Composite Decking Power Washing Guide

With the arrival of spring, homeowners start cleaning their deck. Composite decking offers an attractive, low-maintenance alternative to natural wood, but requires proper care to keep it looking its best.

When dirt, mildew, and stains accumulate, you may be tempted to use a power washer to restore your composite deck's appearance. But is power washing safe for composite decking materials? What risks does it pose? Are there better ways to clean composite decks without causing harm?

Benefits of Power Washing Composite Decks

Power washing uses pressurized water to remove debris and deeply clean surfaces. When done properly, power washing a composite deck offers benefits like:

• Removes trapped dirt, mildew stains, leaf debris, mud, etc.
• Restores original color that may have faded over time
• Provides a quick and effective deep cleaning solution
• Prevents long-term buildup that can lead to more costly repairs

With the right equipment, technique, and composite decking material, power washing can make a world of difference in the appearance of faded, weathered decking.

Effectively Targets Stains and Grime

Over months or years, composite decks collect pollen, mud, beverage spills, leaf tannins, food grease, bird droppings, and other stubborn substances. These stains can be tricky to remove using standard sweeping, wiping or mopping.

Power washing's pressurized water and specialty cleaning solutions can tackle this grime buildup more effectively. The pressure helps dislodge and blast away residue while detergents dissolve organic stains.

Restores Faded Color and Texture

Factors like sun exposure, weathering, mold, and everyday use take a toll on composite materials over time. The decking's original rich color starts to fade and the surface texture looks worn.

Gently power washing a composite deck helps remove this top layer of faded material so the brighter color underneath is revealed. It also restores a more evenly textured appearance.

Risks of Power Washing Composite Decking

While offering benefits, power washing composite deck boards also carries risks including:

• Deck damage if pressure is too high
• Compromising protective exterior finish
• Pushing water into delicate interior areas
• Injury if proper precautions not taken

To understand these risks, it helps to know what composite decking is made of and how it differs from natural solid wood.

Can Damage Softer Deck Boards

Composite decking contains wood fibers , plastic polymers, minerals and other materials bonded together under heat and pressure. This composition makes most composite decking softer and more flexible than solid wood .

While durable, under too much pressure composite materials can scratch, gouge , or become waterlogged . Power washers generate water pressures ranging from 1500 to 4000 PSI. Even at lower settings, this can damage delicate decking with repeat exposure.

Pushes Water Into Hollow Parts

Many modern composite boards feature hollow or channel-like interiors to improve drainage--any trapped moisture can encourage mold growth. Focused high-pressure water blast straight down and then under the deck.

Over time, this moisture intrusion rots the deck's subframe and fasteners. Repeated pressure-washing accelerates deterioration of surrounding structural components.

Preparing to Power Wash a Composite Deck

If attempting do-it-yourself deck power washing, careful prep work helps minimize risks:

• Check warranty guidelines regarding power washing
• Clear furniture, planters and decor off deck
• Have necessary supplies ready - cleaner, brush, etc.
• Use eye, ear and skin protection

Review Decking Warranty First

Most composite decking manufacturers recommend avoiding power washers entirely . Trex, TimberTech and other brands specifically state power washing voids the warranty if surface damage results.

So before pulling the trigger, double check warranty terms. Get any power washing exclusions or damage disputes handled upfront instead of losing coverage later.

Clear Surrounding Area First

Remove patio furniture, flower pots, grills and other items from the deck area. It prevents cleaners and debris splashing onto treasured possessions. Cover immovable fixtures like walls or railings with tarps or plastic sheeting.

Sweep loose particles off the deck before washing. Pick up any toys, tools or other objects that could turn into dangerous projectiles.

Power Washing Process and Tips

When ready to start power washing, utilize these methods to help avoid deck damage:

• Start at lowest pressure setting and increase gradually
• Adjust wand nozzle for wide-spray fan pattern
• Work perpendicular to board direction to limit water intrusion
• Keep spraying nozzle 6-12 inches from deck surface

Start at Reduced Pressure

Rather than immediately using full pressure, begin power washing the composite decking at the washer's lowest setting. Slowly increase pressure until reaching the minimum needed to effectively lift dirt and stains after testing a small inconspicuous area first.

Use a Wide-Fanned Nozzle

Swap out the pressure washer wand's intense zero-degree jet nozzle for a wider fan spray setting instead. This distributes impact force over a larger deck board area instead of narrowly focused.

Foaming sprayer attachments also help temper pressure while helping cleaning solutions stick to vertical surfaces longer.

Work Perpendicular to Deck Boards

Direct the power spraying wand perpendicular to the length of the deck planks whenever possible. This makes it harder for water to penetrate between gaps or down interior channels.

Angle the spray to prevent blasting directly into board seams or ends. Adjust spray angle periodically to avoid excessive focus on any single area.

After Power Washing Care

Proper care after power washing protects deck integrity and appearance:

• Inspect for damage and reduce pressure if needed
• Let deck fully dry before applying treatments
• Apply composite deck cleaners and sealants if desired
• Replace any cracked, broken or warped boards

Inspect Between Passes

Take breaks between wash cycles to inspect for damage instead of continually power washing. Examine decking for protective coating removal, surface roughening, mold lines or color change.

If notable degradation has started, stop power washing altogether. Let the deck fully dry then re-evaluate less aggressive cleaning options instead to avoid premature replacement.

Allow Deck to Dry Completely

Before applying any waterproofing protectants, specialized cleaners, or sealants--allow deck to dry for 48-72 hours after power washing. Trapped moisture under treatments can encourage hidden fungal growth and other problems.

Use a moisture meter on several deck board areas confirming readings are equalized overnight after the deck appears dry on the surface.