Coverage Rates for Silicone Roof Coating Restorations
Coverage rates for silicone restorations can be puzzling for roofing contractors new to silicone. Since silicone can be applied to so many substrates, it can be challenging to keep up with the proper coverage rate for each one. The last thing you want to do while quoting a roof is underestimate the amount of coating needed. This can greatly delay the project timeline and amount of profit made for you! As an additional resource to our online coverage guide, this blog will look at each substrate and what the coverage rates are for each.
How Does the Substrate Affect the Dry Mils?
The biggest factor affecting dry mil (*1) requirements is the texture of the substrate. Each substrate has unique features that give it a smoother or rougher texture. This, in turn, can affect the amount of coating needed for a warranty, which directly affects the coverage rate for each substrate. A smooth surface (single ply, metal, etc.) requires less silicone since the silicone sits nicely atop the non-textured substrate. A rougher surface (mod-bit, BUR, etc.) will have more texture/small crevasses requiring a bit more silicone to fully coat the substrate.
*1 If you are unsure what dry mils are, click here for a brief explanation.
PVC, TPO, Hypalon, and EPDM
Each of these membranes are relatively smooth with little texture. This means our silicone roof coating can be easily applied and the same dry mil recommendation pertains to each of the 4 single-ply membranes. We require that the installing contractor apply the silicone coating at a rate of 20 dry mils for a 5-year warranty, increasing 5 mils for every 5 years of additional warranty desired. This means for a 20-year warranty, 35 dry mils is the recommended thickness.
Our silicone coating is also easily applied over existing metal roofs. Metal roofs are even smoother than single-ply substrates, so you need even less silicone for the same warranties. Warranty terms for metal roofs begin at 15 mils for a 5-year warranty, increasing 5 mils with every additional 5 years. If you’re looking for a reference, you can find a material calculator on the side bar of all our products!
NOTE: Since metal roofs can have standing seams, this can increase the actual square footage needing to be coated. These kinds of metal roofs require more silicone than others, so it’s always best to consult your Regional Manager when quoting metal roof jobs.
Mod-Bit and Smooth BUR
As you know, mod-bit and smooth BUR roofs have quite a bit of texture. In addition to the texture of the substrates, they are also thick materials with seams. Where these seams meet is even thicker. For these substrates, you will first need to coat each seam with 20 mils of silicone before the entire roof is coated. Afterwards, apply 25 mils of silicone coating to the entire substrate. The general rule applies to this substrate as well: increase 5 mils for every 5 years of warranty life.
Mod-Bit and Smooth BUR have the second highest required dry mils, right behind Gravel BUR. After ridding the roof of loose rocks, you’ll need to apply SL 800 Surface Leveling Coating at a rate of 3 to 6 gallons per square, depending on the surface texture. After applying SL 800 there should be no rock protruding more than a maximum of ¼” out of the coating. SL 800 is a less expensive material than our HS 3200 series and will ensure that you use less topcoat while still achieving a level roof surface. A 5-year warranty for this roof requires 30 dry mils. Additionally, we offer up to a 10-year warranty for Gravel BURs.
Concrete substrates offer a lot of protection from harsh weather because they resist impact well. However, it is slightly porous and has the tendency to absorb moisture which can lead to major issues down the road. This is one reason PM silicone over concrete is so beneficial. Our line of silicone products adhere extremely well to concrete roof decks and we have recently introduced our P-140, 2-part epoxy primer specifically for concrete roofs. Although primer is rarely necessary on concrete roofs, this primer will ensure proper adhesion on even the trickiest concrete roof. We offer full 5 to 20-year warranties for this substrate starting at 25 mils for a 5-year up to 40 mils for a 20-year warranty.
If you have any questions about coverage rates and warranties, we are here to help! Be sure to reach out to your Regional Manager when discussing projects and placing orders. Next week we will be discussing how to assess leaks on commercial roofs!