cleaningexterior
The exterior walls of my house mainly consist of pebble dashing. I plan to clean the walls as currently there is a small amount of red dye appearing (I think this is coming from the brickwork underneath). Plus the walls are just starting to get grubby with a little moss and algae.
Is there any specific products or techniques I can use to clean up the pebble dashing?
It will work as well as the previous path has. Building the slope into the path means you don't have to worry so much about the base - one of the main reasons for a good crushed rock base is to aid in draining. Also, this is not a large slab area - it's just a narrow path, so going with a packed dirt/clay base is fine.
In the worst case, you'll shovel it back into a mesh to separate the pebbles from the dirt, and re-lay it out later, but I expect if you follow the design of the existing path you'll be just fine. It'll match better as well.
Don't re-grout, clean it! Talking with a Home depot guy last year about this and he was amazed I still had to use a brush. He shows me this stuff called oxygen bleach from Ajax. This was literally the easiest method I have ever used. Make a solution with just enough hot water to dissolve it, apply and let it sit for 15-20 min and mop off. That easy. I will never use a tile brush again. Once you get it sparkling white, you can upkeep it my adding a small amount every time you mop and you will have pearly white floors forever.
Best Answer
I doubt brickwork would leach through the typical 1" or more of mortar. It would have to be something near the surface.
A mild detergent with a mildewcide added should be sprayed on, allowed to soak per directions and then scrubbed lightly, followed by a rinse. If the red dye comes out, I would use a sealer to help the surface dry off more quickly after a rain and it will keep the walls cleaner.