Green algae is one of the most common exterior problems in the Fraser Valley’s damp climate. Here’s the safest way to deal with it.
The safest, most effective way to remove green algae from a house exterior is a soft wash: a low-pressure application of the right cleaning solution that treats the algae rather than blasting it off. Pressure washing siding, stucco or soffits risks damage and forcing water behind the cladding.
Green algae is one of the most common exterior problems on homes in Chilliwack and the Fraser Valley, because of the damp climate, shaded areas and moisture that lingers on exterior surfaces.
We regularly remove green algae from vinyl siding, stucco, soffits, gutters, windows, fences, patios and balconies. In our experience, the safest and most effective method for delicate surfaces is a soft-wash process — not aggressive pressure washing.
Why green algae grows on Chilliwack homes
Homes here deal with moisture for much of the year. That moisture, combined with shade and a lack of regular cleaning, creates the perfect environment for algae and other organic growth.
North-facing walls
North-facing walls get less direct sunlight, stay damp longer, and are where we see green algae most often.
Large trees close to the home
Trees near the house add shade throughout the day, which keeps siding, soffits, gutters, fences and patios damp for longer. Some of the heaviest buildup we see is on homes with trees taller than the house.
Too long between cleanings
The longer algae sits on a surface, the heavier the buildup gets. Homes that haven’t been cleaned in years often have debris, moss and darker staining around the rooflines and gutters as well.
Surfaces that commonly get green algae
- Vinyl siding
- Stucco
- Soffits
- Gutters
- Windows
- Fences
- Patios
- Balconies
Each needs the right process to be cleaned safely. Siding, stucco, soffits and gutters are soft washed; durable hard surfaces like a concrete patio can take controlled pressure washing where that’s the better fit.
The best way to remove it: soft washing
Soft washing is a low-pressure cleaning method that uses the proper cleaning solution to treat and remove algae and organic buildup from delicate surfaces. That matters because most house exteriors aren’t meant to be cleaned with aggressive pressure. Our house washing service uses exactly this process.
For a deeper look at the method, read house soft washing in Chilliwack, or compare the two methods in pressure washing vs soft washing.
Common mistakes homeowners make
- Using too much pressure — siding, stucco and soffits can be damaged, and water can be forced behind the cladding.
- Using the wrong products — not every product is suitable for house washing, and poor choices lead to poor results or unnecessary risk to the surface.
- Hiring on price alone — the cheapest option often isn’t the safest or the most effective.
Should you pressure wash algae off siding or stucco?
In most cases, no. Vinyl siding — one of the most common surfaces we clean — is best handled with a soft wash. Stucco also needs care and shouldn’t be treated like concrete. Soffits, gutters and windows are best cleaned with a proper soft-wash process as well.
Why regular house washing matters here
- It keeps algae from becoming heavier and harder to remove
- It keeps the home looking brighter and better maintained
- It helps stop algae, moss and grime from becoming established
If the siding is carrying heavy algae, there’s a good chance the roof is holding moss and organic growth too. It’s worth checking for the signs your roof needs cleaning — and many homeowners book roof cleaning in the same visit.