Published by: CA Wash Pros
Last Updated: 2025-12-5
We’re often asked by our customers how to remove mold and algae from siding. It’s a common problem faced by Bay Area homeowners. Aside from cosmetic impacts, mold and algae can cause material damage and deterioration.
We understand you want to keep your home’s exterior always looking fresh and in good condition. If you’re looking for ways to get rid of mold and algae from walls, you’re in the right place.
In this guide, we’ll explain two approaches to mold and algae removal: DIY cleaning and Pro house washing. While there are different areas where mold and algae can grow, we’ll focus on your home’s siding here.
What Does Mold and Algae Look Like?
The first step to removing mold and algae is being able to spot them. If you don’t know what you’re seeing on your siding, it’s hard to treat it correctly. It helps to know whether you’re dealing with mold and algae or just plain dirt and debris.
Mold appears as black streaks or spots that have a slimy and fuzzy texture. Algae looks like green streaks that have a slimy, plant-like texture.
How Does Mold and Algae Grow?
Mold Growth
- Moisture or humidity
- Organic material (wood, drywall, paint, dirt, etc.)
- Low to moderate sunlight
- Warm temperatures (some mold can grow in cooler climates too)
Algae Growth
- Moisture
- Sunlight
- Carbon dioxide and nutrients from rain, dust, or debris
Home Factors that Contribute to Mold and Algae Growth
Excess Moisture: Excess moisture can come from local weather conditions, misdirected lawn sprinklers, and big trees that cast constant shade.
Dirty Siding: Dirt, dust, and organic debris trap moisture and also act as a food source for mold.
Water Damage: When water overflows due to gutter clogs or roof leaks, it goes into unwanted areas such as the siding. Poor water drainage can make your siding damp and moist for long periods of time.
How To Get Rid of Mold and Algae on Your Siding
There are two ways to eliminate mold and algae: DIY cleaning and Pro house washing. Let’s discuss them.
DIY: Algae and Mold Cleaning on Siding
It’s possible to remove mold and algae using consumer-friendly cleaning solutions and a simple household garden hose. Here’s a step-by-step on how to do a DIY cleaning:
Step 1: Prepare the materials and safety gear
For cleaning:
- a consumer-friendly product for mold and algae removal
- garden hose
- ladder for hard-to-reach areas
For protection:
- Wear protective gear to avoid exposure
- Goggles, N-95 masks, long-sleeved shirt, protective gloves , long pants, waterproof boots or closed-shoes
*Make sure you’re only working on spots you’re confident that it’s safe to clean. Otherwise, contact a professional for expert house washing services.
Step 2: Prepare the surface
Inspect the whole area and identify which spots you need to work on. Remove any plants, pets, or furniture that you don’t want to get wet during the cleaning.
Step 3: Spray out the solution on the affected area
Connect the consumer-friendly product to the garden hose and spray out the solution to the area with mold and algae infestation. You can test it on a hidden spot to see how it works before applying it on the whole area.
Let it sit for however long the solution instructions say.
After that, thoroughly rinse it off with water. That should help remove the mold and algae on your siding.
Safety Check: Pressure Washing
Be extra careful when pressure washing your siding. Using the incorrect tip or getting too close can risk scarring the paint (which means it leaves markings) or completely remove the paint itself.
Pro: House Washing for Mold and Algae Removal
While DIY is always possible, there are instances when you need to call a professional for a house washing service.
House washing removes mold and algae on your siding using soft wash cleaning. We recommend professional house washing for safe and effective results.
House Washing Service Options
We offer two options tailored to your needs.
Tier 1 House Wash
How it works: Power washing using only water and our house wash adapter
Best for: Regular dust and dirt buildup
Tier 2 House Wash
How it works: Power washing using house wash adapter with a heavy duty soap and biocide treatment
Best for: Spiderwebs, mildew, mold, algae, and other stains
Note:
We also include a basic window cleaning which is a basic pressure washing of windows and screens using the water that comes out of the spigot.
A detailed window cleaning is a separate service with a different service fee. In this process, we remove the screens and a soft bristle brush and purified to ensure a streak-free, spotless finish.
Benefits of Professional House Washing
- Mold and Algae Removal on Different Sidings: We clean concrete, brick, flagstone, vinyl, aluminum, stucco, and wood.
- Proper Tools and Equipment: We use a special house washing adapter that helps protect the house by turning the pressure down while keeping its effectiveness against dirt and grime.
- Soft Wash for Mold and Algae: We use very low water pressure (60 to 120 psi) and apply a biocide treatment to kill off mold and algae.
- Fully-Insured Service: Enjoy peace of mind knowing that your property is covered and our technicians are protected with workers’ compensation insurance.
- Save Time and Effort: We do the tedious task so you can skip it yourself and spend more time with other things.
Signs You Need A House Washing Service
- Large infestations covering more than half of exterior walls or entire sides of the house.
- Recurrent mold growth after repeated DIY cleanings
- Safety risks from lack of experience, inaccessible and high areas, misuse of cleaning solution.
Maintenance Tips to Prevent Mold and Algae Growth on Siding
Keep Gutters Clean and in Good Condition
Clogged or damaged gutters cause water to overflow and run down your siding, creating constant moisture. Regular gutter cleaning ensures leaves and debris are thoroughly removed and rainwater is draining properly.
Trim Trees to Reduce Excessive Shade
While we love trees for improving air quality, overhanging branches can cast unnecessary shade and contribute to moisture retention on your siding. Trim back overgrown trees, shrubs, and branches near your siding to help surfaces stay dry.
Schedule Regular House Washing
In the Bay Area, we recommend house washing every 1 to 3 years, depending on your home’s location. Homes under large trees or in high-dust areas are more prone to mold and algae buildup and require more frequent cleaning. We don’t advise going longer than 3 years between cleanings for any home.
Redirect Water Sources
Make sure that your lawn sprinklers do not constantly wet your home’s exterior. Position them away from siding and foundation walls.
Book A Professional House Washing Service
If you’re confident in cleaning mold and algae by yourself and you have extra time, then you can proceed with DIY cleaning. But if you want to save yourself the trouble and avoid damage risks, then you should opt for professional house washing instead.
At CA Wash Pros, we make algae and mold removal on siding convenient, safe, and effective. With comprehensive and fully-insured services, we keep your peace of mind knowing that you can trust us all throughout.
To get a FREE, no-obligation quote for house washing, contact us at 408-800-3692 or submit your basic information in our online quote form.