How to Jet Wash a Patio and Decking Without Damage
Step-by-step advice on jet washing patios, paths and decking in the UK, with pressure settings, technique, safety and aftercare to avoid damage.
A pressure washer can transform a green, slippery patio in an afternoon. It can also etch stone, strip pointing and leave stripes if you use it carelessly. A little technique and the right settings make all the difference.
Choose the day and prepare
- Pick a dry, mild day so surfaces dry afterwards. Avoid frost, which can freeze run-off and create a slip hazard.
- Clear furniture, pots and toys from the area.
- Sweep loose debris and pull out weeds from joints.
- Protect plants and nearby surfaces by wetting them, moving pots or covering with sheeting.
- Check for hazards such as electrical sockets, lighting and drains. Keep spray away from sockets and consider covering.
Know your surface
Concrete and block paving
Tough enough for most pressure washers. Use a surface cleaner attachment for an even finish. Re-sand the joints afterwards.
Natural stone
Sandstone, limestone and old riven slabs are softer. Use lower pressure, a wide fan nozzle and keep the lance moving. Test a hidden area first.
Porcelain and tiled patios
Fairly robust, but pressure should still be moderate to avoid damaging grout lines. Follow the manufacturer's guidance if you have it.
Decking
Timber is soft. Use low pressure, a wide fan, and work along the grain. Hold the nozzle further away to avoid raising fibres. Decking cleaner products can reduce the need for pressure.
Resin-bound and tarmac
These can be damaged by high pressure and may be better cleaned with a soft brush and a mild cleaner.
Technique
- Pre-treat algae and moss with a suitable patio cleaner, following the label and leaving it for the recommended time.
- Start at the top of a slope and work downhill so dirty water runs away.
- Keep the nozzle a consistent distance, usually 20 to 30cm, and move at an even speed in overlapping strokes.
- Work in sections, such as a metre at a time, to avoid streaks.
- Use a surface cleaner for large areas, which gives a uniform finish and reduces splash.
- Rinse thoroughly to remove loosened dirt and chemical residue.
- Let it dry, then sweep sand into the joints if needed.
Wear eye protection and sturdy shoes. High-pressure water can cut skin, so never point it at anyone or at your own feet.
Common mistakes
- Using a narrow pencil jet on soft stone.
- Holding the lance too close to the surface.
- Washing in bright sun, which makes the surface dry unevenly and leaves marks.
- Forgetting to re-sand the joints, which lets weeds in.
- Cleaning decking against the grain.
Aftercare
- Treat with an algae preventer after cleaning, to slow regrowth in shady spots.
- Seal if appropriate, applying on a fully dry, clean surface.
- Treat decking with oil or stain once dry.
- Sweep regularly and clear leaves promptly; see autumn leaf clearance.
DIY or hire?
Hiring a pressure washer is cheap, and the job is within most people's ability. If you have a very large area, delicate stone or limited time, a professional with a surface cleaner will be quicker and often more even. Typical prices are covered in patio cleaning cost in the UK.
On Compito you can search by postcode, compare ID-verified local providers, and send a request with photos, size and surface type. You can message providers to confirm the method before accepting an offer and paying online. See how it works.
Worked example: a 25m2 patio after winter
A sandstone patio has turned green and slippery. The homeowner hires a pressure washer for the weekend, sweeps off leaves, applies an algae treatment and waits the recommended time. They test a corner with a wide fan nozzle at low pressure, then work down the slope in overlapping strokes, rinse, and let the surface dry. Re-sanding the joints the next day finishes the job. The result is a clean, even surface, and a few hours of work spread across the weekend. Rushing at high pressure with a narrow jet would have left stripes and roughened the stone.
Surface and setting guide
| Surface | Pressure | Nozzle | Notes |
|---|---|---|---|
| Concrete slabs | Higher | Fan or surface cleaner | Re-sand joints |
| Block paving | Medium | Fan or surface cleaner | Watch joint sand |
| Sandstone, limestone | Low | Wide fan | Test first |
| Porcelain | Medium | Fan | Mind grout |
| Softwood decking | Low | Wide fan | Along grain |
Safety and neighbours
- Keep children and pets away from the area and run-off.
- Do not spray near sockets, lights or open doors.
- Be aware of splash and spray drifting onto neighbours' property.
- Avoid washing treatment chemicals into drains or ponds.
- Take care on wet surfaces, which can be slippery.
Special cases
- Rentals and flats. Check the agreement and consider noise and water use before working on shared patios.
- Listed buildings and old stone. Seek advice, as pressure can cause lasting damage.
- Sloping patios. Work carefully to avoid run-off into airbricks or doorways.
- Moss and algae in shade. Cleaning will need repeating, so reduce the cause where you can; see planting for shade.
What to do if it goes wrong
If you notice lines, etching or loose joint material, stop and let the surface dry. Re-sand joints and consider asking a professional about repair or sealing options.
Frequently asked questions
When is the best time to jet wash a patio?
Spring is popular, once the worst of the wet and frost has passed. Autumn also works, before slippery winter conditions begin.
Will jet washing remove all stains?
Algae and general dirt usually come off well. Oil, rust and deeply set stains may need specialist cleaners or may not fully disappear.
Can I jet wash decking?
Yes, with care. Use low pressure and work along the grain, and let it dry fully before oiling or staining.