If one side of your house is noticeably greener than the rest, you are not imagining it. That green film is algae, and in Northeast Ohio it almost always shows up first on the north-facing or shaded side of the home.
What causes green siding?
Algae needs three things: moisture, shade and something to cling to. Northeast Ohio provides plenty of all three.
- Humidity. Lake Erie keeps the air moist for much of the year, especially in lakeside and west-side communities.
- Shade. North-facing walls and walls under trees rarely get enough sun to dry out.
- Wooded lots. Homes that back up to parks and reservations stay damp longer.
Why pressure washing alone brings it back fast
A pressure washer knocks the visible algae off, but it does not kill the growth that remains in the texture of the siding. Within months, the green returns. High pressure can also force water behind vinyl siding and damage paint.
How soft washing stops it longer
Soft washing applies a biodegradable cleaning solution at low pressure that kills algae and mildew at the root. Because the growth is killed rather than just knocked off, siding stays clean much longer. House washing is $0.21 per square foot.
Do not forget the roof and deck
The same conditions cause black streaks on roofs and slippery green decks. A roof soft wash and deck cleaning handle both safely, and booking 2 or more services unlocks our bundle perks.
How often should you clean?
For most Northeast Ohio homes, once every 12 to 18 months keeps algae from taking hold. Heavily shaded or wooded lots may need it yearly.
Is green siding harmful?
Algae is mostly a cosmetic problem at first, but left alone it holds moisture against the siding and trim, can stain light-colored surfaces, and makes walkways and decks slippery. On roofs, the same kind of growth causes black streaks and can shorten the life of shingles over time.
Algae, mildew or mold: what is the difference?
- Green film is almost always algae.
- Black spots or streaks are usually mildew on siding or a type of algae on roofs.
- Fuzzy or raised growth on shaded wood can be moss or lichen.
All of them respond to soft washing, which is why we use the same low-pressure approach across siding, roofs and decks.
Simple ways to slow it down
- Trim shrubs and branches back from the house so walls can dry.
- Keep gutters clear so water does not spill down the siding.
- Point sprinklers away from the house.
- Wash the house every 12 to 18 months before buildup gets heavy.
What a soft wash visit looks like
We protect your landscaping, apply the cleaning solution at low pressure, let it work, and rinse everything gently. Most homes are finished in a few hours, and you do not need to be home as long as the outdoor spigots are accessible.
Frequently asked questions
Will the green come back?
Eventually, because the conditions that cause it do not change. Soft washing kills it at the root, so it takes much longer to return than after a plain pressure wash.
Can I just use bleach and a hose?
Strong mixes can harm plants, stain surfaces and are unsafe on a ladder. A professional soft wash uses the right strength and rinses everything properly.
How much does it cost to remove algae from siding?
House washing is $0.21 per square foot plus a 5% transaction fee, so a 2,000 square foot home is about $441 in total.
Where we see it most
We clean green siding all over the region, including Westlake, Bay Village, Strongsville, Mayfield Heights, Solon, Rocky River, Avon Lake and North Olmsted.
About the Author
Michael Betts is the founder of ALWAYS B.I.G. Power Washing Pros, an owner-operated exterior cleaning company serving homeowners and businesses across Cleveland and Northeast Ohio with house washing, roof cleaning, gutter services, window cleaning and concrete cleaning.
Call or text (216) 202-8264, email michael@ohiopowerwashingpros.com, or read more homeowner guides in the Curb Appeal Report.