If you've looked into house washing, you've probably seen bleach mentioned, and maybe some warnings about it. The short answer: diluted bleach (sodium hypochlorite) is one of the most common cleaners used in professional soft washing, and it's safe for most exterior surfaces when it's mixed, applied, and rinsed correctly. The problems come from using it the wrong way.
What soft washing is
Soft washing cleans with low pressure and a cleaning solution instead of high pressure alone. The solution kills mildew, algae, and other organic growth, and a gentle rinse carries it away. Because it treats growth at the root, soft washing usually keeps siding and roofs clean longer than blasting the surface with water.
Why bleach is used in house washing
The black and green streaks on siding and roofs along the Gulf Coast are mostly algae and mildew. Water alone can move dirt, but it doesn't kill that growth. A properly diluted sodium hypochlorite solution, usually combined with a surfactant that helps it cling to the surface, kills the growth so it rinses off and stays away longer.
When bleach and pressure washing go wrong
- Mixing too strong: An overly strong mix can lighten some surfaces and stress plants.
- Using high pressure on soft surfaces: High pressure on painted siding, stucco, or shingles can strip paint, force water behind siding, and damage roofing granules.
- Not protecting plants: Landscaping should be wetted before and rinsed after, and runoff should be managed.
- Mixing chemicals: Bleach should never be mixed with ammonia or acids. That's a safety issue, not just a cleaning one.
Can you soft wash with a pressure washer?
Yes, with the right setup. Professionals often use a pressure washer with a downstream injector or a dedicated soft wash pump, plus low-pressure tips, so the solution goes on gently. The key is that pressure stays low enough not to damage the surface.
Which surfaces need soft washing
- Painted siding, vinyl, and stucco
- Asphalt shingle roofs (roof soft washing removes black algae streaks without damaging shingles)
- Screens, eaves, and soffits
- Older homes with fragile paint or trim
Concrete driveways, sidewalks, and patios are the opposite: they can handle higher pressure, and hot water helps with oil and grease stains.
How Texas Commercial Wash does it
We choose the method for each surface. That means soft washing for siding, stucco, and roofs, and pressure washing for concrete. We pre-wet and rinse plants and rinse every surface thoroughly. Our crews are fully insured, and we serve homeowners in League City, Friendswood, Clear Lake, Webster, Kemah, Seabrook, and nearby Houston neighborhoods.
Request a quote or call/text 281-512-5223.