You need to clean your exterior home properly before you do any coatings. Make sure you do this. You do not need to use high PSI to achieve a clean home free of mold, algae, dirt and pollutants. use 16ounces of Simple Cherry
, 3.5 Gallons of 12.5% SH and fill the rest of the 5 with water. Only use the black tip for applying chems to apply and rinse your home.
This will clean your windows and leave them streak free as well as remove any green and black on your home. It will be paint prep ready to prime and finish.
As a Allentown Paint Contractor
, we would use a bonding primer followed by an entire caulking of the house. We would allow it to dry in for a day and then coat it with a 100% acrylic latex coating from Sherwin Williams or Benny Moore.
This is a generic answer, but I do not know all the details.