Sealants, Part 1: Don’t get stuck using the wrong sealant or application

Think adhesives, sealants and caulks are simple? In many respects they are, but don’t get fooled by the false notion that you can just slap anything between two materials and magically it works. We went to manufacturing experts to find out what you should know when selecting and using these products.


Photo courtesy of Novagard Solutions

We started with Joe Borak, Vice President of Pro Construction for Novagard Solutions. Rural Builder readers are familiar with the company’s NovaFlex roofing sealant. Borak starts by explaining the differences between sealants, adhesives and caulks before focusing on sealants, which are more commonly used by rural builders.

“Sealants provide a long-lasting weather-tight, flexible seal. Adhesives bond two substrates and can either be a hard set or a soft set. Caulks just fill holes and can shrink and crack over time,” he explained.

There are generally five types of sealant/caulk chemistries in the construction industry:

  • Silicones
  • Polyurethanes
  • Modified Silicones/Urethanes
  • Solvent Based Caulks
  • Acrylic/Latex Caulks

“All of the chemistries except silicones have carbon in their chemical makeup,” Borak said. “UV lights are attracted to the carbon and break it down over time. The degradation compromises the overall effectiveness of the seal and will cause the caulk or sealant to fail over time.”

Proper Selection
There are some general rules builders should follow for choosing the proper sealant for a particular job.

“Always choose your sealant or caulk based on the performance requirements for the application,” said Borak. “In the rural building industry, the substrates are often dissimilar and a higher performing sealant is always a good rule of thumb to have on hand. At the end of the day, the difference in price between a low-end caulk and high-end sealant is usually only pennies on the dollar. It pales in comparison to what it costs to go back on a job for a callback.”

Unfortunately, too many builders go to a big box store and grab a product off the shelf without knowing how it will perform in a given situation. It’s not entirely the builders’ fault.

“The big box stores and some lumberyards often make the same mistakes with their stocking decisions,” Borak explained. They stock many different varieties of the same sealant/caulk chemistry—different brands but basically the same type of performance, and all too often not even recommended for the applications of products they sell.”

Today’s breed of high-performance sealant chemistries have been around for several years, so the impetus has been on educating contractors and the building community to understand the current generation of sealants and how to get the most from them. “The higher performing sealant chemistries have been brought to the forefront in the last 5-10 years,” Borak said. “When you couple that with the increasing availability of colors in sealants and PVDF coated paints, you can find a solid matching color system for the consumer that will last for years.”

Proper application
Of course, application is relatively easy, but you will only get the desired performance if you work with the science not against it.

“Don’t use a sealant or caulk just because your granddaddy did 30 years ago,” said Borak. “Seek out better alternatives! Don’t be misled by general terms such as “silicone or caulk.” Do a deeper dive into understanding what the differences are between the options that are available in the marketplace.”

The fact is, there can be many varieties of the same thing, each created to do something different. For example Borak said builders might be surprised to learn that a topic such as silicone has four different varieties that make up its chemistry. “The version that everyone thinks of is the acetoxy version that doesn’t adhere to many substrates and emits an obnoxious odor during the curing process. On the flip side is a neutral/oxime cure silicone. This version adheres to many different substrates and is very user friendly,” he said.

One of the most critical aspects to proper application involves temperature and environmental conditions.

“Temperature and environmental conditions play a huge role in the sealant/caulk’s performance,” Borak noted. “Extremes in temperature can make a caulk react differently depending on the temperature; either really stiff in a cold environment and almost fall out of the tube in a hot environment. A sealant will give the user a better opportunity for a consistent gunnable product. Silicones work best in both ends of extreme temperatures. A dusty environment will wreak visual havoc with all caulks and sealants during the curing process.”

What is the future of sealants?
“The builder community will see the less favorable high VOC chemistries go by the wayside,” Borak said. “In their place will be high performing greener substitutes. The education of the construction community will continue to evolve. Understanding the role that carbon plays in the caulk and sealant chemistries is vital to achieving a long-lasting weather tight seal.” RB


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