OVER WHAT SUBSTRATES DOES SILICONE WORK?
On this blog, there are many posts stating that silicone works over a large number of substrates. Sometimes we delve into specifics, sometimes we leave it in more general terms. In this post, we are going to explain in detail which substrates you can coat with silicone. If you’re considering installing a completely new roof system, read this post first to see if your substrate is a good candidate for a silicone roof coating restoration.
Substrates with PM Silicone Specs
We have written project specifications for only a select number of substrates. Over these substrates, our success rate is virtually 100%. On the few roofs that we have experienced issues, only about .1% of the total roof requires improvements. More importantly, on the roofs that we have experienced issues, every single one of them has been an issue with the old substrate failing or material not being applied correctly. Our silicone has yet to fail and be the culprit in a warranty claim since inception. With that type of product performance, you can count on a good roof when you install our silicone in accordance with our specs. Below is a list of our existing product specifications:
RCR over:
Each of these systems, with a couple exceptions, has specifications required to obtain 5, 10, 15, and 20-year warranties. If your existing roof is one of the systems above, we can confidently say that you will have success with a silicone roof coating restoration (remember our .1% warranty claim rate?). These specs vary slightly from system to system. On some of them we recommend a primer (primarily asphalt-based substrates as the asphalt can leech materials into the coating, causing it to turn yellow), some of them require fleece tape on seams while others don’t. So while there are minor variations, the general process is 1. Clean the roof, 2. Prep the roof, 3. Coat the roof.
Substrates Without Specs That Are Good Candidates
There are still more substrates that are good, even great, candidates for a silicone roof coating restoration, but we don’t yet have enough testing and real-world data to provide specifications for them. As we have gained experience working with substrates or have seen more demand in the market, we have added specifications in the past and will continue to do so. That is to say, if your roof is listed below and you’d like to perform a silicone roof coating restoration and receive a warranty, contact your sales rep and we can work with you. We can’t guarantee we’ll be able to produce a spec, but we will always take a look.
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Aged asphalt – Aged asphalt roofs (not shingles) are very similar to a modified bitumen roof. Because of their similarities, we have seen success with aged asphalt. However, there are variations in the asphalt industry that require a little more caution, so we don’t specify this system.
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Cap sheet – Nearly exactly the explanation as above. Granulated cap sheet roofs are extremely similar to mod-bit.
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Skylight – We have a product designed specifically for fiberglass skylight applications. There are again too many variations among skylights to write an across–the-board spec, however, so we do not have one yet.
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Parapet walls – Parapet walls are typically made of the same material as the substrate. Occasionally they are made of bricks, concrete, or another material. If your roof substrate has a spec, the parapet walls most likely “adopt” that. But with so many variations, it’s hard to write a singular spec. The vertical surface is what many people think stumps silicone, but that is no problem.
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Camper/RV – Typically made of single-ply (for which we have 4 specs), camper and RV roofs are generally not a problem. There are great variations in the roofs of these vehicles, however, so no spec has been produced yet.
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Steel – Almost identical to metal roofs, there are minor variations and lower demand for specifically steel roofs.
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Aluminum – Same as steel.
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OSB – Think plywood. This is not a recommended application due to weather, structural soundness, and building code concerns. However, if the outer layer of your roof is OSB (this would only be after tear-off or installing OSB, we can 99.9% guarantee your existing substrate is not OSB), silicone can adhere and provide waterproofing capabilities. We have had customers use this system in the past with great success, but we don’t recommend it.
Substrates That Are Not Good Candidates
To date, we have only discovered one substrate over which silicone cannot successfully be applied: Coal tar pitch. The reason for this is that coal tar pitch is designed to be “self-healing”. Each day when the material heats up, it re-emulsifies and the tar heals any cracks, splits, holes, or other issues. The bad news is that this process continues underneath our coating, which prevents it from adhering to anything stable. The good news is a coal tar pitch is nearly indestructible, so if you have one you are in good shape.
Conclusion
As you can see, silicone is an extremely versatile product. There are many systems for which we have precise specs, and even more that silicone works over but we don’t yet have a spec. If your roof substrate falls on either list, contact us today to see how we can help you restore it.
