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Appraisal number: 774 (2019)

Date issued: 6 Sep 2019


The Warmup Wetroom System is for internal wet areas of buildings that are to be finished with ceramic or stone tiles. The system consists of Warmup Insulation Backer Board, ARDEX Undertile Sheet Membrane preformed shower trays and Warmup Undertile Heating.


The Warmup Wetroom System has been appraised for use in internal wet areas of buildings within the following scope: 

  • On floor substrates of concrete, plywood, compressed fibre-cement sheet and fibre-cement sheet tile underlay and on wall substrates of concrete, concrete masonry, wet area fibre-cement sheet lining systems and wet area plasterboard lining systems.
  • On structural floors and walls complying with the NZBC.
  • Where floors are designed and constructed such that deflections do not exceed 1/360th of the span.
  • Where floors are designed not to exceed a continuous operating temperature of 35°C.
  • When protected from physical damage by a screed and ceramic or stone tiles.

The use of the waterproofing membrane on concrete slabs where hydrostatic or vapour pressure is present from below is outside the scope of this Appraisal.

Movement and control joints in the substrate must be carried through the membrane to the screed, tile or stone finish. The design and construction of the substrate and the movement and control joints is specific to the building and is therefore the responsibility of the building designer and building constructor and is therefore outside the scope of this Appraisal.

The ceramic or stone tile finishes are outside of the scope of this Appraisal.

The system must be installed by trained installers approved by Warmup New Zealand Ltd.

Technical literature

Consenting instructions

Always refer to the Appraisal in full and the technical literature.

Appraisal holder

Warmup New Zealand Ltd
Phone: 09 820 4001

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