Should You Jet Wash Bricks? 🧱💦
Jet washing (also called pressure washing) is often the first method homeowners consider when bricks begin to look tired, stained, or moss-covered. At first glance, blasting away grime seems like a fast and effective solution. However, brickwork is more delicate than many assume, and improper washing can cause irreversible damage.
This guide explores when jet washing is safe, when it’s risky, what alternatives exist, and how costs, pressures, and risks compare. It combines practical experience, building-science considerations, and common issues found in UK homes.
1. How Jet Washing Affects Bricks
Bricks vary widely: some are dense and durable, while others are soft, sand-faced, handmade, or already weathered by decades of British rain and frost. When a high-pressure jet is applied, the following can occur:
Potential Positive Effects
- Removes algae, moss, soot, and dirt quickly
- Restores a fresh, clean appearance
- Improves kerb appeal before selling a property
- Helps reveal underlying defects that were hidden by dirt
Potential Negative Effects
Sadly, the negative effects can outweigh the positives in many cases:
- Erosion of the brick surface — the jet strips away the protective fired face
- Mortar damage — mortar joints break apart, leading to draughts and damp
- Increased water absorption — because the protective surfaces are worn away
- Spalling — moisture enters the brick, freezes in winter, and causes chunks to fall off
- Colour fading or patchiness
- Increased long-term maintenance costs
2. Understanding Brick Strength and Jet Washer Pressure
Not all bricks tolerate pressure the same way, and not all jet washers operate at gentle levels.
Typical Jet Washer Pressure Levels
| Pressure (psi) | Pressure (bar approx.) | Suitable Uses | Risk to Bricks |
|---|---|---|---|
| 500–1000 psi | 35–70 bar | Car cleaning, light patio rinse | Low–moderate |
| 1000–2000 psi | 70–140 bar | Patio slabs, fencing, decking | Moderate |
| 2000–3000 psi | 140–200 bar | Heavy concrete cleaning | High |
| 3000+ psi | 200+ bar | Industrial surfaces only | Very high |
Most consumer jet washers in the UK fall between 1200–2000 psi, which is far higher than recommended for many traditional brick types.
Brick Types and Sensitivity
| Brick Type | Characteristics | Jet Washing Safety |
|---|---|---|
| Engineering bricks | Very dense, low porosity | Safer if pressure kept low |
| Modern wire-cut bricks | Relatively durable | Moderate risk |
| Handmade / reclaimed bricks | Soft, porous | Generally unsafe |
| Sand-faced bricks | Weak surface texture | High risk of surface loss |
| Victorian solid bricks | Often weathered | Unsafe unless extremely gentle |
3. When Jet Washing Bricks Is Not Recommended
Jet washing is usually unsuitable if any of the following apply:
⚠️ 1. The brick face is flaking or crumbling
A jet washer accelerates deterioration dramatically.
⚠️ 2. Mortar joints are eroded or lime-based
Old lime mortar is softer than modern cement-based mortar. Jet washing can remove it entirely.
⚠️ 3. The wall is already affected by damp or water ingress
Jet washing forces water deep into the brickwork, making damp worse.
⚠️ 4. The bricks are historic or handmade
Anything pre-1920s tends to be softer and more breathable.
⚠️ 5. There are previously applied paint coatings or waterproof sealants
These may lift unevenly when blasted, creating a patchy appearance.
4. When Jet Washing May Be Acceptable
There are cases where jet washing can be used cautiously:
✔️ 1. Dense engineering bricks
These are more pressure-resistant.
✔️ 2. Lower pressure and wider nozzle fan
A 40–60-degree fan angle spreads the force.
✔️ 3. Standing at a safe distance (0.5–1 metre)
The closer the nozzle, the stronger the impact.
✔️ 4. Using a low-flow, low-pressure setting (below 1000 psi)
This is still strong enough to clean algae but gentle enough to reduce damage risk.
✔️ 5. Cleaning only surface dirt or organic growth
Deep staining may require other methods, so don’t keep increasing pressure to compensate.
5. The Hidden Costs of Jet Washing Brickwork
Jet washing looks affordable at first glance, but it can create expensive problems.
Short-Term Savings
| Task | Typical Cost (£) |
|---|---|
| Hiring a domestic jet washer (per day) | £25–£40 |
| Hiring a high-end washer | £45–£70 |
| Buying a domestic jet washer | £60–£300 |
These low initial costs tempt many homeowners.
Potential Long-Term Costs
| Damage Caused | Potential Repair Cost (£) |
|---|---|
| Repointing damaged mortar | £20–£50 per m² |
| Replacing spalled bricks | £15–£35 per brick including labour |
| Treating damp problems | £150–£800+ |
| Rebuilding a damaged section of wall | £500–£3,000+ |
A simple £30 jet washing session can unexpectedly turn into a £1,000 repair bill down the line.
6. What Happens When Water Gets Forced Into Bricks?
Brick is naturally porous, but it is designed to “breathe,” releasing moisture gently over time. High-pressure washing disrupts this balance.
