cases, see our mold removal guide.

Tannin Staining

Tannins from Ipe can stain concrete and other surfaces. Clean promptly with an oxalic acid solution.

Iron or Rust Staining

Iron staining appears as dark spots around fasteners or from metal furniture. An oxalic acid deck brightener will typically remove iron stains effectively.

FAQ

Can I use a pressure washer on Ipe?

Yes, but carefully. Use a fan tip (never pinpoint), keep distance at 18–24 inches, and limit pressure to 1,200–1,500 PSI maximum. High pressure damages the surface grain of any wood — tropical or not.

Does cleaning prepare the deck for oiling?

Yes — a clean, dry deck surface is required before any oil application. Oil applied over dirt, mildew, or residue will result in a poor finish.