The short answer: wash it like a small house
Most backyard ADUs and guest houses in Los Angeles are built like the main home: stucco or fiber cement siding, vinyl windows, a small roof, and a concrete or paver path to the door. That means the right cleaning method is the same one you would use on the house. Soft wash the walls with a mild detergent and low pressure, then use proper pressure on the flatwork.
The difference is scale and access. An ADU is small, often tucked behind the garage or along a narrow side yard, and it may have a tenant living in it. Those details shape how and when you clean it more than the walls themselves do.
What builds up on a newer ADU
A lot of LA ADUs are new, and new construction leaves its own mess. Fine stucco dust, drywall dust tracked out the door, paint overspray on concrete, and mud splashed onto the lower walls during the build are all common. Much of this rinses off easily if it is handled before it bakes on through a hot Valley summer.
Location matters too. A unit set deep in a backyard often sits in partial shade under trees, with less airflow than the main house. Shaded walls and paths stay damp longer after winter rains, which is where green algae and dark staining show up first. Units near a busy alley or driveway pick up road grime instead.
Washing the walls without damage
Stucco is porous and can be gouged or have its color worn by a narrow high-pressure tip. The safer approach is to wet nearby plants first, apply a cleaning solution, let it dwell long enough to loosen the dirt, then rinse from the top down with low pressure so dirty water does not run over areas you already cleaned.
If your ADU is brand new, ask your builder when the stucco or paint is fully cured before any washing. Fresh finishes need time, and cleaning too early can cause problems that look like dirt but are really finish damage. Around windows, keep the spray angled down so water does not get pushed past the seals.
Do not skip the path to the door
For a tenant or guest, the walk to the front door is the first impression. Side-yard walkways in LA tend to be shaded, narrow and lined with plants, so they collect leaf stains, dirt and algae. A surface cleaner gives an even finish on concrete without the stripes a wand can leave. We walked through one of these jobs step by step in our side yard walkway before and after post.
Check stepping stones, pavers and any small patio or landing at the entry too. Uneven pavers and loose sand in the joints need a lighter touch and may need re-sanding after cleaning.
If you rent it out
The best windows for cleaning a rental ADU are between tenants and before you take listing photos. Clean walls and a bright path make a small unit look cared for, and it is much easier to work when nobody is coming and going.
If someone lives there now, give them notice, ask them to close windows and move anything they keep outside, like shoes, mats or a bike. Wash water and detergent should never be sent into the street gutter. Los Angeles Municipal Code section 64.70.02 prohibits discharging untreated wash water from paved-surface washing into the storm drain system, so plan where the runoff goes.
Pricing, and why bundling with the main house makes sense
As of October 2026, our house washing rate is $0.35 per square foot of exterior wall, and walkway and sidewalk cleaning is $0.55 per square foot. Every visit has a $195 minimum. A small ADU often lands under that minimum on its own. For example, 400 square feet of wall at $0.35 comes to $140, so the visit would still be billed at $195.
That is why most owners clean the ADU on the same visit as the main house or driveway. You get more work out of one trip, and booking two services earns a 5 percent bundle discount, three or more earns 10 percent. At Say Wash It, the flat price is confirmed with you before any work begins, and the instant quote calculator on this page gives you a starting number in a minute.
What you can handle yourself between cleanings
A small ADU is easy to keep up. Sweep the path weekly, clear leaves from gutters and roof valleys before the rainy season, trim plants back a few inches from the walls so they dry out, and rinse off light dust with a garden hose after Santa Ana wind events. Save the full wash for once a year or when the unit changes hands.
Key points
The short answer: wash it like a small house
Most backyard ADUs and guest houses in Los Angeles are built like the main home: stucco or fiber cement siding, vinyl windows, a small roof, and a concrete or paver path to the door. That means the right cleaning method is the same one you would use on the house. Soft wash the walls with a mild detergent and low pressure, then use proper pressure on the flatwork.
Pricing, and why bundling with the main house makes sense
As of October 2026, our house washing rate is $0.35 per square foot of exterior wall, and walkway and sidewalk cleaning is $0.55 per square foot. Every visit has a $195 minimum. A small ADU often lands under that minimum on its own. For example, 400 square feet of wall at $0.35 comes to $140, so the visit would still be billed at $195.