Interesting question. Amanda saw a hack about wetting our concrete drive then covering the surface in BIO washing POWDER leaving it for 8 hours and wetting again then use a yard brush to scrub in. Then leave til the following days and hose off.
In fairness it was a cheap (€8) and easy way to clean off the green that forms over the winter.
I did wonder about doing similar to the roof of my van but I came to the conclusion that it may do a good job on the roof I might be left with streaks down the sides and front and back. So I didn’t try it.
Great for the yard too risky for the van.
