What Is the Best Way to Clean Brick?
Brick is durable, beautiful, and timeless — but it also attracts dirt, algae, staining and general weathering over time. Whether you’re cleaning a brick wall, patio, façade, chimney, or feature wall inside your home, the best cleaning method depends entirely on the brick’s condition, age, and the type of dirt or staining present.
This guide covers the safest and most effective ways to clean brick, including comparisons of cleaning methods, tools, materials, cost breakdowns, timelines, safety tips, and avoidable mistakes.
Understanding Brick and Why It Gets Dirty
Brick is porous — meaning it absorbs moisture, collects grime, and can hold onto biological growth such as moss and algae. Typical causes of brick discolouration include:
- Dirt & airborne pollution
- Algae, moss, mildew, lichen
- Efflorescence (white crystalline salts)
- Rust staining
- Paint or mortar smears
- Soot (especially chimneys)
- Water run-off staining
- General weathering over decades
Because brick varies in hardness, porosity, age, and previous treatments, the cleaning approach must always match the brick type. Using the wrong method can permanently damage the surface.
The Best Way to Clean Brick (Short Answer)
The safest all-purpose method is:
Low-pressure cleaning using mild detergent (dish soap or brick-safe detergent) and soft brushing, followed by a gentle rinse.
This works for most general grime and weathering.
BUT — depending on the staining type, other specialised methods may be better, such as:
- Wet cleaning (low-pressure water) for dirt, grime, algae
- Steam cleaning for delicate or older bricks
- Poultice cleaning for oil or deep stains
- Acid cleaning (only when appropriate) for mortar smears
- Biocidal cleaning for long-term algae prevention
- Efflorescence brushing for salt removal
Let’s break these down.
Comparison of Brick Cleaning Methods
Table 1: Overview of Common Brick Cleaning Methods
| Cleaning Method | Best For | Risk Level | Typical Cost (DIY) | Notes |
|---|---|---|---|---|
| Low-Pressure Water + Detergent | Dirt, grime, algae | Low | £5–£20 | Safest and cheapest option |
| Steam Cleaning | Historic or delicate brick | Very Low | £50–£150 (machine hire) | No chemicals needed |
| Biocide Treatment | Moss, algae, lichen | Low–Medium | £15–£50 | Works over weeks, prevents regrowth |
| Poultice Cleaning | Oil, rust, deep stains | Low–Medium | £10–£30 | Draws stain out of brick |
| Acid Cleaning (e.g., brick acid) | Mortar smears, heavy staining | High | £10–£25 | Must be diluted; can etch brick |
| Pressure Washing (very low PSI) | Heavily soiled exterior brick | Medium–High | £40–£70 (machine hire) | Must be used carefully; too strong can destroy brick |
| Dry Brushing | Efflorescence | Very Low | £2–£5 | Best for salt deposits |
Most Recommended General Cleaning Method
✅ Method: Low-Pressure Water + Mild Detergent
This is the safest, most universal brick-cleaning technique.
Why it works well
- Removes dirt, surface grime, algae, pollution residue
- Safe for most brick types
- Minimal cost
- No damage to mortar
- Suitable indoors and outdoors
Tools and Materials
- Bucket
- Warm water
- Mild detergent (e.g., washing-up liquid or brick-safe cleaner)
- Soft-bristle brush
- Garden hose with low-pressure nozzle
- Protective gloves
Step-by-Step Instructions
- Wet the brick surface with low-pressure water.
- Mix detergent solution:
- Warm water + a few drops of mild detergent
- Apply solution generously to the brick.
- Gently scrub using circular motions.
- Let it sit for 5–10 minutes.
- Rinse thoroughly with low-pressure clean water.
- Repeat if needed for stubborn patches.
Cost Estimate
| Item | Estimated Cost |
|---|---|
| Detergent | £1–£3 |
| Brush | £2–£10 |
| Water cost | < £1 |
| Total DIY cost | £3–£14 |
Specialised Brick Cleaning Methods
1. Steam Cleaning (Safe for Older or Fragile Brick)
Steam is excellent for heritage buildings or soft, hand-made brick that could crumble under harsher cleaning.
Pros
- No chemicals
- Low risk of damage
- Kills algae and bacteria
- Good for interior brick
Cons
- Requires hire of a steam machine
- Slower than other methods
Ideal For
- Victorian or Georgian brick
- Painted-over brick (softens paint)
- Chimneys
- Soot and smoke stains
2. Biocide Cleaning (For Moss, Algae & Lichen)
If your brick is green, slimy, or speckled with lichen, a biocidal wash is often the best long-term solution.
Why it’s effective
Biocides kill organic growth and prevent regrowth for months or even years.
Steps
- Apply biocide to dry brick.
- Leave for 24–48 hours.
- Rains or rinsing remove the residue.
Cost
£15–£50 depending on product size.
Caution
Avoid contact with plants; protect grass and flowerbeds.
3. Efflorescence Removal (Salt Staining)
Efflorescence = white powdery salt residue on bricks.
