Complete exterior cleaning guide
How to properly pressure wash different surfaces?
Maintaining a clean exterior for your home or business is crucial for both aesthetics and upkeep. In this guide, we’ll cover everything you need to know about how to pressure wash different surfaces for the best results with minimal risk.
Our goal is to provide assistance to those who wish to carry out the work themselves. At the same time, we want our guide to highlight that, no matter how simple pressure washing may seem, it requires proper knowledge to achieve good results and avoid causing damage.
Learn the benefits, expert tips, and best practices to keep your property in top shape, all while preventing damage and ensuring longevity.
We provide guidance for the pressure washing of the following surfaces. At the top of the list, you'll find the most common ones:
Block paving
(concrete or clay)
Ideal pressure
While pressure matters, what really gets the job done is the flow rate. That said, for block paving, full power at 200 bar (3000 PSI) is ideal.
Cleaning agents to avoid
There aren't any specific Cleaning agents to avoid, but using the right method is key.
Ideal distance
Keep the nozzle 250-300 mm away from the surface for the best results without causing issues.
Best tools and nozzles
- Turbo nozzle – gives a strong, rotating jet for deep cleaning.
- Flat surface cleaner – keeps the cleaning even and avoids streaks.
Risks of damage
Block paving is pretty tough, so the risk of damage is very low if done correctly.
Before and after treatment
- Before cleaning: Always wash down the surface first.
- Chemical treatment: Apply sodium hypochlorite to break down stubborn dirt, moss, and algae.
How difficult is it?
It's an easy job as long as you follow the right steps.
Other things to keep in mind
- Moss needs to go first – scrape or brush it off before applying chemicals.
- Watch out for dips – water can pool in low areas, making it harder to dry.
- Be careful with joints – don't blast water straight into the gaps between blocks, or you might wash out the sand.
Can block paving be sealed?
Yes! Sealing it after cleaning helps keep it looking fresh for longer and stops moss and dirt from coming back too quickly.
Tarmac (asphalt)
Ideal pressure
Tarmac is much softer than other surfaces, so low pressure is the way to go. Too much force can cause serious damage.
Cleaning agents to avoid
Stick to a registered biocide only. Avoid all other chemicals, as they can break down the surface.
Ideal distance
Since we're using a flat surface cleaner with a set height, distance isn't an issue - it keeps the pressure even and prevents damage.
Best tools and nozzles
- Flat surface cleaner – this is the only tool you should be using. It spreads the pressure evenly and avoids concentrated jets that could ruin the tarmac.
Risks of damage
The risk of damage is very high. Using the wrong pressure or nozzle can lead to etching, stripping, and general surface damage. Always take a careful approach.
Before and after treatment
- After washing, apply a biocide to kill off moss, algae, and other organic growth.
- Extra treatments: You might need additional steps like oil stain removal or rust removal depending on the condition of the surface.
How difficult is it?
It's a medium-difficulty job. You need to be careful with pressure, technique, and pre-existing damage.
Other things to keep in mind
- Use a figure of 8 motion with your flat surface cleaner for even cleaning.
- Check for damage before starting - repair any crumbling or broken edges first.
- Avoid direct pressure on weak spots, as tarmac can break apart under too much force.
Can tarmac be sealed?
Yes! Sealing tarmac helps even out blotchy colors, protects against oil stains, and gets rid of cement dust buildup. It also extends the life of the surface, so it's definitely worth considering.
Resin-bonded gravel
Ideal pressure
Use low pressure to avoid damaging the resin bond. Too much force can break the bond between the aggregate and loosen the stones.
Cleaning agents to avoid
You can use sodium hypochlorite (hypo) on resin, but a foaming agent is required for any chemical treatments to ensure proper application.
Ideal distance
The flat surface cleaner maintains a consistent height, so there's no need to adjust the distance manually.
Best tools and nozzles
- Flat surface cleaner – spreads pressure evenly, preventing damage.
- Fan jet nozzle – provides gentle but effective rinsing without disturbing the resin bond.
Risks of damage
The risk of damage is low, but using high pressure may weaken the bond and cause loose aggregate.
Before and after treatment
- Before cleaning: Apply sodium hypochlorite (hypo) as a pre-treatment to break down organic growth.
- After cleaning: Use a biocide to prevent future moss and algae buildup.
How difficult is it?
It's a medium-difficulty job that requires the right tools and technique to avoid damage.
Other things to keep in mind
- Use a figure of 8 motion with the flat surface cleaner for even cleaning.
