Let’s talk about the caulk and sealants on your roof (insert yawn here). While this may not be the most interesting topic to review, there are some things that owners, managers and engineers alike should be aware of.  Not all caulk and sealants are created equally and there are some significant variations in durability and life expectancy based on which product is used. Without proper caulk and sealants, water will most certainly migrate right into your building, no matter how amazing your insulation and roof membrane are.


Most people believe that if it comes in a cartridge, then its caulk. However, caulk is really the cheaper DIY product. Sealants provide the correct specifications (durability against elements flexibility with expansion and contraction) in order to be utilized in construction applications such as roofing. There are a number of different sealants on the market that perform at a much higher rate then those traditional caulks you can buy at the box store.

The two (2) sealants you should be most concerned about are Silicone and Urethane. Both of these are commonly used on roofing materials and both provide substantially better results compared to that of a traditional caulk.


Today, of the 113,000 metric tons of sealant used in construction, 88,500 metric tons are silicone. Almost all silicone sealants cure by exposure to moisture. Silicone sealants are usually clear or translucent, to coordinate with various colored building materials, and can also be pigmented to allow color matching. They cure faster than polysulfides and are capable of fairly deep cures.


Polyrurethane sealants are based on the reaction products of (1) polyisocyanates containing two or more NCO groups, and (2) hydroxyl-bearing molecules containing two or more OH groups called “polyols.” Urethane chemistry represents a very diverse group of polymer systems ranging from two-part to one-part moisture-cure and even one-part oxygen-cure sealants.

Single-ply membranes and longer warranty requirements induced roofing contractors to begin using the more expensive urethane sealants. Today urethane sealants are specified in many single-ply roofing details where they are used extensively in flashing, termination bars, reglets, coping and pitch pans.


The truth is that all caulks and sealants have a life expectancy just like all the other components on your roof. While you’ll need to keep an eye on the various sealants as they’ll all need to be replaced throughout the life cycle of your roof (best maintained by a roof care plan provided by a quality service provider that will address this on an ongoing basis and prevent collective failure), you get what you pay for and will be replacing more often if inferior products are used. In addition, allow only experienced people to work on sealant applications. Poor workmanship can affect a warranty or even your company’s reputation. Just as welding rod companies don’t warrant a welder’s work, don’t expect a sealant manufacturer to warrant your employees’ work.

Categories: NIR Blog