Chipped back a lower render to a dashed wall (this was a 2nd coat - left is a scratched 1st coat) I understand a 5 to 1 mix is about right. I understand that I might need a lime mix (what is the substitute for lime - I have only about 5 yards to cover to complete this job. The important ? is mixes and do I need a water proofer, how much and a substitute for lime. I will take a pic of the area to give you an idea