- Always add a foaming agent to cleaning solutions to help them work effectively on resin surfaces.
Can resin-bonded gravel be sealed?
No, resin-bonded gravel cannot be sealed. The surface is designed to be porous, and sealing would interfere with its functionality.
Pattern imprinted concrete
Ideal pressure
Use high pressure for effective cleaning - this surface can handle it well.
Cleaning agents to avoid
No specific cleaning agents need to be avoided.
Ideal distance
Keep the nozzle 250-300mm from the surface. If using a flat surface cleaner, its set height will ensure even cleaning.
Best tools and nozzles
- Turbo nozzle – great for tackling stubborn dirt.
- Flat surface cleaner – prevents streaks and ensures even cleaning.
Risks of damage
The risk of damage is low, but be mindful of cracks and chips in the concrete.
Before and after treatment
- After washing, apply sodium hypochlorite (hypo) to kill algae and brighten the surface.
How difficult is it?
It's an easy job, as the surface is durable and can handle strong cleaning.
Other things to keep in mind
- Cracks and chips can be filled with two-pack wood filler before sealing.
- Avoid excessive pressure on damaged areas to prevent worsening cracks.
Can pattern imprinted concrete be sealed?
Yes! It can also be recoloured, helping to restore its original look.
Concrete
(plain or exposed aggregate)
Ideal pressure
Use medium pressure - too much force can etch the surface, especially on exposed aggregate.
Cleaning agents to avoid
No specific cleaning agents need to be avoided.
Ideal distance
A flat surface cleaner (FSC) is recommended, which maintains a consistent height for even cleaning.
Best tools and nozzles
- Flat surface cleaner – prevents uneven cleaning and streaks while protecting the concrete from damage.
Risks of damage
The risk of damage is medium - incorrect pressure or technique can etch the surface, leaving visible marks.
Before and after treatment
- Before cleaning, apply sodium hypochlorite (hypo) as a pre-treatment to break down dirt and organic growth.
- After cleaning, use a biocide to prevent moss and algae from returning.
How difficult is it?
It's a medium-difficulty job - care is needed to avoid over-cleaning or damaging the surface.
Other things to keep in mind
- Avoid excessive pressure on exposed aggregate, as it can loosen stones and create an uneven finish.
- Move evenly with the flat surface cleaner to prevent visible pressure marks.
Can concrete be sealed?
Yes! Sealing helps protect the surface, prevents staining, and extends its lifespan.
Permeable block paving
Same as with block paving →.
The only difference is the aggregate that is brushed into the gaps between the blocks, permeable blocks have a 3mm stone where block paved has kiln dried sand.
Cobblestones
(granite setts)
Ideal pressure
Use high pressure - granite is tough and can handle strong cleaning.
Cleaning agents to avoid
⚠️ Avoid using sodium hypochlorite (hypo) - it reacts with the metal ore in granite, which can lead to permanent rust spots. Once this happens, there's no way to reverse it.
Ideal distance
Keep the nozzle 250-300mm away from the surface to clean effectively without unnecessary wear.
Best tools and nozzles
- Turbo nozzle – provides deep cleaning for stubborn dirt.
- Flat surface cleaner (FSC) – ensures even cleaning and prevents streaking.
Risks of damage
There's no risk from pressure washing itself, but chemical damage from hypo is irreversible.
Before and after treatment
- After cleaning, apply a biocide treatment to prevent moss, algae, and organic growth from returning.
How difficult is it?
It's an easy job, as granite is a strong and durable material.
Other things to keep in mind
- Do not use hypo - it might seem like a good cleaner, but the long-term rusting effect makes it a bad choice for granite.
Can cobblestones be sealed?
Yes! Sealing helps protect the surface and enhances the natural look of the stone.
Granite slabs or countertops
Ideal pressure
Use low pressure to avoid surface damage. Granite is strong, but excessive force can cause etching.
Cleaning agents to avoid
⚠️ Do NOT use sodium hypochlorite (hypo) - it reacts with the metal ore in granite and will cause permanent rust spots that cannot be removed.
Ideal distance
Keep the nozzle 400-500mm away from the surface to prevent unnecessary wear or etching.
Best tools and nozzles
- Fan jet (60-degree spray angle) – provides gentle but effective cleaning without damaging the surface.
Risks of damage
Granite can be etched, and there is no way to reverse the damage once it occurs.
Before and after treatment
- After cleaning, apply a biocide treatment to prevent organic growth like moss and algae.
How difficult is it?
It's a medium-difficulty job due to the risk of permanent damage.
