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JOINTFLEX® BACKER ROD Closed Cell Polyethylene Filler


JOINTFLEX® BACKER ROD Closed Cell Polyethylene Filler

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Product Description

CORKJOINT JOINTFLEX® BACKER ROD Closed Cell Polyethylene Filler are manufactured from closed cell polyethylene, are non-absorbing, are U.V resistant and have excellent weatherability properties. It is a type of material that is commonly used in construction projects as a backing material for sealing joints, gaps, and cracks in various surfaces. It is particularly useful in applications where a flexible, compressible material is needed to create a watertight seal.


  • Non-absorbent
  • Excellent weatherability
  • No bitumen contents
  • Acts as a bond breaker
  • Lightweight
  • Resistant to ultraviolet light
  • Ability to compress and recover
  • Suitable for submerged or trafficable joints

Areas of Application

Jointflex® Backer Rod are used in joints in pre-cast and cast-in-situ concrete elements to give support to the joint sealant application, aid in the correct joint sealant geometry (application depth and shape) and prevent the joint sealant from adhering to the top of the expansion joint filler board (3-way bonding), acting as a bond breaker. 

Note : The product’s design and performance, its intended use, installation and final confirmation and approval for use, must be provided by the project’s Design Engineer and Project Manager

Available Sizes

Jointflex® Backer Rod are available in roll lengths for round shapes and available in lengths of 1 metre, 1.5
metre and 2 metre for square sections. Standard diameter sizes are 6mm up to 80mm. Section sizes are as follows: 10mm x 10mm, 15mm x 15mm, 20mm x 20mm and 25mm x 25mm. Custom diameter and section sizes can be easily manufactured to suit.

Physical Properties

Note: The above physical properties are test results from an in-house laboratory test report. Material properties can vary between batches of ± 10%. Project specific material properties can be custom produced to suit.

Choice of Selection


Typical Applications


Typical Installations

Choose a diameter or square section which is approximately 20% to 25% bigger than the actual joint size so it can be compressed to fit inside the joint, creating a tight and firm fit. Apply the backer rod to your specified depth for the sealant application.

Written Specification

Where shown in the Brochure drawings, the backer rod filler material shall be Jointflex® Backer Rod closed cell polyethylene filler material with a minimum density of 25kg/m³, as supplied by CORKJOINT. The application / installation of the product must be in accordance with the manufacturer’s recommendations.

Health and Safety Information

In confined spaces or in still air conditions, the use of a ventilation fan or suitable respirator should be used, and the advice and approval of the Site Safety Supervisor is essential. For further information or advice on health and safety precautions, safe handling, storage and correct disposal of products, please refer to the most recent product Safety Data Sheet (SDS), which is available upon request


The information and the recommendations relating to the application and end use of this product are given in good faith and are based on the information provided by the manufacturer of the product and/or the Company’s current knowledge and experience in connection with the product when properly stored, handled and applied under normal conditions and no liability of final function at the job site is assumed. In practice, the differences in materials, substrates and actual site conditions are such that no warranty in respect of merchantability of, or fitness for, particular purpose, nor any liability arising out of any legal relationship whatsoever, can be inferred either from this information, or from any written and/or oral recommendations, or from any other advice offered by the Company. The Company also has no express or implied knowledge of any particular purpose for which the product is required and any such information given will not be taken into account in the supply of this product. No responsibility or liability by the Company will be accepted for misuse, misreading or derivation from recommended guidelines in respect of this product and the user shall determine the suitability of the product for his intended use and assume all risks and liability in connection therewith. The information contained in our brochure may change at any time without notice. Any use of this product, JOINTFLEX® BACKER ROD Closed Cell Polyethylene Filler, in any application should be approved as suitable for use/application by the Design Engineer and Project Manager.