The Cool Roof Store sells two very different types of silicone roof coatings, which are competing fiercely in the marketplace. The big winner in this fight has been the consumer.

In the last three years we have seen the amazing growth of silicone roof coatings in Hawaii’s marketplace, especially for flat roofs that have ponding water. The reason for this is no mystery: Silicone can withstand ponding water for an indefinite period of time without peeling. It also does not chalk or “sacrifice” as it ages — unlike water-based acrylic coatings.



For that reason Gaco, the oldest and largest manufacturer in the business, offers a 50 year product warranty — previously unheard of in the roof-coating industry.

However, there is also a commercial brand of silicone roof coating that is very popular. This “solvent-less” silicone is quite different in its composition, and it comes with a 50 year material warranty.

GacoRoof silicone

The more well known consumer brand is GacoRoof silicone. It has a solids content of about 70 percent silicone and 30 percent solvents. This high-solvent content makes GacoRoof much easier to apply because it dries slower and allows more time for the homeowner to properly work the coating into the roof surface.


GacoRoof also has a longer “shelf life,” which is the time you have to use up your coating before it skims over and becomes useless. This is not a small virtue when you remember that a 5 gallon bucket of coating costs more than $200. In short, it’s easier to use and very forgiving. It is also less expensive per bucket. If you use the manufacturer’s suggested rate of 2 gallons per 100 square feet over a smooth surface, you will end up with 22 dry mils of cured silicone. This is a tough coating that will stand the test of time.

NXT Silicone and Tropical Silicone

Let’s look at the professional grades that are made by NXT Silicone and Tropical Silicone, as well as the commercial grade coating that Gaco makes under the name GacoFlex S-20. They are 96 percent solids versus 70 percent for the residential market. When you use the same 2 gallons per 100 square feet, you end up with a cured coating of 40 mils. NXT and Gaco both warrant the material for 50 years, just as GacoRoof does. When these cure out, they are glossier and have a slicker surface than GacoRoof. This can be easier to clean if you have dirt or mildew built up on your roof. On the other hand, if you climb up on your roof to pick mangoes or inspect your solar system, it can be extremely slippery when wet (caution is advised).


These solvent-less coatings will cure quickly on a hot day — sometimes too fast for novice users. However, when they are cured they will have a tough silicone finish that will be about 40 dry mils versus 22 dry mils for solvent-based coatings. They also can take unlimited ponding water without any damage.


The Cool Roof Store sells both coatings and will be happy to show you all the tricks of the trade that can save you from making an expensive mistake.

contact // 591-1900
address // 575 Cooke St.
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