How to clean rendered retaining wall?

[kmoncktom]

I’d love any tips about how to clean this wall that runs along the front of our house. I am a total newbie to DIY unsure if it’s sandstone or brick with some kind of render. There is sandstone used in other parts of the front of the house and outside. There is a heritage overlay on the facade so I want to be careful when cleaning it. I’m worried the pressure washer might do damage. Thanks so much. 

[MitchellMc]

Welcome to the Bunnings Workshop community @kmoncktom. It's brilliant to have you join us, and many thanks for your question about cleaning a wall.

Given your concern about the heritage overlay and the risk of damaging the wall, it might be worth considering enlisting the services of a professional who can perform a soft wash with the appropriate chemicals. While you could use a high-pressure washer, the cracks and render on the wall make it a fine line between effectively cleaning off the moss, debris, and dirt and potentially damaging the render or surface underneath. A professional will have the right tools and expertise to clean the wall safely without causing any harm to the structure. 

Please let me know if you have any questions.

Mitchell