Problem Joints No More

07/06/2005 |

Learn how and where pre-cured silicone sealants are most useful

While liquid-applied sealants have been used successfully in the construction industry for many years, pre-cured joint sealants are becoming more popular because of their many benefits. Pre-cured joint sealants are produced by extruding sealant material and allowing it to cure to an elastomeric product in a controlled environment. These materials are typically packaged in rolls and adhered to the substrate using a thin layer of wet sealant on each side of the material.

Silicone pre-cured joint sealants are most commonly used in construction applications for several reasons, including:

  • Resistance to ultraviolet light and weathering.
  • Thin (1 to 2 millimeter) material minimizes bond forces and creates a flat profile.
  • Movement capability (up to +200 percent/-75 percent) is significantly higher than liquid sealants.

Over the past decade, pre-cured silicone sealants have been used in the construction industry for renovation applications, including repair of failed standard sealant joints. In this application, there is no need to remove the old sealant. Installation is easy: The pre-cured sealant is simply applied over the old joint, using a thin layer of silicone sealant adhesive on each side of the pre-cured sealant. This system saves time and reduces overall project costs. Pre-cured silicone sealant is especially useful on soft substrates, such as EIFS, where removal of the old sealant will damage the substrate and ruin the integrity of the joint.

Pre-cured sealants are commonly used in butt joint applications where the joint depth is not adequate for standard sealants to achieve an effective bond. This commonly occurs in leaking aluminum window systems.

Undersized joints are another ideal application for pre-cured silicone sealants. Undersized joints are commonly found in buildings lacking an adequate number of expansion joints, as well as window openings that do not have adequate space for a working perimeter joint. Because the adhesive is only used on the edges, the pre-cured silicone sealant system creates its own artificial joint to handle the movement in these scenarios.

Besides the applications already discussed, pre-cured silicone sealants are used in many other applications, including:

  • Roofing seals and parapet caps.
  • Curtainwall joints.
  • Skylights.
  • Interior window seals.

The unique product features and design capabilities of pre-cured silicone sealants make them ideally suited for many applications.

As pre-cured silicone sealants have become more popular, manufacturers have improved and expanded their product lines. Pre-cured silicone sealants are now available in many standard sizes and colors. Manufacturers also offer custom color and custom design material to meet various application requirements. Custom materials can be produced with one or more notches in the extrusion. These notches allow the material to follow complex bends in applications such as building corners, parapet caps, and window mullions. Materials are also available with surface textures to match the appearance of EIFS and other substrates.

Jason Bakus is director of sales and marketing at Harbor Springs, MI-based Sealex Inc. (www.sealexinc.com).


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