Masonry - painting garage and wall etc

[themoo]

I'm in a period of unemployment and trying to stop myself going crazy by doing things around the house. I'm focusing on my decking and my garage. With my friend's pressure washer I am cleaning off the decking and the garage with a view to repainting both.

I think there is a small leak in my garage roof so I'm going to hop up on that as well and clean that off, and take a look.

My questions are:
- should I clean the garage roof off before the decking? I'm conscious that it's going to rain soon and I want to protect my decking but also I figure I'll need to wash it again when I've washed crap off the roof... and if I wash it again I will then need to paint it again as the washer has blasted off the paint...
- does the garage wall need to be squeaky clean before I repaint? (it hasn't been cleaned for years and is already much better, but it isn't totally white
- do I need to do anything special with the bits which are flaking off? I had a plastering chap round and he said I just needed to paint it rather than do any rendering. I've never done anything like this before so any advice is gratefully received!

Thank you.

 

[Wayners]

Looks clean already so no.
I just used large sponge and water and washed over.
Fill with masonry filler.
Sponge smooth.
Paint wall.
Read the application data sheet online for the paint products. You will find answers

 

[themoo]

Thank you very much! It's taken a while but I am pleased with the results and am tackling our shared wall next. That's a lot dirtier but I have done the best I could with the power-washer and I'll just apply several coats if needs be.