How to Clean Composite Decking with a Pressure Washer
Can you power wash composite decking? Yes, where the decking manufacturer permits it, but the pressure, nozzle and working distance matter. For NeoTimber® boards, the published care guide allows pressure washing at no more than 3,100 PSI, using a fan attachment at least 250 mm from the surface.
That figure is a maximum limit, not a target setting. Start gently and use the lowest effective pressure. If you are using a cleaning product, follow its instructions too: a lower limit may apply. Do not transfer NeoTimber’s guidance to another brand without checking that manufacturer’s requirements.
For everyday dirt, you may not need a pressure washer at all. Warm soapy water and a soft-bristled brush are a useful starting point. This guide explains how to prepare the deck, wash carefully and deal with marks without unnecessarily aggressive cleaning.
Check These Settings Before You Start
| Item | What to check |
|---|---|
| Pressure | No more than 3,100 PSI; begin at a lower effective setting. |
| Nozzle | Use a fan attachment, not a concentrated jet. |
| Distance | Keep at least 250 mm between the nozzle and board surface. |
| Cleaning direction | Work along the length of the boards. |
| Cleaner restrictions | Follow both the decking and cleaner instructions; use the more restrictive limit. |
Check the current NeoTimber® maintenance guide before starting. This article uses “power washing” to mean pressure washing; it does not recommend heated-water or steam equipment.
1. Clear the Deck and Remove Loose Debris
Lift furniture, planters and other movable items rather than dragging them across the surface. This gives you room to work and avoids moving grit beneath furniture feet.
Sweep away leaves, dust and loose dirt with a soft-bristled brush. Pay attention to board gaps and places where debris collects. Removing loose material first makes it easier to see which areas actually need further cleaning.
Check the surface for damage before washing. If boards or fixings need attention, address the issue before directing water at the affected area.
2. Try a Gentle Clean First
Apply warm soapy water and work over the surface with a soft-bristled brush. Clean along the boards, then rinse away loosened dirt. For a routine clean, this may be all that is required.
If marks remain, identify what you are trying to remove before increasing the cleaning intensity. Grease, surface growth and changes in colour do not necessarily respond to the same treatment. Refer to the care guide for the selected board range.
Low-maintenance decking still needs cleaning, but it does not benefit from unnecessary abrasion. Avoid using a wire brush or an unapproved treatment simply because a stain is persistent.
3. Set Up the Pressure Washer Carefully
If pressure washing is appropriate, fit the fan attachment and check the equipment instructions. Test a small, inconspicuous area at a low setting before moving across the main deck.
Maintain the required nozzle distance and keep the spray moving. Do not move closer to attack a stubborn mark or hold a concentrated stream on one spot. Excessive pressure or poor technique can mark or damage the surface.
If you notice a change in texture or appearance, stop and reassess the method. Increasing pressure is not the right response to every remaining stain.
4. Use a Fan Spray and Work Along the Boards
A fan attachment spreads the flow over a wider area than a narrow jet. It is still important to control the pressure and distance: a fan nozzle alone does not prevent damage.
Work in manageable sections, following the length of the boards with steady passes. Rinse away loosened dirt instead of allowing it to collect on an adjacent section. Keep the working area clear so you can maintain an even distance.
Grooves and textured surfaces may need additional brushing to release trapped debris. Take time with those areas rather than assuming a stronger jet is necessary.
5. Use Specialist Composite Cleaner According to Its Label
For suitable stains, NeoTimber® offers Owatrol Compo-Clean. Check compatibility with your board range and follow the current product label, including application, protective equipment and rinsing instructions.
Compo-Clean is ready to use and should not be diluted. Owatrol’s published directions specify applying it, allowing approximately five minutes of working time before brushing, and rinsing thoroughly. Do not apply it in direct sunlight or to a hot surface.
The cleaner’s pressure limit is lower. Owatrol specifies a maximum of 50 bar when pressure washing to rinse Compo-Clean. Do not use NeoTimber’s general 3,100 PSI ceiling for this step. Follow the lower cleaner limit and retain the decking manufacturer’s nozzle and distance requirements.
Consult the Owatrol directions for use before application. If the cleaner and board instructions differ on equipment or treatment, ask the supplier to confirm a compatible method rather than improvising.
Finish with a Thorough Rinse and Inspection
Remove cleaner and loosened dirt as directed, then allow the surface to dry before assessing the result. Wet boards can look different from dry boards, so avoid repeating an aggressive treatment simply because the finish appears uneven while damp.
Replace furniture carefully once the deck is ready for use. Keep leaves and debris under control between cleans to reduce the amount of work needed next time.
Power Washing Composite Decking FAQs
Can you power wash composite decking without damaging it?
You can reduce the risk by following the exact board-care instructions, testing a small area and using the permitted nozzle, pressure and distance. Approval to pressure wash does not mean every machine setting or technique is suitable.
Is 3,100 PSI the best setting for cleaning composite decking?
No. It is NeoTimber’s published general maximum, not the recommended starting setting. Use the lowest effective pressure, and follow any lower limit specified for your cleaning product.
Can I clean composite decking without a pressure washer?
Yes. For NeoTimber® boards, warm soapy water and a soft-bristled brush are recommended for routine cleaning. Rinse away the dirt and follow the care guide for any remaining stains.
Should I dilute Owatrol Compo-Clean?
No. Owatrol describes Compo-Clean as ready to use. Follow its current label for application and rinsing rather than treating it as a concentrated detergent.
How often should I clean my composite deck?
NeoTimber® recommends routine cleaning every three to six months. Check the surface between cleans and remove spills or accumulating debris promptly using the appropriate method.
Keep Your Deck Clean with the Right Method
Start with the gentlest suitable approach, use pressure washing only within the relevant instructions and treat specialist cleaners as a separate step with their own requirements. Regular care can help keep your deck looking its best without unnecessary force.
Read the full composite decking care guide for further advice, or contact NeoTimber® if you are unsure which method suits your boards.
