Greene County
Pressure Washing

Composite deck

Composite boards don’t fur like wood, but each maker sets its own rules for pressure washers, and breaking them can void the warranty. Find the brand of your boards before you start.

Within the brand’s limit

Method
Soap and a soft brush. A pressure washer only within the brand’s limits.
Pressure
Trex: 3100 psi max1. TimberTech: 1,500 psi max, rinse only2. Fiberon: under 3,000 psi3.
Cleaners
Whatever your brand’s care guide names. No bleach or acid on Trex.

Pressure or soft washing

Soft wash Cleaner goes on first, a soft brush does the scrubbing, and a garden hose does the rinsing.
distance
Pressure wash A machine pushes water through a nozzle. The tip, the distance and the angle set how hard it hits. Within the brand’s limit

The three big brands disagree, so the brand of your boards decides the method. Trex allows a pressure washer with a fan tip on its Transcend, Enhance and Select decking1. TimberTech allows one for rinsing only2. Fiberon says to use extreme caution3.

Trex does not recommend a pressure washer on early-generation Trex decking, and says doing so will void the warranty for any condition the washing causes1.

Nozzle and pressure

40° 25° 15° 0°
Spray angle by nozzle tip. A narrow angle puts the same water on one small spot; a wide fan spreads it out. This guide’s sources name no tip angle. Your maker’s care guide sets the limit.

Trex: no greater than 3100 psi, with a fan attachment, keeping the fan tip no closer than 8 inches to the boards1. Trex says more than 3100 psi could damage the boards and void the warranty1.

TimberTech: rinsing only, with a recommended maximum of 1,500 psi and a fan tip2. Spray along the grain pattern, never across the width of the board2.

Fiberon: under 3,000 psi at 10 inches above the deck, washing in the direction of the grain3.

Cleaners to use and avoid

Use

  • The cleaner your brand’s care guide names. TimberTech’s guide lists its own recommended cleaners2.
  • A soft brush. TimberTech says a stiff natural-fiber deck brush can dull its composite boards2.

Avoid

  • Products containing bleach or acid on Trex, which will lighten the surface1.
  • On TimberTech, generic composite deck cleaners. Its guide names several, including Corte Clean, Thompson’s Water Seal Oxy Action and Olympic Deck Cleaner2.
  • Spraying across the boards2.

Protect plants and keep runoff out of drains

Cleaning chemicals can damage plants and grass. The Brick Industry Association’s advice holds for any surface: protect nearby plants, and where needed keep the cleaning solution and runoff off plants and the soil around them4. Soaking beds with plain water before and after, and covering what you can, is the practical version of that.

Street drains are not sewers. EPA reminds people that storm drains lead directly to local waterways, not to treatment facilities. Its tips for washing outdoors: use biodegradable, phosphate-free, water-based detergents, use as little as you can, wash on a driveway or yard rather than in the street, and send the wash water onto grass or gravel5. In Greene County, polluted runoff that enters the storm sewers is often discharged into local rivers and streams without treatment6, and Beavercreek asks residents not to dump anything down a storm sewer or drain7.

If you see suds, a rainbow sheen or an odd color in a ditch, stream or storm drain, Greene County asks you to report it to the County Engineer’s Office at 937-562-75008.

Common damage

  • Damaged boards and a void warrantyGoing over the brand’s pressure limit can damage boards and void the warranty1.
  • A lightened surfaceBleach and acid lighten Trex boards1.
  • A dulled surfaceStiff natural-fiber brushes dull TimberTech composite2.

When not to pressure wash at all

  • On early-generation Trex decking1.
  • Above your brand’s limit, or closer than its minimum distance.
  • When you can’t tell which brand your boards are. Use soap, water and a soft brush until you find out.

Step by step

  1. Identify the boardsFind the brand and product line. Check the care guide and warranty for pressure washer rules.
  2. Sweep and clearMove furniture and sweep out debris from the gaps.
  3. Wash with the right cleanerUse the cleaner your brand recommends and a soft brush.
  4. Rinse along the grainRinse with a hose, or a pressure washer within the brand’s limit, fan tip, moving along the boards.

Before you start, read the safety page. If the job looks bigger than you want to take on, DIY or hire lays out what each way involves.

Sources

Every superscript number on this page points to one of these. Each was read on the date shown.

  1. How To Clean Composite Decking Trex. Checked 2026-10-26.
  2. Care & Cleaning Guide: Decking and Railing TimberTech (AZEK). Checked 2026-10-26.
  3. Deck Maintenance & Care Fiberon. Checked 2026-10-26.
  4. Technical Note 20: Cleaning Brickwork (August 2018) Brick Industry Association. Checked 2026-10-26.
  5. Stormwater Best Management Practice: Vehicle Maintenance and Washing (EPA-832-F-21-032F) U.S. Environmental Protection Agency. Checked 2026-10-26.
  6. Stormwater Basics Greene County, Ohio. Checked 2026-10-26.
  7. FAQs: Stormwater Program City of Beavercreek, Ohio. Checked 2026-10-26.
  8. Illicit Discharge & Illegal Dumping Greene County, Ohio. Checked 2026-10-26.