Hi, I am wanting to re render the back of my house which is made of brick (7x8mtrs) but unsure on keying the render on to the brick work and what mix to use on the scratch coat and what mix to use on the finish coat, also if i use a sovereign water proofer what ratio should I use and and which coat should I apply it, is there any need to use lime as I a have read afew topics about it and not sure, any help would be great