Other things to keep in mind
- Avoid using hypo at all costs - it will cause rust stains that cannot be removed.
- Hydrochloric acid can be used, but only if you are 100% sure that the material is granite and not a different type of stone.
Can granite slabs be sealed?
Yes! Sealing helps protect against stains and discoloration, keeping the surface looking its best.
Limestone paving
Ideal pressure
Use low pressure - limestone is a soft stone that can be easily damaged.
Cleaning agents to avoid
⚠️ Avoid sodium hypochlorite (hypo) and any acid-based cleaners - they will react with the stone and cause permanent damage.
Ideal distance
Keep the nozzle 400-500mm away from the surface to minimize the risk of etching.
Best tools and nozzles
- Fan jet (60-degree spray angle) – provides the gentlest cleaning method while reducing the risk of damage.
Risks of damage
Limestone can be easily etched, and once damaged, there's no way to restore its original surface.
Before and after treatment
- No specific pre- or post-treatment is recommended due to the delicate nature of limestone.
How difficult is it?
It's a difficult job, as pressure washing can easily cause permanent damage if not done with extreme care.
Other things to keep in mind
- Avoid using pressure washing if possible - limestone is too delicate, and even low pressure can cause damage.
- Use a soft wash method instead, with a suitable stone-safe cleaner and gentle rinsing.
Can limestone paving be sealed?
Yes! Sealing helps protect the stone from weathering, staining, and organic growth, making it a worthwhile investment.
Indian sandstone
Ideal pressure
Use medium pressure - Indian sandstone is durable but still requires care to prevent unnecessary wear.
Cleaning agents to avoid
Hydrochloric acid can be used, but it should be applied with caution as it may cause discoloration or damage if overused.
Ideal distance
Keep the nozzle 250-300mm from the surface for effective cleaning without causing damage.
Best tools and nozzles
- Flat surface cleaner (FSC) – provides even cleaning and prevents streaks.
- Fan jet nozzle – a gentler option for rinsing without excessive force.
- Turbo nozzle – useful for tougher areas, but avoid prolonged use on any single spot.
Risks of damage
The risk of damage is low, but using too much pressure or excessive chemical treatments can lead to surface wear or fading over time.
Before and after treatment
- For stubborn biofilms, apply sodium hypochlorite (hypo) before cleaning.
- To prolong cleanliness, a post-wash treatment with hypo can help prevent organic growth from returning.
How difficult is it?
It's an easy job, as Indian sandstone is relatively simple to clean with the right approach.
Other things to keep in mind
- If using hydrochloric acid, test a small area first to ensure it doesn't cause unwanted discoloration.
- Avoid excessive pressure in softer areas, as sandstone can vary in density.
Can Indian sandstone be sealed?
Yes! Sealing helps protect the stone from weathering, dirt buildup, and organic growth, keeping it cleaner for longer.
Porcelain slabs
Ideal pressure
Use high pressure - porcelain is a durable surface that can handle strong cleaning.
Cleaning agents to avoid
No specific cleaning agents need to be avoided.
Ideal distance
Keep the nozzle 250-300mm away from the surface for effective cleaning.
Best tools and nozzles
- Flat surface cleaner (FSC) – ensures even cleaning without streaks.
- Fan jet nozzle – a gentler option for general rinsing.
- Turbo nozzle – effective for removing tougher stains.
Risks of damage
The risk of damage is low, as porcelain is highly resistant to pressure washing.
Before and after treatment
- Sodium hypochlorite (hypo) can be used if required for stubborn stains.
- No need for biocide - porcelain is non-porous, so biocides won't penetrate or provide long-term benefits.
How difficult is it?
It's an easy job, as porcelain is one of the most resilient surfaces to clean.
Other things to keep in mind
- Porcelain doesn't absorb water, so drying times are quick, and stains are easier to remove.
- Avoid excessive use of chemicals, as they may leave residue on the surface.
Does porcelain need sealing?
Yes, you can and should seal porcelain to prevent food stains like orange juice or tomato sauce. Once sealed, cleaning is much easier.
Marble
Ideal pressure
Use medium to high pressure, but be cautious - marble is a natural stone that can be affected by aggressive cleaning methods.
Cleaning agents to avoid
⚠️ Avoid using sodium hypochlorite (hypo) or acid - both can react with marble and cause discoloration, surface degradation, or etching.
Ideal distance
Keep the nozzle 250-300mm away from the surface to clean effectively without causing damage.
Best tools and nozzles
- Flat surface cleaner (FSC) – ensures even pressure distribution and prevents streaking.
