40mm Flat Back Flashing RDFB40

Back Flashings (or Flat Back Soakers) are designed to provide a second line of defense behind a vertical control joint to prevent moisture from entering the cavity due to the shrinking of the cladding boards.

  • Category
    Flashing Penetrations
  • Range
    Internal Flashings

Redway uPVC Back Flashings are available in 3 sizes (40mm, 135mm, and 160mm) with all profiles supplied in 2.7m lengths.

Each Back Flashing should be installed vertically behind the cladding joint.

Internal Flashings

Internal flashings to deflect & drain moisture at key joints & penetrations.

While leaks primarily occur around windows and doors, they also occur at other joints and penetrations of the cladding and trim. The NZBC, therefore, requires flashings to be installed in order to ensure weather tightness and maintain the overall health of the building.  Internal flashings provide a moisture barrier and drainage plane that prevent moisture build-up and deflect moisture to the building exterior.  All Redway Internal flashings are manufactured from corrosion-resistant, UV-protected uPVC, and are available from all leading building merchants.


  • All Internal Flashings are manufactured from rigid uPVC and are supplied in 2.7m lengths unless stated otherwise.
  • All products are biologically and chemically resistant to treated materials such as framing timber. They will not rust nor react in salt zones.
  • The uPVC compound is stabilised for UV protection as required by the NZBC.
  • It is lightweight allowing for easy transportation and installation.
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Masons provide a range of quality trade building products from a complete Enclosure Building Wrap System and Exterior Cladding, to Brick Reinforcement, and are a crucial supplier in the New Zealand building industry.

Masons strive to be at the forefront of developing innovative products that raise the standards of New Zealand building products.