Pressure washing garden furniture can seem like the quickest way to shift green algae, winter grime and bird mess. But a pressure washer is a blunt tool if you treat every material the same. Wood, metal and plastic all react differently to high-pressure water. Use too much force, or the wrong nozzle, and you can strip a finish, raise the grain, force water into joints, or even blast away a protective coating. The good news is that with a few simple adjustments you can clean thoroughly without causing damage.

Why Pressure Washing Can Be Riskier Than It Looks

A pressure washer that makes short work of a patio slab can ruin a wooden chair in seconds. Most garden furniture is built with glued joints, dowels, mortise-and-tenon connections or welded seams. High-pressure water finds its way into those gaps and stays there, encouraging rot, rust and loosening. On softwoods, a concentrated jet can gouge the surface and raise the grain, leaving a fuzzy finish that never quite recovers. On metal, it can chip powder coating or force water inside hollow tubes. On plastic, it can etch shiny surfaces or crack aged resin. The trick is to think of your pressure washer as a precision tool, not a blaster. Always start on the lowest setting and test on a hidden area first.

Match the Nozzle and Pressure to the Material

Nozzle choice matters as much as pressure. A 0-degree turbo nozzle is far too aggressive for furniture. Use a 40-degree fan nozzle for delicate work, and keep the pressure as low as your machine allows. If your pressure washer has an adjustable lance, start at the minimum and work up only if needed. Here is a quick guide:

• Wood: Use a 40-degree nozzle, keep pressure under 60 bar if adjustable, and hold the wand at least 30cm away. Never use a turbo nozzle. For teak, oak or acacia, a garden hose and soft brush will often do a better job.
• Metal: Check for rust and chipped paint first. Use a 25-degree nozzle at low pressure, and avoid aiming directly at welds, hinges or joints. Aluminium can dent; powder coating can chip. Dry immediately to prevent water spots.
• Plastic: Use a 40-degree nozzle, low pressure, and keep the wand moving. Older plastic can become brittle, so use cold water only and never a turbo nozzle. Test a hidden patch before you commit.

Distance, Angle and Movement: The Golden Rules

Keep the nozzle at least 30cm from the surface. For softer wood or aged plastic, increase that to 45–60cm. Angle the spray at about 45 degrees, never straight on. A direct hit drives water into joints and can gouge the surface. Keep the wand moving in a steady sweep, overlapping your passes. Do not dwell on one spot. Work from top to bottom so dirty water runs off rather than soaking back in. If you see fuzziness on wood or a change in colour, stop immediately. Also, never pressure wash cushions, fabric slings or wicker unless the manufacturer says it is safe. Wicker can unravel, and foam cushions can soak up water that never dries properly.

Preparing the Area and Protecting Surroundings

Move furniture onto grass or a tarp, not the patio, so you can see what you are doing and avoid blasting grit into nearby plants. Cover flower beds with a sheet or old curtain. Close windows and doors. Check the weather: do not pressure wash in freezing conditions, because water can freeze inside joints and crack them. Pre-soak the furniture with a garden hose to loosen dirt, and have a soft brush ready for stubborn bits. Wear eye protection and wellies. Disconnect the pressure washer when you are not using it, and never leave it running unattended. A little preparation saves a lot of repair work later.

Cleaning Wooden Furniture Without Raising the Grain

Wood is the most vulnerable material. Pressure washing can raise the grain, leaving a fuzzy surface that feels rough and looks tired. Use the lowest pressure setting you have. Better still, use a garden hose and a soft brush for most cleaning. If you must pressure wash, use a wide fan nozzle, keep at least 45cm away, and move quickly. Never hold the wand in one place. After washing, let the wood dry completely, then sand lightly with fine grit (120–180) if the grain has raised. Re-oil or seal once dry. Do not pressure wash painted wood: it will strip the paint. For painted pieces, use a gentle hose and mild soap. For weathered wood, a pressure wash can remove the grey layer, but it also softens fibres, so be cautious.

Metal and Plastic Furniture: Different Approaches

Metal furniture needs a gentle touch. Cast aluminium, steel and wrought iron can all suffer. Check for rust first. Pressure washing can force water into hollow sections, causing rust from the inside out. Use low pressure, keep 40cm away, and avoid aiming at chips or scratches. For powder-coated metal, a 25-degree nozzle is usually safe, but dry immediately with a cloth to prevent water spots. Plastic furniture, such as resin or polypropylene, is usually tougher, but it can still crack. Use low pressure and warm soapy water first. A pressure washer can lift dirt from textured surfaces, but it can also etch shiny plastic. Test a hidden area. Never use a turbo nozzle on plastic. For both metal and plastic, avoid directing spray at joints, hinges or bolts. When in doubt, turn the pressure down and use a brush.