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UNI PLUS Flexible Air Barrier

UNI PLUS Flexible Air Barrier is a fire retardant flexible wall underlay giving early enclosure to builds, allowing work to continue on the inside (for up to 90 days), without waiting for the cladding to be complete.

UNI® PLUS assists in the control of moisture by ensuring moisture, which occasionally penetrates the wall cladding, does not penetrate into the wall cavity and is diverted to the back of the cladding as well as being shed via the cavity. During construction UNI PLUS also functions as temporary weather protection allowing internal works to continue without the cladding in place for up to 90 days.

Key Features
  • Eliminates expensive delays due to hold-ups on cladding or bad weather 
  • Once installed, UNI PLUS works as a secondary line of defence against moisture over the life of the building, whilst still being highly breathable, passing vapour from the inside of the building out.
  • A fraction of the cost of rigid air barriers (materials and labour) whilst having most of the benefits
  • UNI PLUS has fire retardant qualities
  • UNI PLUS is much thicker and stronger than standard building paper/wrap 
  • Quick and easy installation

Physical Attributes

  • UNI PLUS is a non-woven, absorbent, vapour-permeable, water-resistant, fire-retardant, 180 GSM synthetic wall underlay.
  • It comprises three polypropylene layers: two outer layers of non-woven polypropylene with a middle layer of a functional-technical film
  • It meets New Zealand Standard NZS 2295:2006 characteristics as stated in Table 23 of Acceptable Solution E2/AS1
  • It is supplied in 2.74m x 18.25m rolls (50 m²) coloured blue with a white underside unless an alternative colour is requested
NZ-Owned Business
NZ-Owned Business
Scope of Use

UNI® PLUS is a fire retardant flexible wall underlay, with the following suitability:


  • In locations with a wind design pressure (ULS) of up to and including 4.6 kPa (which includes all NZS 3604:2011 wind zones).
  • For 'Very High' wind zones over rigid wall underlays
  • In seismic zones up to and including seismic zone 3
  • In all exposure zones
  • Further than 1 m from a relevant boundary


  • For commercial and residential construction
  • Designed for use with all cladding systems
  • Performs on timber and steel framed buildings
  • As a temporary cladding for up to 90 days
  • With buildings of all building heights, up to the permissible wind design pressure of 4.6 kPa
  • With cladding and joinery that complies with the relevant provisions of the NZ Building Code for the site and location
  • Suitable for use as a non-rigid backing for stucco plaster
  • UNI® PLUS is suitable as an air barrier on walls that are not lined
  • For vertical use only, not suitable as a roof underlay
  • UNI® PLUS Must be covered with a suitable wall lining to any occupied spacings
Limitations on Use
  • UNI PLUS (or any flexible air barrier) cannot provide seismic (bracing or racking), and fire-resistance
  • For lightweight steel, a thermal wrap must be installed
  • Where a building height is greater than 10 m and upper levels contain sleeping uses or other property the external wall must be subject to specific fire engineering
  • In occupied spaces, UNI PLUS must always be installed in conjunction with an internal lining
  • UNI® PLUS must be covered within 90 days from installation
NZS 3604 Wind Zone Very High suitable
Very High WInd Zone
Statement of Building Code Compliance


  • UNI PLUS meets or exceeds the requirements of the NZBC
  • Product Assurance Supplier Statement; PASS. Documentation is available from the downloads button on this page

If designed, installed and maintained in accordance with all Masons Plastabrick’s requirements, UNI PLUS will comply with or contribute to compliance with the following performance claims:  

B1 STRUCTURE: B1.3.1, B1.3.2, B1.3.3 (a, e, f, h, j, m, q, & UV), B1.3.4 (a, b, c, d, e)

  • Meets requirements of NZS 2295:2006; tested to ASTM D882 for tensile properties, TAPPI T470 for resistance to tearing. NZS 2295:2006 is referenced in E2/AS1 for flexible underlays [Scion, 01/2022].

B2 DURABILITYB2.3.1 (a), B2.3.2 (b)

  • Meets requirements of NZS 2295:2006; tested to ASTM G154 for accelerated UV ageing [Scion, 01/2022].


  • Meets requirements of NZS 2295:2006; flammability index of 1 when tested to AS 1530.2:1993 [NZWTA, 01/06/2021].

E2 EXTERNAL MOISTURE: E2.3.2, E2.3.5, E2.3.7 (a, b, c)

  • Meets requirements of NZS 2295:2006; tested to AS/NZS 4201.4 for water penetration, tested to AS/NZS 4201.6 for surface water absorbency, tested to ASTM E96 Procedure B for Water vapour resistance [Scion, 01/2022].
  • Installation details and requirements in accordance with E2/AS1.


  • Manufactured to EN 13859-2:2014; product does not emit harmful materials based on supplier’s technical data and testing specification and material safety information [Masons Plastabrick, 30/08/2021a, 30/08/2021b].
  • Use in accordance with the supplier’s requirements [Masons Plastabrick, 01/2022].
In-Service History

Masons Building Products has been in the industry for over 20 years. Customer satisfaction is paramount. A dedicated team of Masons Representatives cover NZ nationwide to assist and instruct customers in using Masons products. 

Other Performance Attributes


Masons UNI PRO is to be installed with the correct components: 

Collectively these products complete the weather-tightness of the building membrane. 

General Installation Instructions:

  • Fix with the printed side out
  • Run the wrap horizontally
  • Pull taut over the framing before fixing
  • Only to be fixed with Masons UNI Fasteners either with a gun or hammer. Staples must not be used.
  • For timber frames: use 32mm Nail/washer. For steel frames: use UNI washers with either a Phillips or square drive self-drilling screw.
  • Be lapped, not less than 75mm at horizontal joints; Have upper sheets lapped over lower sheets to ensure that direction of laps will allow water to be shed to outside of the wall underlay
  • Be lapped, not less than 150mm over studs at vertical joints 
  • Extend 50mm below bottom plate or bearer

UNI PLUS must be installed by a Licensed Building Practitioner using Mason's full installation instructions.

These instructions are available as a video or a printed version in the downloads button of this page. Training on-site can also be arranged via a Masons Rep.

Storage and Handling

Masons UNI PLUS, whether on or off-site should:

  • Be stored on end under a cover, in a clean and dry area 
  • Protect the rolls from crushing or damage
  • When fixing the product in windy conditions, care must be taken due to the large sail area created by wide roll widths
Data Sheet
Specification Clause/Guide
PASS Statement
Installation and Operation
Installation Instructions in Chinese
Onsite Checklist
Maintenance and Warranty
Take off sheet

Since being established in 1999, Masons has become a key supplier in the New Zealand building industry, offering a variety of quality products and tools for a whole range of building requirements.

Product Enquiries

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