Silicone Recoat Over Modified Bitumen

The Challenge

Representatives of a high school in the Mobile, Alabama area began to report numerous leaks in their 100,000 sq. ft., modified bitumen roof. In order to learn more, an American WeatherStar approved contractor was asked to survey the roof. During the inspection, the contractor was able to identify the source of the leaks. It was also discovered that the roof had previously been coated with silicone system about ten years earlier.

Aside from a few small problem areas, the existing silicone top coat was found to be mostly intact. It was later determined that the leaks occurred because the seams of the modbit roof were not properly addressed during the initial silicone system install. With any coatings project, seams and other flashing details are especially important to address as they are the most likely spots for leaks to occur.

The Solution

It was determined that a recoat with the Envir-O-Sil system from American WeatherStar could restore the roof. The first step of the installation was to pressure wash the roof to remove any debris and loose coatings. Next, Terminator 622, which is a waterproofing product that adheres especially well to silicone, was used for select problem areas of the roof in need of repair. All seams, fasteners, penetrations, and transitions were then coated with Silicone Brush-Grade 422.

Once the problem areas and flashing details were addressed, a base coat and top coat of High Solids Silicone 412 was then applied to the roof. This low VOC product forms a weather resistant, rubber-like seal and provides the roof with excellent UV protection. 

The Benefits

Obviously, the main objective of this project was to stop the roof from leaking. Proper treatment of the seams and other flashing details during installation will help ensure the long-term success of this system.

Once the project was completed, the roof received another ten years of warranty protecting it from any future leaking problems. For the school system, which owns the building, the Envir-O-Sil system was a much more cost effective alternative to a full roof replacement.

Project Summary:

This high school in the Mobile, Alabama area was experiencing roof leaks in their previously restored, modified bitumen roof. For this project, the Envir-O-Sil system and some much needed repair turned out to be the perfect solution.


Project Specs:
  • Roof Type: Modified Bitumen
  • Size: 100,000 sq. ft.
  • Location: Mobile, AL
  • System: Envir-O-Sil

System Products:

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