This happens when water evaporates and leaves salts behind.
Best Method: DRY BRUSHING
Never wet efflorescence — it returns worse.
Steps
- Use a stiff dry brush.
- Brush salts off the surface.
- Vacuum if indoors.
- Improve drainage or apply water repellent if problem persists.
Cost
£2–£5 (brush only)
4. Poultice Cleaning (Oil, Grease, Rust Stains)
Poultices draw deep stains out of porous materials like brick.
How it works
A paste mixture is applied, left to dry, then peeled/scraped off — pulling the contaminants with it.
Ingredients (example)
- Baking soda
- Water or hydrogen peroxide
- Absorbent material (clay or cat litter for oil)
Cost
£5–£15 depending on materials.
5. Acid Cleaning (Use with Extreme Caution)
Acid cleaning is powerful but dangerous to brick.
It can remove mortar smears, heavy rust stains, and stubborn marks — but must always be diluted, used carefully, and tested first.
Never use acid for:
- Old, soft, or historic brick
- Painted brick
- Interiors
- Brick with damaged mortar
- Brick less than one year old
When it can be used
- Hard, modern engineering brick
- Removing mortar smears after repointing
- Tackling tough mineral stains
Typical Rule
Always follow dilution instructions (often 1:10 or weaker).
Cost
£10–£25 per bottle.
6. Pressure Washing (Only Low PSI)
Pressure washing brick can be safe only under very controlled conditions.
Use guidelines:
- Max 500–800 PSI on brick
- Fan nozzle (never pinpoint jet)
- Maintain safe distance (2–3 feet)
- Do not blast mortar joints
- Pre-wet brick before washing
Risks:
- Etching brick face
- Blowing out mortar
- Water ingress
- Permanent damage
Cost
£40–£70 for hire of a pressure washer.
Table 2: Matching the Cleaning Method to the Problem
| Problem / Stain Type | Best Cleaning Method | Second Option | Avoid |
|---|---|---|---|
| Dirt & general grime | Mild detergent & soft brush | Steam cleaning | High-pressure washing |
| Moss, algae, lichen | Biocide treatment | Detergent + scrubbing | Acid cleaning |
| Efflorescence | Dry brushing | Vacuuming | Water |
| Mortar smears | Acid clean (carefully) | Steam | Strong scrubbing on new mortar |
| Oil or grease | Poultice | Detergent & hot water | Pressure washing |
| Soot or smoke staining | Steam | Detergent | Acid |
| Rust stains | Poultice with peroxide | Mild acid (carefully) | Brute scrubbing |
| Paint removal | Steam | Chemical stripper | Abrasive sanding |
Step-by-Step Full Brick Cleaning Process (Complete Guide)
Whether you’re cleaning exterior walls, a patio, an interior fireplace, or old brickwork, follow this structured cleaning plan.
1. Inspect the Brick
Look for:
- Loose or crumbling mortar
- Spalling (brick flaking or shedding)
- Deep cracks
- Salt deposits
- Biological growth
If the brick is fragile, choose the gentlest method (steam or hand washing).
2. Pre-Soak the Brick (Most Methods)
Wetting the brick first helps:
- Prevent detergent absorption
- Reduce streaking
- Make grime easier to lift
⚠️ Exception: Do not pre-wet if dealing with efflorescence or poultice cleaning.
3. Apply Your Cleaning Solution
Depending on the selected method, apply:
- Detergent
- Biocide
- Steam
- Poultice
- Diluted acid (rarely)
Let it dwell for the recommended time.
4. Agitate or Scrub if Required
Use:
- Soft brush for general dirt
- Medium brush for algae
- NO wire brushes (they scratch brick)
5. Rinse Thoroughly
A garden hose is ideal.
Indoor brick can be rinsed using a bucket and sponge.
6. Let It Dry
Brick can look patchy while drying — this is normal.
Drying time:
- Exterior: 12–48 hours
- Interior: 24–72 hours
How Much Does Brick Cleaning Cost in the UK?
Table 3: DIY Cost Breakdown
| Cleaning Approach | Estimated DIY Cost |
|---|---|
| Mild detergent & brush | £3–£14 |
| Biocide treatment | £15–£50 |
| Steam machine hire | £50–£150 |
| Pressure washer hire | £40–£70 |
| Poultice materials | £5–£15 |
| Acid cleaner | £10–£25 |
Most homeowners spend £10–£30 on a simple DIY cleaning session.
Safety Tips for Cleaning Brick
🧱💧 Safety is crucial.
Avoid Common Mistakes
- Don’t use wire brushes → They permanently scratch brick.
- Avoid excessive pressure washing → Can blow out mortar.
- Never mix bleach with acid → Toxic fumes.
- Test cleaners on a small area first.
- Protect nearby plants when using chemicals.
- Wear safety gear: gloves, goggles, mask.
Common Brick Cleaning Mistakes to Avoid
❌ Using high-pressure washing
Bricks and mortar are softer than you think. High pressure can strip the surface layer.
