Mould on house siding is not only unsightly but can also pose serious health risks and damage your home’s exterior over time. Whether you’re dealing with black spots or green streaks, knowing how to remove mould from house siding effectively and safely is crucial for maintaining your home’s beauty and structural integrity.
Understanding Mould on House Siding
What is Mould and Why Does It Grow on Siding?
Mould is a type of fungus that thrives in damp, dark, and humid environments. House siding, especially in shaded or poorly ventilated areas, can become the perfect breeding ground for mould when exposed to moisture. Rain, dew, and even sprinklers can leave water on your siding, and when this moisture doesn’t dry quickly, mould or mildew can develop.
Common Types of Mould and Mildew Found on Siding
The most common types of mould found on siding are:
- Black mould: Often appears as dark black or brown spots and is notorious for its potential health risks.
- Green algae or mildew: This is more common on siding and appears as greenish streaks or stains.
- White mould: A powdery or chalky substance that can grow on vinyl or wood siding.
Health and Structural Risks of Mould Growth
Mould isn’t just a cosmetic issue. It can:
- Trigger allergies and respiratory problems, especially for those with asthma or sensitivities.
- Weakened siding materials like wood lead to rotting or deterioration over time.
- Spread to other parts of your home if left untreated, escalating the problem.
Signs of Mould Infestation on Your Siding
Look out for these symptoms to identify mould:
- Discolouration: Green, black, or white patches or streaks on the siding surface.
- Musty smell: A damp, unpleasant odour around your home’s exterior.
- Water stains: Persistent moisture spots or streaks on siding, which could indicate underlying mould.
Preparing for Mould Removal
Before jumping into the cleaning process, preparation is essential to ensure safety and effectiveness.
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Safety Precautions
When dealing with mould, always prioritise your safety by wearing:
- Gloves to protect your hands.
- Goggles to prevent splashes from irritating your eyes.
- Masks to avoid inhaling mould spores.
- Protective clothing to keep your skin from coming into contact with mould or cleaning chemicals.
Protecting Nearby Plants and Landscaping
Cleaning solutions, especially bleach, can harm plants around your home. Use plastic drop cloths or tarps to cover landscaping and ensure no runoff damages your greenery.
Choosing the Right Day for Cleaning
Pick a day that is:
- Overcast, so the cleaning solution dries slower and has more time to work.
- Wind-free, to prevent overspray and make cleaning easier.
Tools and Materials Needed
Gather the following tools for the job:
- Spray bottles or garden sprayers
- Soft or nylon brushes
- Garden hose or low-pressure pressure washer
- Cleaning gloves, goggles, and masks
- Cleaning solutions (homemade or commercial)
Effective Cleaning Solutions for Mould Removal
Different cleaning solutions work for other needs. Here’s a detailed breakdown of your options:
Bleach Solution
Bleach is one of the most effective cleaners for mould. Mix 1 part bleach with 3-4 parts water and apply it to your siding. This solution kills mould spores and removes stains effectively. However, be cautious as bleach can harm plants and discolour certain siding materials.
Vinegar Solution
A natural, eco-friendly alternative, vinegar can be mixed in equal parts with water. It’s safe for plants and siding, and works well for light mould removal.
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Oxygen Bleach Solution
Oxygen bleach is a safer alternative to chlorine bleach. Mix oxygen bleach powder with water, following the manufacturer’s instructions. It’s biodegradable, safe for plants, and gentle on siding, making it a great option for eco-conscious homeowners.
Commercial Mould Removers
Pre-made mould removers are readily available at home improvement stores. These products are convenient and effective, though they can be more expensive. Always follow the manufacturer’s instructions for the best results.
Comparison of Cleaning Solutions
SolutionEffectivenessSafety for PlantsEase of Use
Bleach Solution High No Moderate
Vinegar Solution Moderate Yes Easy
Oxygen Bleach High Yes Easy
Commercial Cleaners High Varies Easy
Step-by-Step Guide: How to Remove Mould from House Siding
Follow these steps for a thorough and safe cleaning process:
Inspect the Siding
Examine the siding to identify the extent of mould growth. Check for moisture issues or leaks that may be contributing to the problem.
Protect the Area
Cover plants, and close windows and doors near the cleaning area to prevent overspray. Use drop cloths to protect landscaping.
Apply Cleaning Solution
Fill a spray bottle or garden sprayer with your chosen cleaning solution. Spray the solution evenly over the affected areas.
Let It Sit
Allow the solution to sit for 5-15 minutes. This gives it time to penetrate and loosen mould spores.
Scrub the Surface
Use a soft or nylon brush to gently scrub the siding. Avoid using abrasive tools that could scratch or damage the material.
Rinse Thoroughly
Rinse the siding from top to bottom using a garden hose or low-pressure washer. This prevents streaking and ensures all residue is washed away.
Repeat If Necessary
For stubborn mould patches, repeat the process until the siding is clean.
Tips to Avoid Damage:
- Keep the pressure washer on a low setting.
- Maintain a safe spray distance (at least 3-4 feet).
- Spray at a downward angle to avoid forcing water behind the siding.
Preventing Mould Recurrence on House Siding
The best way to deal with mould is to prevent it from coming back. Here are some tips:
Improve Ventilation
Trim overhanging vegetation and allow more sunlight and airflow around your siding.
Regular Maintenance
Schedule routine cleanings for your siding to remove dirt and moisture before mould has a chance to grow.
Keep Gutters Clean
Ensure gutters and downspouts are clear to prevent water buildup near your siding.
Use Mould-Resistant Products
Treat your siding with mould-resistant paints or coatings for added protection.
Special Considerations for Different Types of Siding
Vinyl Siding
- Avoid using high-pressure settings to prevent cracking.
- Use mild solutions to avoid discolouration.
Aluminium and Steel Siding
- Use non-abrasive brushes to prevent scratches.
- Avoid acidic solutions that could corrode the material.
Wood Siding
- Be gentle to avoid splintering or stripping paint.
- Ensure wood siding is completely dry after cleaning to prevent rot.
When to Call a Professional
If mould covers a large area or if the siding is severely damaged, it’s best to hire a professional cleaning service.
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