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Application brief 02

Retrofitting over an existing cast-in collar.

Can Fendix be installed over an existing cast-in?

Yes. RTL FA 2981.03 covers PVC-U configurations over functional, non-functional and unknown existing cast-ins. The complete configuration must be confirmed against the report.

See the site examples
Examples shown
4 case studies
Existing collars
Non-rated, stack + unknown cast-ins
Services
Stack + floor waste
Key issue
Unverified cast-ins + tight space

Real installations

Four completed Fendix rectifications.

Floor waste installed through an existing stack cast-in collar before rectification Before
Blue Fendix Collar installed over the existing stack cast-in collar as the floor-waste rectification After · Fendix installed
Installation 01Floor waste

Floor waste incorrectly installed through a stack cast-in, rectified with Fendix.

A floor waste had been installed through a cast-in intended for a stack. Fendix was fitted over the existing collar to rectify the issue and make the penetration compliant.

What was rectified

The existing cast-in collar was intended for a stack application, while the installed service was a floor waste. Fendix provided the compliant retrofit solution over the existing collar for a configuration confirmed against RTL FA 2981.03.

Fendix Collar installed around a 100 mm PVC-U stack beside a wall over a non-fire-rated deck collar
Completed installation
Installation 02100 mm stack

Non-fire-rated cast-in/deck collar or void former.

A 100 mm stack passed through a non-fire-rated deck collar or void former. The wall beside the penetration left little room for a conventional circular collar.

Why the installation fits

The slimline body fixes from the accessible side and works around the wall-side condition, without needing the collar to fully encircle the pipe.

Blue Fendix Collar installed beneath an existing Cougar cast-in collar around a PVC-U floor waste below a concrete slab
Completed retrofit
Installation 03Floor waste

Fendix installed beneath an existing Cougar cast-in collar.

The available evidence for this site did not confirm that the existing cast-in collar covered the exact floor-waste configuration. The collar remained in place, with Fendix installed directly beneath it as the compliant fire-stopping solution for a configuration confirmed against RTL FA 2981.03.

Why Fendix was used

Fendix becomes the fire-stopping device beneath the existing cast-in, avoiding pipework reconfiguration or a bulky fire-rated bulkhead.

Blue Fendix fire collar retrofitted beneath a damaged cast-in collar intended for a stack pipe, with a floor waste passing through it
Completed Fendix retrofit
Installation 04Floor waste

Incorrect cast-in collar, with damage.

This floor-waste installation had two issues:

  1. Incorrect collar type. The existing cast-in collar was intended for a stack pipe, but a floor waste had been installed through it.
  2. Damaged collar. The existing cast-in collar was also damaged.

Fendix was retrofitted beneath the existing cast-in collar, with the floor-waste pipework retained.

Assessment note

Confirm the complete pipe, slab, fitting and FRL configuration against RTL FA 2981.03 before installation.

View Test Report PDF

Quick answers

Questions installers actually ask.

Can it go over any existing cast-in collar?

Yes. The report covers existing cast-in collars that are functional, non-functional or of unknown function.

Does it cover both stacks and floor wastes?

Yes. Fendix covers both stack and floor-waste configurations across 50, 65, 80 and 100 mm PVC-U pipe sizes.

What if a wall or obstruction leaves very little room?

The 20 mm-thick profile, open U-shaped form and 15 mm-wide arms help Fendix fit beside walls, beams and other obstructions, provided the complete configuration is confirmed against RTL FA 2981.03.

Have an existing cast-in?

Send a site photo.

Send the penetration to Fendix and we will review whether the existing cast-in retrofit pathway may fit your project.

  • One clear photo from the underside of the slab
  • Pipe size and whether it is a stack or floor waste
  • Required FRL, quantity and postcode if known

A photo check helps identify the likely pathway. Final suitability still needs to be confirmed against the complete configuration in RTL FA 2981.03.

Prefer to talk? Call (03) 9115 1449

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