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UNI Flexible Air Barrier

UNI Flexible Air Barrier is a 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.

Once the cladding is in place, UNI becomes a secondary line of defense against moisture by ensuring moisture that occasionally penetrates the wall cladding is directed back to the exterior of the building.

Key Features
  • Eliminates expensive delays due to hold-ups on cladding or bad weather 
  • Once installed, UNI 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
  • Much thicker and stronger than standard building paper/wrap 
  • Quick and easy installation
NZ-Owned Business
NZ-Owned Business
Scope of Use


  • In locations with a wind design pressure (ULS) of up to and including 4.6 kPa (which includes all NZS 3604:2011 wind zones)
  • UNI is suitable 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 1m 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 is suitable as an air barrier on walls that are not lined
  • For vertical use only, not suitable as a roof underlay
  • UNI must be covered with a suitable wall lining to any occupied spacings
Limitations on Use
  • UNI (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 10m and upper levels contain sleeping uses or other property the external wall must be subject to specific fire engineering
  • In occupied spaces, UNI FAB must always be installed in conjunction with an internal lining
  • UNI must be covered within 90 days from installation
NZS 3604 Wind Zone Very High suitable
Very High WInd Zone
Statement of Building Code Compliance

New Zealand Building Code standard (NZBC)

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

If designed, installed and maintained in accordance with all Masons Plastabrick’s requirements, the UNI® FAB 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)

  • Manufactured to EN 13859-2:2014; tested to EN 12311.2:2013 for tensile properties, EN 12310.1:2010 for resistance to tearing, EN 1107.2:2002 for dimensional stability based on supplier’s technical data and testing specification [Masons Plastabrick, 30/08/2021b]. 

B2 DURABILITY: B2.3.1 (a), B2.3.2 (b)

  • Manufactured to EN 13859-2:2014; tested to EN 1297 & EN 1296 for UV exposure and UV exposed samples tested to EN 12311.2:2013 for tensile properties, EN 12310.1:2010 for resistance to tearing, EN 1924.2002 for resistance to water penetration based on supplier’s technical data and testing specification [Masons Plastabrick, 30/08/2021b].


  • Manufactured to EN 13859-2:2014; tested to EN ISO 11925-2/ AC:2011 for reaction to fire based on supplier’s technical data and testing specification [Masons Plastabrick, 30/08/2021b]. 

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

  • Manufactured to EN 13859-2:2014; tested to EN 1928:2002 for resistance to water penetration, EN ISO 12572:2004 for water vapour transmission properties, EN 12114 for air resistance based on supplier’s technical data and testing specification [Masons Plastabrick, 30/08/2021b].
  • Tested to AS/NZS 4201: Part 6 for absorbency [Scion, 02/2020].
  • Installation details and requirements meet E2/AS1, E2/AS4.


  • 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].
In-Service History

Masons Plastabrick Ltd is NZ owned and operated and has been in business since 1999. All Masons products have warranties. Customers are supported 100% by the Masons team of Nationwide experts who travel the country to support their customers.

Other Performance Attributes

Physical Attributes:

  • UNI is a nonwoven, absorbent, water-resistant 180 GSM, synthetic wall underlay.
  • UNI is water-resistant and designed to provide temporary protection from weather conditions and UV exposure to timber framing, without the installation of the cladding, which allows for the continuation of internal work on the build for 90 days after installation. 
  • UNI comprises three polypropylene layers: two outer layers of non-woven polypropylene with a middle layer of a functional-technical film. It is manufactured to meet the European standard EN 13589-1:2014 as well as the absorbency performance requirement as per NZS 2295:2006.
Independent Assessment
Independent Assessment
Test Results
Test Results
E2 External Moisture compliant
External Moisture
Design and Installation Guide

V1.0 Sept 21

Technical Data Sheet

V1.0 Sept 2021

Material Safety Data Sheet

V1.0 Sept 2021

PASS: UNI Flexible Air Barrier

no. 19154

Specification Guide

V1.0 Sept 2021

CodeMark CM70116

CM70116 Rev1

UNI Flexible Air Barrier Installation Instructions - Simplified Chinese
UNI Installation Guide
Maintenance and Warranty
CAD/PDF Details
UNI Flexible Air Barrier Drawings

Nov 2021

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.

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