This was a ceiling for a screen enclosure on the back porch. I used HENRY 287 Solar-Plex for this enclosure. It requires 2 coats, according to the manufacturer, it was waterproof after the first coat, then applied a second. I went as far as a third coat, because the product is so thin - I wanted a 4th coat, but it may have adversely affected the performance of the material after the 3rd.
I used a similar product by APOC last year. APOC 243 Advanced Elastomeric White Roof Coating - in the future, for any roof waterproofing, I'll be using APOC. It's a thicker material and covers in 2 coats, instead of 4. Using a higher quality product uses less material and saves costs.
Also, removed the original remaining parts of the original leaf filter on the gutter, repaired all of the downspouts around the house as well - using 4" vinyl downspouts - all materials were acquired from the Home Depot as they had all of the materials that I needed - single source!