I have recently done a repair to the back wall of my ruin of a garage and it is topped with a 2ft timber frame (5 meters long) which I will clad in plywood and then attempt to weatherproof. No one much sees it as it will be facing the end of a neighbours very long garden. Can I just pin roofing felt down the 2ft height so it drips free of the block wall below? I would like it to last a good while as access is awkward. The prevailing winds tend to blow the rain clear of this wall as its roughly north facing in London. What would be the simplest way to weatherproof this wall bearing in mind that I will be up a ladder and working on my own?