How to Clean a Deck or Patio for Summer

After months of rain, your deck or patio is probably showing the effects — moss in the cracks, mildew on the surface, leaf stains, and a general layer of grime. This is especially true in the Pacific Northwest, where Oregon's extended rainy season from October through May gives mold, moss, and algae ample time to establish themselves on every outdoor surface.

The good news is that bringing your outdoor space back to life is a satisfying weekend project. This guide covers cleaning methods for every common deck and patio material, with specific attention to the challenges Oregon homeowners face.

Preparation

Before you start scrubbing, take these steps:

1. Clear the area completely — move all furniture, planters, grills, and decorations off the deck or patio.
2. Sweep thoroughly — remove leaves, pine needles, dirt, and loose debris. Pay attention to gaps between boards where debris collects.
3. Check for damage — look for loose boards, popped nails, cracked concrete, or damaged pavers. Address structural issues before cleaning.
4. Protect surrounding plants — wet down adjacent plants and cover delicate landscaping with drop cloths. Even eco-friendly cleaners can stress plants.
5. Check the weather — plan for a cloudy day or work in the shade. Direct sun dries cleaning solutions too quickly. You also need 24 to 48 hours of dry weather after cleaning for the surface to dry properly.

Cleaning Wood Decks

Wood decks (cedar, redwood, pressure-treated pine) are the most common type in Oregon and the most susceptible to moisture damage.

What You Need

• Oxygen bleach (OxiClean or similar) — not chlorine bleach
• Stiff bristle brush or deck brush
• Garden hose with spray nozzle
• Bucket
• Pressure washer (optional, low PSI only)

Cleaning Steps

1. Mix oxygen bleach according to package directions in a bucket of warm water.
2. Wet the deck with a garden hose.
3. Apply the cleaning solution generously to a manageable section (about 10 square feet at a time).
4. Let it sit for 10 to 15 minutes — do not let it dry.
5. Scrub with a stiff brush working in the direction of the wood grain.
6. Rinse thoroughly with a garden hose or pressure washer on the lowest effective setting.
7. Move to the next section and repeat.
8. Let the deck dry completely — at least 48 hours before applying stain or sealer.

Pressure Washer Guidelines for Wood

Use extreme caution. Pressure washers can damage wood quickly:

• Stay under 1,500 PSI for softwoods (cedar, pine). Use 2,000 PSI maximum for hardwoods.
• Use a fan tip (25 or 40 degree), never a zero-degree tip.
• Keep the nozzle at least 12 inches from the surface.
• Move in smooth, consistent strokes following the grain.
• Never hold the spray in one spot — it will gouge the wood.

Cleaning Composite Decks

Composite decking (Trex, TimberTech, Fiberon) is low-maintenance but not no-maintenance. Mold and mildew grow on composite surfaces just like on wood, especially in Oregon's climate.

1. Mix warm water with dish soap or a composite deck cleaner.
2. Apply with a soft bristle brush — do not use a stiff or wire brush on composite.
3. Scrub gently and rinse with a garden hose.
4. For mold stains, use a solution of two parts vinegar to one part water, or a composite-safe mold remover.

Do not use: chlorine bleach, sanding, or pressure washers above 1,500 PSI. Check your manufacturer's warranty for approved cleaning methods — some brands void the warranty for pressure washing.

Cleaning Concrete Patios

Concrete is durable but porous, which means it stains and develops mold readily.

Basic Cleaning

1. Sweep the entire surface.
2. Apply a concrete cleaner or a strong solution of oxygen bleach and warm water.
3. Scrub with a stiff push broom or floor brush.
4. Rinse with a garden hose or pressure washer.

Removing Specific Stains

• Oil and grease: Apply kitty litter or baking soda to absorb the oil. Let it sit overnight, then sweep up and scrub with dish soap and hot water.
• Rust: Use a commercial rust remover designed for concrete, or try lemon juice and salt for lighter stains.
• Moss and algae: Apply oxygen bleach solution, scrub, and rinse. For heavy growth, a pressure washer at 2,500 to 3,000 PSI is effective on concrete.

Pressure Washing Concrete

Concrete handles pressure washing well. Use 2,500 to 3,000 PSI with a 25-degree fan tip. Maintain consistent distance and overlap your strokes to avoid leaving lines.

Cleaning Stone and Brick Pavers

Natural stone and brick pavers are common in Oregon patios and walkways.

1. Sweep and remove debris from between pavers.
2. Pull any weeds growing in the joints.
3. Scrub with warm water and a mild detergent using a stiff brush.
4. For algae and moss, use oxygen bleach or a stone-safe cleaner.
5. Rinse thoroughly.
6. Re-sand the joints with polymeric sand if needed — this inhibits weed growth and stabilizes the pavers.

Avoid: acidic cleaners on limestone, marble, or travertine — they etch the surface. Acidic cleaners are safe on granite and slate but always test first.

Dealing with Oregon's Mold and Mildew

Mold, mildew, moss, and algae are the biggest deck and patio challenges in Oregon. The wet climate creates perfect growing conditions.

Prevention

• Trim overhanging branches — they block sunlight and drip moisture onto the deck.
• Keep gaps between boards clear — debris-clogged gaps trap moisture.
• Ensure good drainage — standing water accelerates mold growth.
• Apply a mold-inhibiting sealer annually on wood decks.
• Sweep regularly through the wet season — even monthly sweeping helps.

Why Not Chlorine Bleach?

Many guides recommend chlorine bleach for outdoor mold removal. We do not, for several reasons:

• It damages wood fibers and lightens the color unevenly.
• It kills surrounding plants and grass on contact.
• It does not penetrate as effectively as oxygen bleach against deep mold.
• Runoff contaminates soil and can reach waterways — a serious concern in Oregon's environmentally conscious communities.

Oxygen bleach (sodium percarbonate) is effective against mold, safe for plants once diluted, and breaks down into water and oxygen. It is the better choice in every scenario.

After Cleaning: Sealing and Protection

• Wood decks: After cleaning and 48 hours of drying, apply a waterproof stain or sealer. In Oregon, this should be done annually.
• Concrete: Apply a concrete sealer every two to three years to prevent staining and moisture penetration.
• Stone pavers: Seal with a breathable stone sealer to prevent staining while allowing moisture vapor to escape.
• Composite: No sealing needed — just keep it clean.

Ready for Summer

A clean deck or patio transforms your outdoor living space. A few hours of cleaning and a day of drying is all it takes to go from winter grime to a space that is ready for barbecues, gatherings, and relaxing in the Oregon sunshine.

If you prefer to leave the heavy lifting to professionals, Otesse offers comprehensive home cleaning services that include outdoor spaces. Get a free quote and enjoy the summer without the scrubbing.