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The Main Function and Varying Options of Backer Rods

June 04, 2018

Known by many names like a backer foam or a pre-caulking filler rope, a backer rod functions the same and can be incredibly useful in many applications. It is primarily used as material for construction application and joints that require sealants, often in doors, hinges, screens and the like.


A backer rod serves as depth control for cold applied sealants which will not adhere and does not require a bond breaker. As such, it prevent three-sided adhesion and is perfect to create the best joint designs such as an hourglass shape sometimes necessary for proper joining.


Using a backer rod saves you money since it fills the joint by using less caulking material. With the ideal joint design, a backer foam allows caulks to stretch better and properly prevents a rip or tear. 


Filler rope comes in two basic types: closed-cell and open-cell. The closed-cell backer rods are most suited to fill joints which are prone to moisture prior to sealing such as horizontal joints. They are also available in different variants. Standard backer rods are suitable for the following applications:


??        Glazing installations

??        Expansion joints

??        Curtain wall joints

??        Door and window applications

??        Log construction

??        Partitions

??        Pavement jobs

??        Precast units and copings


Whenever standard backer rods are not appropriate or insufficient, soft backer rods are a solid alternative. They are great for irregular joint designs, especially where free flowing or self-leveling sealants are employed. However, an open-cell backer rod is designed for use with sealant materials that are moisture cured. It is typically considered slow-curing, low-modulus yet high performance silicone sealants. Though both closed-cell and open-cell backer rods are useful in cold temperatures, the latter works better in extremely cold environment. 


When installing a backer rod, joints or openings should be dry and free of all contaminants, frost or loose materials. It is very important to choose the right size of backer foam that matches the joint width and its depth has to be consistent with the recommendation of the sealant manufacturer using a proper tool.


Alcot Plastics Ltd. is the leader in manufacturing closed-cell extruded polyethylene foam products for a wide variety of applications. Contact us today to learn more or to request a confirmation.