If your home’s siding has developed green algae, mildew, or other outdoor buildup, you don’t necessarily need to spend hours scrubbing every panel. A simple cleaning routine can loosen the growth and make the job much easier.
Here’s a practical step-by-step method you can try.
What You’ll Need
- A garden hose or low-pressure pressure washer
- A bucket
- Warm water
- An exterior siding cleaner or oxygen-based cleaner suitable for your siding
- A soft-bristle brush or long-handled siding brush
- Rubber gloves
- A garden sprayer, if available
Step 1: Choose a Cool, Cloudy Day
Cleaning siding in direct, intense sunlight can cause the cleaning solution to dry too quickly. Pick a cooler day when possible so the solution has time to work.
Step 2: Rinse the Siding
Start at the top and gently rinse downward with a garden hose.
This removes loose dirt, dust, and surface debris before you apply the cleaner. Avoid forcing water underneath siding panels, around windows, or into vents.
Step 3: Prepare the Cleaning Solution
Mix an exterior siding cleaner according to the product’s instructions.
For a gentler homemade option, an oxygen-based cleaning product labeled as suitable for your particular siding can be used according to its directions.
Always check the siding manufacturer’s recommendations first. Different materials can react differently to cleaning products.
Step 4: Apply From Bottom to Top
Apply the solution to a manageable section of siding, working from the bottom upward. This can help reduce streaking.
Allow the cleaner to sit for the amount of time recommended on its label. Don’t allow it to dry completely.
Step 5: Let the Cleaner Do the Work
Once the green buildup begins loosening, use a soft-bristle brush only where necessary.
You may be surprised by how little scrubbing is required when the algae has been properly loosened first.
For large areas, a garden sprayer can make application much faster.
Step 6: Rinse Thoroughly
Rinse the siding from the top downward with clean water.
Keep the spray directed toward the siding rather than underneath the panels. Pay special attention to areas around windows, doors, plants, and outdoor fixtures.
Step 7: Check for Remaining Green Spots
After the siding dries, inspect it in natural light.
If stubborn patches remain, repeat the treatment rather than aggressively scrubbing the surface. Scrubbing too hard can damage certain siding finishes.
A Few Important Safety Tips
Never mix household cleaning chemicals together. In particular, never combine bleach with ammonia, acids, or other cleaners, because dangerous gases can be produced.
Protect nearby plants by wetting them with water before and after cleaning, and follow the cleaner’s label instructions regarding vegetation.
If you’re using a pressure washer, use the lowest effective pressure and keep the nozzle at an appropriate distance. Excessive pressure can damage siding or force water behind it.
How to Help Keep Algae From Coming Back
Green algae tends to return where surfaces stay damp and shaded. Keeping gutters clear, improving drainage, trimming vegetation that blocks sunlight, and fixing leaking downspouts can all help reduce recurring buildup.
The key is simple: loosen the buildup first, rinse thoroughly, and avoid unnecessary scrubbing. With the right cleaner and technique, even heavily stained siding can look dramatically fresher.
See more on the next page