Consequences of high-pressure water intrusion:
- Moisture trapped behind internal plaster
- Efflorescence (white salt deposits)
- Freeze-thaw damage in winter
- Reduced insulation performance
- Mould growth internally
This is why many conservation specialists strongly advise against jet washing older brick buildings.
7. Safe Alternatives to Jet Washing Bricks
Fortunately, safer cleaning methods exist. These techniques avoid the forceful stripping action of a jet washer.
1. Softwashing 🫧
A gentle, low-pressure application of biodegradable cleaning solution followed by a rinse.
- Effective on algae, moss, organic staining
- Minimal risk to bricks
- Commonly used in conservation work
2. Steam Cleaning 🌫️
Using superheated water at very low pressure.
- Excellent for dirt, pollution, algae
- Safe for most brick types
- Leaves no chemical residues
3. Hand Scrubbing with a Masonry Cleaner
A stiff brush (not wire) paired with a mild cleaning agent.
- Laborious but safe
- Good for small areas
4. Nebulous Spraying
Often used on historic buildings.
- Applies a fine mist to loosen dirt without mechanical force
- Suitable for delicate or very aged bricks
5. Non-abrasive biocide treatments
Great for algae and moss overgrowth.
- Results appear over several days
- Gentle and predictable
8. Comparison Table: Jet Washing vs Alternatives
| Method | Pressure Level | Risk to Bricks | Typical Cost Range in UK (£) | Best Use Case |
|---|---|---|---|---|
| Jet washing | High | High | £25–£70 | Robust, modern bricks |
| Softwash | Low | Low | £70–£200 (small area) | Organic growth |
| Steam cleaning | Low | Very low | £100–£300 | Pollution, grime |
| Hand scrubbing | Minimal | Very low | £10–£40 | Small sections |
| Nebulous spray | Very low | Very low | £150–£500 | Historic buildings |
9. Common Jet Washing Mistakes
Even when people try to be careful, these errors often cause damage:
❌ Using a turbo or rotary nozzle
These concentrate pressure and chisel the brick surface.
❌ Holding the nozzle close to the wall
Impact is exponentially stronger at short distances.
❌ Using chemicals not meant for masonry
Some household cleaners react with brick minerals.
❌ Cleaning during freezing conditions
Water left on bricks can freeze and expand.
❌ Trying to remove stubborn stains with more pressure
Oil, soot, and iron staining often need chemical or steam solutions—not force.
10. How Professionals Assess Whether Jet Washing Is Safe
A specialist would typically consider:
- Brick age and type
- Mortar composition (lime vs cement)
- Existing cracks or spalling
- Exposure (north-facing walls stay wetter)
- Wall function (structural vs decorative)
- Any previous repairs or sealants
- Presence of cavity vs solid walls
Based on this assessment, they may refuse jet washing and offer a safer method instead.
11. Tips If You Still Decide to Jet Wash
If you ultimately choose to proceed, follow these safer-practice guidelines:
🟢 Use the lowest pressure possible
Preferably under 1000 psi.
🟢 Stand at least 1 metre away
Distance reduces risk dramatically.
🟢 Use a wide spray angle
40–60 degrees is safer than narrow angles.
🟢 Test in a hidden patch
Check for surface erosion or colour change.
🟢 Avoid pointing upwards into brickwork
This forces water behind the wall.
🟢 Never wash soft, handmade, or historic bricks
Too risky.
🟢 Rinse thoroughly
Leaving detergent residues can discolour brickwork.
12. Myths About Jet Washing Bricks
Many homeowners hear the same misconceptions:
Myth 1: “Bricks are tough, they can take it.”
Many bricks—especially those in UK Victorian homes—are intentionally soft and breathable.
Myth 2: “Damage only occurs if the pressure is extremely high.”
Even low pressures can remove the brick face if the bricks are weathered.
Myth 3: “Jet washing is the only way to make bricks look new.”
Steam cleaning can look better and is gentler.
Myth 4: “Sealing the bricks afterwards fixes everything.”
Many sealants trap moisture, causing more damage long-term.
13. Example Scenarios
Here are realistic situations and whether jet washing is suitable:
Scenario A: 1980s house with dense engineering bricks
- Bricks are durable
- Mortar generally cement-based
- Limited weathering
Verdict: Possible with caution and low pressure.
Scenario B: 1900 Victorian terrace with soft red bricks
- Likely lime mortar
- Weathered and porous
Verdict: Avoid jet washing. Use steam or softwash instead.
Scenario C: Garden wall built with cheap modern bricks
- Mixed durability
- Often hollow or lightly fired
Verdict: Better to avoid pressure washing.
Scenario D: Soot-stained chimney stack
- High exposure to moisture
- Often historic brick
Verdict: Never jet wash. Use steam cleaning.
14. Environmental Considerations 🌿
Jet washing uses more water than softwashing or steam cleaning. It also risks dislodging mortar and bricks, which contributes to debris entering drains.
