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How to Choose a Sealant That Works

by LiveModern Webmaster last modified Jun 15, 2012 08:20 AM
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by Paula Melton last modified Jun 12, 2012

Author name:  Peter Yost Blog Category:  GreenSpec Insights Any sealant can perform well in the right application, but knowing which to pick for your job is another thing. Our guide to sealants and how to use them. High-performance polyurethane sealants are among the more expensive but have many attractive properties. Photo Credit: Fine Homebuilding When selecting a sealant , these properties are typically the most important: movement tolerance (rated by Class per ASTM C920, with 25 meaning joint movement of 25% of the linear width dimension of the sealant bead) substrate compatibility workability, particularly based on temperature paintability and its converse—substrate staining relative cost service life material constituency and hazardous content There are seven basic types of liquid sealants, largely based on their chemistries and subsequent strengths and limitations. Each sealant’s suitability to an application is based primarily on its performance properties, the properties of the substrates, and cost. Latex Latex sealants are water-based, easy to tool, easy to clean up, paintable, and relatively less expensive than other types of sealants. Some premium latex sealants may be appropriate for exterior use (appropriate service life) and are rated for movement in classes 12½ and 25. Latex sealants may be best suited to interior finish applications. Acrylic Acrylic sealants are also paintable but are solvent-based and more difficult to tool. They are used more in commercial and exterior applications than latex and have very limited movement capacity (Class 7½). Acrylic sealants tend to be used in commercial construction in low-movement joints. Their cost tends to be in the low to moderate range. Butyl Butyl sealants are solvent-based, synthetic rubber materials demonstrating strong adhesion to a wide variety of substrates. They have excellent weathering characteristics but tend to be stringy and difficult to apply. They generally have limited movement accommodation (Class 7½ ). Butyl sealants are sometimes used in curtainwall systems where adhesion to rubber materials is required. The cost of butyl sealants tends toward the moderate range. The next group are sometimes called “high-performance” sealants and are most often used in commercial building assemblies. read more






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