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A heavy-duty flexible wall underlay that gives early enclosure to builds, allowing work to continue on the inside (for up to 150 days), without waiting for the cladding to be complete.

Key Benefits
  • Helps keep construction moving. Once installed it allows the continuation of internal work on the build, without cladding in place for up to 150 days after installation. 

  • Once installed, UNI PRO is a secondary line of defence against moisture over the life of the building.

  • 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.

  • 22% thicker than UNI and much thicker and stronger than standard building paper/wrap. 

  • Quick and easy installation with many resources to assist first-time users.

  • Codemark Certified.

Physical Attributes
  • A non-woven, absorbent, water-resistant, synthetic wall underlay.

  • Comprised three polypropylene layers: two outer layers of non-woven polypropylene with a middle layer of a functional-technical film.

  • Has a blue front face and a white rear face - and a middle membrane which is dark grey. Both sides of the sheet have a fine embossing pattern. The sheet is 2.74 metres wide and marked UNI PRO Flexible Air Barrier.

Scope of Use

Masons UNI PRO Flexible Air Barrier is certified for use as a wall underlay and air barrier on buildings:

a) within the scope limitations of:

i. NZBC Acceptable Solution E2/AS1, Paragraph 1.1 with regards to building height and floor plan area for timber-framed construction; or
ii. NZBC Acceptable Solution E2/AS4 with regards to building height and floor plan area for light-steel framed construction, and

b) situated in wind zones (as defined in NZS 3604:2011) up to and including ‘Extra High’, provided stud and fixing centres are no greater than specified in the Masons UNI® PRO Flexible Air Barrier Design and Installation Guide V1.0, November 2021, and

c) with absorbent or non-absorbent wall claddings directly fixed to the frame, or installed over an 18mm minimum drained cavity; or with masonry veneer, in accordance with NZBC Acceptable Solution E2/AS1 for timber-framed buildings or NZBC Acceptable Solution E2/AS4 for steel-framed buildings, and

d) where the underlay is not exposed to view in an occupied space.

Masons UNI PRO Flexible Air Barrier shall be:

a) installed in accordance with the MASONS UNI® PRO Flexible Air Barrier Design and Installation Guide V1.0, November 2021, and

b) separated from fireplaces, heating appliances, flues and chimneys in accordance with the requirements of NZBC Acceptable Solutions C/AS1 and C/AS2, Paragraph 7.5.9 for the protection of combustible materials, and

c) protected from sunlight within 150 days

Contribution to compliance with Building Code clause H1.3.1(b) is conditional on

a) the element incorporating UNI PRO Flexible Air Barrier being part of the thermal envelope of the building, and

b) horizontal and vertical laps being securely taped.

Scope of Use: Building and Location


  • In locations with a wind design pressure (ULS) of up to and including 4.6 kPa (which includes all NZS 3604:2011 wind zones).

  • 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.

  • 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 of 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 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 must always be installed in conjunction with an internal lining.

  • UNI must be covered within 90 days from installation.

NZ Building Code Standard (NZBC)

UNI PRO meets or exceeds the requirements of the NZBC. For details, please visit the MBIE website to view the Codemark

Product Assurance Supplier Statement; PASS. Documentation is available from the downloads button on this page.

Storage and Handling

Masons UNI PRO, whether on or off-site should be stored on end and under a cover, in a clean, dry area. Protect the rolls from crushing or damage.

Take care when fixing the product in windy conditions, due to the large sail area created by wide roll widths.

General Installation Notes

UNI Flexible Air Barrier must be installed by a Licensed Building Practitioner using Mason's full installation instructions available as a video or a printed version on this page. On-site training can also be arranged if appropriate through your Masons Rep.

  • Fix with the printed side out.

  • Run the wrap horizontally and pull it taut over the framing before fixing

  • Only to be fixed with Mason's UNI Fasteners either with a gun or hammer. Staples must not be used.

  • For timber frames: use a 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 the bottom plate or bearer

Masons UNI PRO Installation Video

12 min 30 sec viewing time


What is UNI?

UNI PRO is a heavy 3 ply polypropylene flexible air barrier. UNI PRO is highly resistant to air and liquid water whilst allowing water vapour to pass. UNI PRO is the thickest of our UNI family of Flexible Air Barriers and is substantially thicker than conventional flexible wall underlay and is very tough and strong. It is UV resistant for up to 150 days.