Environmental positives of alternatives:
- Lower water use
- No aggressive mechanical force
- Biodegradable cleansers available
15. Should You Jet Wash Bricks? Final Assessment
Putting everything together:
In most cases, the answer is: no — it’s not advisable.
Brickwork is too varied and too easily damaged by high pressure. While it can occasionally be safe on the hardest bricks at the lowest pressures, the risk often outweighs the reward.
A cleaner wall is nice, but a damaged one can cost hundreds or thousands of pounds to fix. Safer alternatives like softwashing or steam cleaning provide excellent results without risking your brickwork.
16. Summary Table
| Question | Short Answer | Notes |
|---|---|---|
| Is jet washing bricks generally safe? | ❌ No | Too much risk of erosion and moisture damage |
| Are some bricks safe to wash? | ✔️ Yes, but limited | Engineering bricks only, low pressure |
| What are the safest methods? | 🟢 Steam or softwash | Minimal structural impact |
| Can jet washing cause expensive damage? | ✔️ Yes | Repairs can exceed £1,000 |
| Should historic bricks be washed? | ❌ Never | Use specialist low-pressure methods |
17. Seasonal Factors That Affect Brick Cleaning
The time of year dramatically influences whether jet washing is safe or risky.
Spring
- Ideal for gentle cleaning
- Bricks dry faster
- Lower chance of freezing damage
Summer
- Quick drying time
- Risk of chemical cleaners evaporating too quickly
- High-pressure washing can cause rapid surface drying, potentially leading to hairline cracks in already weak bricks
Autumn
- Bricks begin to stay damp longer
- Any water forced inside takes longer to escape
- Moss growth increases, tempting more frequent cleaning
Winter
- Worst time for jet washing
- Water freezes inside brick pores
- Freeze–thaw cycles lead to spalling and structural damage
👉 Takeaway: The colder and wetter the season, the more dangerous jet washing becomes.
18. How Brick Age Influences Cleaning Choices
An older wall tells a story through wear, weathering, and repairs. These characteristics directly affect how it should be cleaned.
Older Brickwork (pre-1920)
- Typically soft, handmade, highly porous
- Often paired with lime mortar
- Should avoid high-pressure methods completely
Mid-Century Brickwork (1930s–1970s)
- More durable than Victorian brick
- Still may show weathering or mortar weakness
- Low-pressure or steam preferred
Modern Brickwork (1980s–present)
- Machine-made, denser bricks
- Often safe for low-pressure cleaning
- Mortar still vulnerable if jetting too close
👉 Conclusion: Age matters just as much as brick type when deciding whether jet washing is safe.
19. Colour Changes After Jet Washing
A surprising side effect of jet washing is the alteration in brick colour. While some expect brighter brickwork, the opposite can happen.
Causes of Colour Shift:
- Removal of the outer fired layer exposes lighter or duller material
- Uneven cleaning leaves patchy tones
- If moisture enters the brick, dark damp patches can linger for days or weeks
- Moss removal can leave ghost marks where roots penetrated the surface
Permanent vs Temporary Changes
| Colour Change Type | Likely Permanent? | Notes |
|---|---|---|
| Patchy surface erosion | Yes | Caused by abrasive force |
| Damp staining | No | Disappears once bricks dry |
| Loss of protective face | Yes | Brick becomes rougher and lighter |
| Moss ghosting | Sometimes | Roots leave imprints |
👉 If uniform colour is important, jet washing can be disappointing.
20. Impact on Adjacent Surfaces
Jet washing doesn’t just affect the brick itself — nearby features can also suffer unintended damage.
Timber Elements
Fascias, soffits, sheds, and garden fencing can be shredded by high pressure.
Pointing & Lead Flashing
Mortar can be blown out and lead flashing can be lifted or bent.
Windows & Door Frames
Old seals or putty glazing can break, causing drafts and water ingress.
Landscaping
Jetting can dislodge stones, gravel, or soil around paths and flower beds.
Outdoor electrics
Sockets, lights, and wiring housings may not withstand forced water spray.
👉 A “quick clean” can accidentally damage more than just the brickwork.
21. Long-Term Maintenance After Cleaning
Whatever method is chosen, maintaining brickwork properly helps ensure a long lifespan.
Post-Cleaning Checks
- Inspect mortar joints for new erosion
- Look for signs of spalling developing in the days after cleaning
- Monitor internal walls for damp patches
- Check any painted sections for lifting or cracks
Maintenance Tips
- Use biocide treatments annually to reduce moss regrowth
- Keep nearby plants trimmed to improve airflow
- Avoid constantly wetting the base of walls with hoses or leaky gutters
- Repoint when mortar begins to crumble — especially lime mortar
Cost Considerations (£)
| Maintenance Task | Typical UK Cost |
|---|---|
| Biocide treatment (small area) | £40–£100 |
| Lime repointing | £25–£60 per m² |
| Brick replacements | £15–£35 per brick |
| Gutter repair to reduce wall damp | £50–£150 |
👉 Brick maintenance is ongoing, but less costly than repairing damage caused by high-pressure cleaning.