Polyurethane Sealants And Silicone Sealants

The two most often used sealants on the market are polyurethane sealants, and silicone sealants. Each falls into the category of an elastomeric material and are used to fill gaps and keep water and air out. They also both allow for expansion and contraction, and can allow for up to 50 percent movement. Despite their similarities, these two kinds of sealants also have significant differences that make them each suitable for different types of applications. Here’s a closer look at both silicone sealants, and polyurethane sealants.

The Chemical Level

As their names suggest, polyurethane and silicone sealants are drastically different chemically. This difference means each material will break down differently over time, and react differently in different environments. Polyurethane is an organic material, while silicone is inorganic. That’s important because when subjected to UV light from the sun, inorganic materials will be less reactive than organic materials. Over time, the polyurethane sealant will revert to its natural state and change properties, which will render it ineffective for sealing the area.


As you may have guessed, the chemical differences make the lifespan of each sealant quite different. Typically, you can expect a polyurethane sealant to last 5 to 10 years, and the exact lifespan will depend on how much sunlight it was subjected to, the changes in temperature, and how often it needed to expand and contract. Silicone sealants will typically last at least 20 years, and many manufacturers even offer 20 year warranties to protect you in case your sealant wears out faster.