❌ Applying acid without dilution
This can permanently etch the brick face.
❌ Cleaning on a hot sunny day
Causes cleaners to dry too fast and leave streaks.
❌ Not rinsing thoroughly
Detergent left behind attracts dirt faster.
❌ Applying chemicals on very old brick
Older bricks are often handmade and fragile.
Which Method Lasts the Longest?
| Method | Immediate Cleaning Power | Long-Term Results | Notes |
|---|---|---|---|
| Detergent wash | Moderate | Moderate | Needs periodic repeating |
| Biocide | High | High | Prevents regrowth for 12–36 months |
| Steam | Good | Moderate | Eco-friendly |
| Acid | Very high | High | Should only be used once per issue |
| Poultice | Targeted | High | Works for specific stains |
| Low pressure washing | Good | Moderate | Must be gentle |
For longest cleanliness on exterior brick:
Biocide + gentle wash is the most durable combo.
Best Way to Clean Interior Brick
Interior brick is usually more fragile and sensitive to chemicals.
Best method:
- Vacuum loose dust
- Warm water + mild detergent
- Soft brush
- Sponge rinse
Avoid:
- Pressure washing
- Acid cleaners
- Harsh scrubbing
For soot-stained fireplace brick, steam cleaning is extremely effective.
Best Way to Clean Exterior Brick Walls
For moss, algae, dirt, or road pollution:
- Wet wall
- Apply detergent or biocide
- Soft brush scrubbing
- Low-pressure hose rinse
For heavily contaminated walls:
- Steam cleaning is safer than heavy pressure washing.
How Often Should You Clean Brick?
Frequency depends on exposure:
| Environment | Cleaning Frequency |
|---|---|
| Shaded/damp garden areas | Every 12–18 months |
| Roadside exterior walls | Every 1–2 years |
| Sunny, dry walls | Every 2–3 years |
| Interior brick | Every 3–5 years or as needed |
Can You Damage Brick by Cleaning It?
Absolutely — brick is strong but not invincible.
Risks include:
- Etching from acid
- Mortar loss from pressure washing
- Water penetration
- Colour fading
- Surface damage from wire brushes
Always start with the gentlest method first.
Conclusion: What Is the Best Way to Clean Brick?
The best universal method to clean most brick surfaces is:
Low-pressure water + mild detergent + soft-bristle scrubbing + gentle rinse.
It is inexpensive, safe, and effective for the majority of cleaning needs.
For specific issues, choose the right method:
- Algae/moss → Biocide
- Efflorescence → Dry brushing
- Deep stains → Poultice
- Mortar smears → Diluted acid (caution!)
- Historic brick → Steam
By matching the method to the stain and the brick type, you can keep your brickwork clean, protected, and looking its best for many years to come.
Preventing Damage to Brick After Cleaning
Once brick has been cleaned, it’s important to protect it so you don’t have to repeat the process too often. After the brick is fully dry, many homeowners choose to apply a breathable water repellent. Unlike sealers that trap moisture, breathable protectants allow the brick to release water vapour while reducing absorption of rain and dirt. This helps minimise moss growth, staining, and frost damage. Any product used should specifically state that it is suitable for brick. Avoid heavy, glossy sealers as these can cause long-term deterioration by trapping moisture within the masonry.
Climate Considerations
Different climates influence how quickly brick gets dirty and how often you’ll need to clean it. In damp and shaded gardens, algae tends to appear faster due to moisture retention. In coastal areas, salt deposits may show up more frequently, requiring periodic dry brushing. Urban areas often suffer from pollution staining, meaning exterior brick might need more frequent gentle washing. Understanding your local environment helps you choose the right maintenance schedule and cleaning method.
Eco-Friendly Brick Cleaning Options
For homeowners wanting a greener approach, several eco-friendly cleaning methods work well. Steam cleaning is one of the best options since it uses no chemicals and minimal water. Another method is scrubbing with warm water and plant-based detergents, which are biodegradable and mild on brick. Natural poultices, made from baking soda or clay, are effective for specific stains without harsh chemicals. Choosing eco-friendly options also reduces risk to garden plants, pets, and surrounding soil.
Seasonal Maintenance Tips
Maintaining brickwork seasonally keeps small issues from becoming big problems. In autumn, remove fallen leaves and organic debris from brick patios to prevent staining. In winter, check for frost damage and avoid using de-icing salts near brick, as they contribute to efflorescence. Spring is ideal for gentle cleaning since temperatures are mild and moisture evaporates evenly. In summer, avoid cleaning in direct sunlight because cleaning solutions dry too fast and may streak.
When Brick Should Not Be Cleaned
Certain situations require postponing cleaning to protect the masonry. Avoid cleaning brick when temperatures are below freezing, as water can enter pores and freeze, causing cracks. Newly built brickwork should not be acid cleaned until the mortar is fully cured, typically around 30 days. Also avoid harsh cleaning techniques on bricks that are already spalling, cracking, or have severely deteriorated mortar. In these cases, repairs or repointing should take priority before any cleaning is attempted.