- Fan jet nozzle – a safer option for general cleaning without too much force.
- Turbo nozzle – can be used cautiously for stubborn stains but avoid prolonged use in one spot.
Risks of damage
The risk of damage is medium - marble can be etched or dulled if the wrong pressure or chemicals are used.
Before and after treatment
- A biocide can be applied if required to prevent organic growth like moss and algae.
How difficult is it?
It's an easy job, but care is needed to avoid damaging the surface.
Other things to keep in mind
- Never use acids or hypo on marble - they will cause irreversible damage.
- Use a neutral stone-safe cleaner if additional cleaning power is needed.
Can marble be sealed?
Yes! Sealing marble helps protect it from staining, weathering, and wear, keeping it looking its best for longer.
Slate
Ideal pressure
Use low pressure - slate is a delicate stone that can easily be damaged by excessive force.
Cleaning agents to avoid
⚠️ Avoid using sodium hypochlorite (hypo) or acid - both can react with the stone and cause permanent damage.
Ideal distance
Keep the nozzle 400-500mm away from the surface to reduce the risk of breaking or delaminating the slate.
Best tools and nozzles
- Fan jet (60-degree spray angle) – the safest option for gentle cleaning.
Risks of damage
The risk of damage is high - slate can easily delaminate, and sharp shards can break off if too much pressure is applied or if water hits at the wrong angle.
Before and after treatment
No specific pre- or post-treatment is recommended due to the delicate nature of slate.
How difficult is it?
It's a challenging job due to the risk of surface damage from pressure washing.
Other things to keep in mind
- Avoid high pressure and direct angles - water can get under layers of slate and cause them to break apart.
- Use a soft washing method if possible, with a gentle stone-safe cleaner and minimal pressure.
Can slate be sealed?
Yes! Sealing slate helps protect it from weathering, water absorption, and staining, making it a great option for long-term protection.
Polished or honed stone
Ideal pressure
Use low pressure - this type of stone is delicate and can be easily damaged.
Cleaning agents to avoid
⚠️ Never use hydrochloric acid - it will react with the stone and cause permanent damage.
Ideal distance
Keep the nozzle 400-500mm away from the surface to prevent etching or surface wear.
Best tools and nozzles
- Fan jet (60-degree spray angle) – provides gentle, even cleaning while minimizing the risk of surface damage.
Risks of damage
The risk of damage is medium - polished or honed stone is very porous, and improper cleaning can cause staining or surface wear.
Before and after treatment
- Biocide treatment is essential - it's the only way to address deep-seated biofilm stains.
How difficult is it?
It's a difficult job, especially if the stone wasn't sealed when installed.
Other things to keep in mind
- Polished and honed stone is extremely porous - any biofilm will sink into the stone, making cleaning very challenging.
- Even after cleaning, embedded biofilm stains may remain visible - they won't disappear immediately.
- Biocide treatment is the only effective solution, but it takes months to fully work as it slowly breaks down deep-set stains.
Can polished or honed stone be sealed?
Yes! Sealing is crucial - if the stone wasn't sealed when installed, it will be much harder to clean in the future. Sealing prevents biofilm from penetrating deep into the surface.
Stone mastic asphalt (SMA)
Wood decking
Ideal pressure
Use low pressure - wood is delicate and can be easily damaged by excessive force.
Cleaning agents to avoid
⚠️ Avoid using sodium hypochlorite (hypo) - it breaks down the melanin in the wood, causing it to weaken and fail over time.
Ideal distance
Keep the nozzle 250-300mm away from the surface to avoid damaging the wood fibers.
Best tools and nozzles
- Fan jet nozzle – provides gentle, even cleaning while minimizing the risk of gouging or damage.
Risks of damage
The risk of damage is high - too much pressure or incorrect technique can leave permanent streaks, splintering, or even structural weakening.
Before and after treatment
- After washing, use a specialist wood cleaner to nourish the surface.
- Once dry, apply a high-quality wood oil to restore and protect the decking.
How difficult is it?
It's a difficult job, as incorrect pressure or technique can cause irreversible damage.
Other things to keep in mind
- Trigger technique matters: Never pull the trigger while pointing at the wood. Instead:
- Point away, pull the trigger.
- Lower the lance and start moving along the full length of the deck.
- Release the trigger away from the wood to avoid leaving harsh stop/start marks.
- Move continuously - stopping mid-pass will leave permanent lines in the wood.
Can wood decking be sealed?
Yes! Sealing with a good quality wood oil helps protect against weathering, moisture damage, and UV exposure.