When assembled using specific components and according to designated system UNI, UNI PLUS and UNI PRO may be used as Flexible Air Barrier as a temporary weather protection allowing interior works to continue without cladding in place for 90- 150 days. UNI, UNI PLUS & UNI PRO carry Codemark certificates of conformity.

Is UNI PRO fire retardant?

No, UNI PRO is not fire-retardant. UNI PLUS is our fire retardant product.

Can UNI PRO be exposed longer than 150 days?

Ideally not. Very short over exposure – contact Masons for advice. Substantial over exposure will require an over-wrap or re-wrap in most cases.

Can I fix UNI PRO with staples or cap staples?

No, only cap nails or nailed battens may be used to fix UNI PRO to timber frames, there cap screws for fixing to Steel frames. Staples may be used inside the joinery opening and above the soffit framing line.

Does a soffit roll have to be used?

No this is an optional part or the system, this is up the builder if they wish to use it to suit their build.

Can any brand of flashing tape be used?

Only 40 Below Platinum or Flex have been tested and incorporated into the Codemark

Do all seams and over laps need to be sealed?

Yes – flash all overlaps with 40 Below Platinum or Flex 75mm

Flashing tape all around the joinery opening?

Flash the sill and 200 mm up the jamb, flash the Head and Jamb 200 x 200 mm per Masons 40 Below Platinum or Flex, or UNI installation instructions.

What are the cap nail fixing intervals?

These vary with the stud spacing & the wind zones- check the Masons UNI, UNI PLUS and UNI PRO installation instructions FIXING CHART for details.

Does wrap strap (Dan Band) need to be used on UNI?

For 600 mm studs with a 18-25 mm drained cavity YES to avoid the possibility of UNI billowing into the cavity if the insulation is over pressed in.

What about for 600 mm studs and Brick veneer?

If UNI, UNI PLUS or UNI PRO is pulled TIGHT across the studs wrap strap should not be necessary. Some BCAs will insist on wrap strap being fitted over UNI as this is stated in E2/AS1. Over-vigorous fitting of insulation may cause billowing.

What about for other stud spacings?

If UNI, UNI PLUS or UNI PRO is pulled and fitted TIGHT across the studs there should be no issue.

Does UNI PRO need to be stuck to the slab?

No, simply drape UNI, UNI PLUS or UNI PRO 50 mm below the bottom plate until the cladding is in place

Can UNI PRO be used in an EXTRA HIGH wind zone?

Yes with limitations. Studs and fixings need to be at stated intervals, and additional installation requirements apply per the Masons installation instructions. If the job is multi storey or complex Masons Barricade Weather Defense rigid wall underlay system may be a more suitable choice.

Can I use any kind of batten?

Continuous timber or castellated battens may be used. Fastened per Masons installation instructions – UNI FIXING CHART.  James Hardie CLD battens (TM) may also be used for vertical batten applications. These must be fitted strictly in accordance with James Hardie installation instructions including fixings and intervals for CLD Battens (TM) NOT per the UNI Installation instructions UNI fixing chart.

Other types of battens have not been considered by Masons.

Must DPC flashing be used up the Jambs and a second layer of UNI be used over the head flashing on all jobs?

Additional flashing – weather deflectors and a second layer of UNI over the head flashing must be fitted for UNI or UNI plus used in Very High or Extra High wind zones. And for all wind zones when used for UNI PRO. Please see Masons UNI installation instructions and the Masons UNI & UNI PRO 10 min You Tube training videos. Masons recommends this method for all wind zones but is optional for UNI and UNI PLUS below Very High wind zones.

Do Masons penetration seals need to be used on all pipes and conduits?

Yes, every effort should be made to use Masons Penetration seals.

If these genuinely cannot be obtained, then any trade seal based on acrylic adhesive and either BRANZ appraised, or Code marked may be used. Penetrations with a difficult shape (like HIVAC ducts, or brackets for pergolas etc) may be flashed to the UNI with 40 Below Platinum or Flex working from the bottom of the penetration up the sides and finishing with the top – so water always runs off freely.

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