Sealant backing and bond breakers establish sealant depth and prevent detrimental three sided adhesion. Properly installed sealant backing prevents sealant leakage and creates a proper sealant profile. Sealant backing function ceases once sealant is applied, tooled, and cured.
- A joint filler is inserted into joints that are deeper than required for the sealant backing and sealant installation.
- For moving joints the joint filler and sealant backing must be compressible.
- Sealant backing provides resistance to sealant tooling pressure and helps to attain proper wetting of the substrate when sealant is tooled.
Recommended Backing Materials
- Closed cell sealant backing: primarily a polyethylene foam with a surface skin.
- Vertical and horizontal joints with one or two component sealants. Approved for use in EIFS applications.
- Closed cell sealant backing must be no more than 25%-33% larger than joint width so it remains in compression and in place during sealant installation.
- Do not rupture the skin of closed cell sealant backing material during installation, this can cause air bubbles in the sealant compromising its ability to perform.
- Open cell sealant backing: primarily a urethane foam without a skin.
- Vertical joints utilizing one-component sealants when cure speed is critical.
- Double caulk beads in vertical joints for curing of initial (internal) caulk bead.
- Must be at least 25% larger than joint width so it remains in compression and in place during sealant installation. Not for use in horizontal traffic joints or EIFS applications.
- Bi-cellular sealant backing: composed of both open and closed cell polyethylene or polyolefin foam with a surface skin. Recommended for all sealant applications with the exception of applications requiring rapid curing from backside.
- Bond breaker tape: primarily a self-adhesive polyethylene or teflon material.
Not Recommended for Backing Material
- A rigid joint filler or sealant backing in joints that will experience movement.
- Using braided sealant backing to compensate for a joint opening that is too large for the backing material.
Recommended Backing Materials
- Closed cell sealant backing: primarily a polyethylene foam with a surface skin.
- Vertical and horizontal joints with one or two component sealants. Approved for use in EIFS applications.
- Closed cell sealant backing must be nomore than 25%-33% larger than joint width so it remains in compression and in place during sealant installation.
- Do not rupture the skin of closed cell sealant backing material during installation, this can cause air bubbles in the sealant compromising its ability to perform.
- Open cell sealant backing: primarily a urethane foam without a skin.
- Vertical joints utilizing one-component sealants when cure speed is critical.
- Double caulk beads in vertical joints for curing of initial (internal) caulk bead.
- Must be at least 25% larger than joint width so it remains in compression and in place during sealant installation. Not for use in horizontal traffic joints or EIFS applications.
Refer to Pecora Technical Bulletin #106 Backer Rod Use for more information.
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