Repair Systems — 01
Backer Rod & Bond Breaker Tape
Technical product reference for closed-cell polyethylene foam backer rod and bond breaker tape used to control sealant depth, prevent three-sided adhesion and create correct sealant profile in movement joints on Australian balconies, podium decks and wet areas.
What are backer rod & bond breaker tape?
Backer rod is a closed-cell polyethylene foam cylinder installed in a movement joint before sealant. It does two jobs: controlling sealant depth (maintaining the correct depth-to-width ratio) and preventing three-sided adhesion — where the sealant bonds to both joint faces and the base at once and tears at the base under cyclic movement instead of stretching at the faces. Backer rod is closed-cell only; open-cell foam absorbs sealant and defeats the purpose, and the diameter should be ~25% larger than the joint width for a snug interference fit. Bond-breaker tape is a self-adhesive polyethylene film used instead of round rod in shallow, saw-cut and rebated joints where rod cannot seat, giving the same bond-breaking function at a flat base.
Product Reference
Individual products — one card each — scroll to view all
Nomaflex / Carpenter Co.
Nomaflex Closed-Cell Backer Rod
Closed-cell PE backer rod — round
Nomaflex is a closed-cell polyethylene foam backer rod that controls sealant depth and prevents three-sided adhesion in movement joints, installed by compressing into the joint before sealant. Select the diameter ~25% over the joint width and confirm range and compatibility with the supplier.
Tremco CPG Australia
Tremco Closed Cell Backer Rod
Closed-cell PE backer rod — round (Tremco systems)
Tremco CPG supplies a closed-cell polyethylene foam backer rod as an accessory within Tremco sealant systems to set joint geometry and prevent three-sided adhesion. Confirm the product designation and diameter range with Tremco CPG Australia.
Various — confirm with supplier
Polyethylene Bond Breaker Tape
Self-adhesive PE bond-breaker tape — flat
Polyethylene bond-breaker tape is a self-adhesive PE film applied to a flat joint base where round backer rod cannot seat — in shallow, saw-cut or rebated joints — so the sealant bonds to two faces only. It must be fully adhered with no voids; confirm a compatible tape with the sealant manufacturer.
Various — confirm with supplier
Open-Cell (Soft) Backer Rod
Open-cell PE/PU backer rod — round (specialist use)
Open-cell (soft) backer rod is a compressible rod sometimes used in irregular or variable-width joints where a soft rod seats better. Because open-cell foam can absorb sealant and moisture, it is a specialist option — use only where the sealant manufacturer specifically permits it, with closed-cell rod the default for wet-area joints.
System Comparison
Backer rod & bond breaker tape — confirm all selections against the current manufacturer TDS before specifying.
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Disclaimer
Information is general only. Backer rod and bond breaker tape selection must be confirmed against the sealant product specification, joint geometry, substrate conditions, and the current manufacturer technical data sheet. AS 3740 requires flexible sealant at all internal angles — correct joint preparation including backer rod is mandatory. Do not rely on this reference as a substitute for professional waterproofing consultant advice.