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The Fascinating Science of Silicone Roof Coatings

In the last 4 years we have seen a huge rush of Hawaii homeowners towards Silicone roof coatings in place of the older water based Acrylic coatings.


Why has there been such a dramatic shift in market acceptance here? Over all, homeowners have been very happy with the bright white water based coatings of the recent past. There has been virtually no movement back to the traditional hot asphalt roofs of yesterday. When was the last time you saw a roofing truck towing a hot tar kettle behind it?

That’s because homes are much cooler now with the reflective coatings–even without the rising expense of A/C.

Then benefits of a cool, white roof- whether silicone or water based–are numerous:

  • Easier to spot and repair leaky areas or open seams.
  • Photovoltaic (PV) panels are a perfect match for cool roofs because they can be seamlessly waterproofed around the roof racking system. By the way, they also increase electricity production by 4% or more, due to lower roof temperatures of a white roof.
  • You never have to tear off your old roof and haul it to the dump at great expense. You could simply put a thin topcoat over your old Acrylic roof coating when it started to wear thin– usually every 7-15 years depending on the conditions.

Do Your Roof the Same Time You Install Solar

Now we arrive at the Silicone age of roof coatings with 50 year Material Warranties by some established Manufacturers such as Gaco and Apoc. Because silicone does not chalk or “sacrifice” over time like water based acrylics do there is the possibility that you may not have to touch your roof for many decades. Do it once and forget about it. Continuous ponding water has not effect on it. Why is silicone so durable?

Here are some of the scientific properties of silicone that you can find in Wikipedia:

  • Low thermal conductivity–your home stays cool.
  • Low chemical reactivity–grease vents from restaurants don’t touch it.
  • Low toxicity –great for water catchment on the neighbor isles. In fact it’so safe that the nipples in baby bottles are made from silicone.
  • Thermal stability over a extremely wide temperature range of −100 to 250 °C).
  • The ability to repel water and form watertight seals.
  • Does not stick to some substrates, but adheres very well to others, e.g. old asphalt or metal roofs.
  • Does not support microbiological growth. (Any mildew growth is on the surface only and can be easily cleaned off to a bright white.)
  • Resistance to oxygen, ozone, and — MOST IMPORTANTLY–ultraviolet (UV) light. This property has led to widespread use of silicones in the construction industry (e.g. coatings, fire protection, glazing seals) and the automotive industry.

If you would like to know more about Silicone roof coatings please contact us at 591-1900

3 Responses to “The Fascinating Science of Silicone Roof Coatings”

  1. Sally Arnold says:

    Silicone roof coatings really do help prevent ponding and they wear really well. We highly recommend them to our customers! – Roofing contractors, UK

  2. mark roth says:

    Thank you for putting up all the info on your website. People from around the world find it very useful. I really like the silicone sealer. One question: When/if it gets damaged, what will stick to the silicone sealer? Is there special pre-treatment of the existing silicone layer?

    I am using this product in the southeastern U.S. In researching, I found some cautions on using it in colder areas.
    In cooler climes, double check roof insulation. These coatings allow heat/cold to pass through. Uninsulated roofs, or roofs with certain insulation arrangements can allow for condensation on roof decking, leading to rot. This is related to inside moisture levels, primarily in occupied areas (vs. garage or storage units). One arrangement is foamboard insulation on top of decking, with extra layer of decking above. Other, less expensive arrangements are possible (e.g. spray foam underneath). Research them first.

    Many thanks – Mahalo


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