Dirty or stained concrete surfaces are common across Newcastle due to rain, dust, and foot traffic. Driveways, paths, and slabs can develop algae, mould, and oil stains that make the surface unsafe or unattractive. Many people either ignore it or try methods that don’t work.
Using the wrong approach—like high pressure too close to the surface, or harsh chemicals—often causes damage. Homeowners may also waste time without knowing whether the area needs detergent, sealing, or just rinsing.
This guide explains how to clean concrete the right way using a pressure washer. It walks through safety, prep, tools, technique, and post-cleaning care. Whether you’re doing it for the first time or maintaining a driveway before sealing, this covers what matters.
What Pressure Washing Actually Does
Pressure washing uses water pushed at high force to clear concrete surfaces of dirt, oil, grime, and algae. It’s not just cosmetic. In Newcastle’s damp climate, moss and mildew can make paths and slabs slippery. Cleaning them improves both appearance and safety.
Water pressure enters the small pores in concrete, pushing out particles that brushing alone can’t remove. When used correctly, it can clean concrete without harming the surface.
This process is often used before applying sealers or resurfacing layers. It also helps check for cracks, scale, or spalling that may need attention later.
When It’s Worth Doing Yourself
Pressure washing is effective for many concrete areas and can be done without professional help if the surface is in good condition.
- Driveways with surface dirt or oil
- Pool surrounds with algae buildup
- Footpaths and patios with leaf stains
- Slabs before resealing or repainting
If the slab is level, sealed correctly, and doesn’t show signs of cracking or scaling, DIY cleaning is usually enough. Just make sure to check for loose concrete, lifting corners, or old paint—these may need more than surface cleaning.
DIY saves money but requires attention to detail. Sloppy work causes streaks, damage, or missed spots that look worse after drying.
What Gear You’ll Need and Why It Matters
Choosing the right gear matters more than pressure level. Too much force or the wrong nozzle will damage the concrete surface. Most home-grade washers range from 2000–3000 PSI, which is enough for cleaning if used correctly.
- Pressure washer (2000–3000 PSI range)
- 25-degree nozzle for coverage
- 15-degree nozzle for tough spots
- Concrete-safe detergent
- Nitrile gloves and safety glasses
- Non-slip footwear
Lower pressure won’t clean deep stains. Higher pressure risks leaving surface marks or striping. Proper nozzles and safety gear help control the result without causing surface damage.
Steps to Prepare the Surface
Proper preparation makes cleaning faster and avoids damage. Rushing this step is one of the most common DIY mistakes.
- Sweep away loose dirt or leaves
- Check for cracks, lifted edges, or weak spots
- Repair major faults before applying pressure
- Move furniture, bins, and potted plants
- Apply detergent to heavy stains and let it sit 10–15 minutes
Preparation gives the pressure washer a clean base and helps detergent break down oils. If moss or mould is present, soft brushing before spraying will improve the final result.
Washing Technique That Works
Hold the nozzle about 30 cm from the surface. Move in overlapping straight lines, keeping pressure consistent. Never hold the spray in one place—it can wear down the surface and leave a visible dip or line.
Start with a 25-degree nozzle and switch to a narrower one only if dirt remains. If detergent was applied, wash from the highest point downward to avoid streaks. Use side-to-side motion and avoid circles or tight swirls.
Keep the spray head moving. Even slow passes prevent uneven cleaning. After rinsing, give it time to dry before judging the finish.
Aftercare and Surface Protection
After cleaning, let the area dry completely—usually several hours depending on sun and airflow. Walking on wet concrete won’t cause harm, but sealing or repainting must only happen when the surface is fully dry.
For better results, consider sealing the slab. Sealing helps prevent future buildup and makes cleaning easier next time.
Sweep or rinse every few weeks to stop dirt from collecting. Avoid using fertiliser or chemical products near clean concrete to prevent staining.
Mistakes to Avoid
Pressure washing looks easy but can go wrong quickly. The most common mistakes happen when people treat all slabs the same or use too much force.
- Spraying too close or using the wrong nozzle
- Skipping detergent and expecting water to clean oil
- Cleaning sealed or coloured concrete without testing
- Using cheap gear without safety features
- Not checking for cracks before washing
These mistakes cause etching, uneven results, and surface damage. Testing a small corner first is always worth the time.
When a Professional Is the Better Option
Not every slab is worth DIY effort. Some conditions make hiring a professional more efficient, especially when equipment rental or repairs add to the cost.
- Large driveways or multilevel slabs
- Spalling or scaling that needs prep first
- Heavily stained commercial zones
- Time-sensitive cleaning before sealing or sale
- No access to pressure washing gear
Professionals also use surface cleaners, water recovery systems, and stronger detergents approved for concrete. This gives more even results with less mess.
FAQs
Is pressure washing safe for all types of concrete?
Yes, if done right. Avoid high pressure on stamped, coloured, or sealed slabs. Always test a small spot first.
How often should I pressure wash my driveway?
Once or twice a year works for most homes in Newcastle. More if shaded or near trees.
Do I need detergent?
For oil, mould, or dark buildup, yes. Water alone won’t clear embedded stains.
Can I reseal the surface after cleaning?
Yes, and it’s recommended for driveways or surrounds. Wait until the slab is fully dry.
What PSI is best for home use?
Between 2000–3000 PSI is ideal. More than 3000 risks of damage if not handled carefully.
Let Con Ops Handle It
If your concrete looks worn, slippery, or stained, we’ll bring it back to life. Con Ops provides pressure washing across Newcastle, Lake Macquarie, and Maitland—plus sealing, resurfacing, and repair if needed.
Share a photo and describe the surface. We’ll recommend the right approach—no pressure, no upselling.