As veteran roofers know, coating gravel built up roofs or “alligatored” flat roofs can be a daunting task. One of the main benefits of silicone coatings is that they create a seamless membrane. Silicone’s seamless membrane is what gives it its waterproofing capabilities. Rocky or bubbled surfaces make achieving this seamless membrane difficult as the silicone will find its way to the bottom of these cracks and crevices. Because of this problem, our research and development team created SL 800 – a self-leveling silicone designed specifically to help flatten rocky or bumpy roofs, giving you a smooth surface over which you can apply the topcoat, while keeping costs down for the client.
The Issue with These Roof Types
In the past, roofing contractors used exorbitant amounts on silicone to coat roofs like these. A normal amount of silicone on a gravel built up or alligatored roof will not suffice. The coating will flow down in to the cracks, leading to an undesirable thin final coat. As with any roof type, if you apply too little silicone, the life of the restoration could be shortened. Thus, roofers would use more and more coating to achieve the desired thickness. Unfortunately, using 3-5 times the normal amount of silicone can drive the price up quickly and make pitching coatings on these roof types difficult.
The solution to this problem is our Surface-Leveling Coating. SL 800 is specifically formulated to be less expensive than our silicone roof coating. You don’t need to worry about using unnecessary amounts of silicone to compensate for a rough roof surface. This will keep project costs down while offering you a long-term, high performance solution. Additionally, it has a lower viscosity, meaning it can migrate to the low parts of the roof. This property allows SL 800 to fill every crack and crevice.
It is important to note, however, that SL 800 was not made to perfectly level the roof substrate. It was designed to establish a much smoother surface for silicone application, not to completely smooth out the entire roof. After using SL 800 you will still see some bumps from where the gravel lies. The roof will now be smooth and level enough to achieve proper millage and a seamless membrane.
SL 800 Application
- Remove all loose gravel
- Power wash the surface of the roof
- Conduct a moisture survey and replace wet material
- Apply P-160 Bleed Block Primer (Not necessary for adhesion but can be used to maintain the bright white color of HS 3201)
- Spray apply SL 800 Surface Leveling Coating
- Apply HS 3200 Silicone Roof Coating
Another optional step is to apply the PM Pro Grip Walkway System. One major benefit of gravel BURs is that they are a non-slip substrate. If you want to maintain this feature, you can apply our walkway coating and granules to high traffic areas. See our blog from last week for more installation details.