40 Below™ Flashing Tape is a self-adhesive flashing tape to seal around windows, doors, and other joinery openings as a secondary defence against water penetration.

This classic, white facer tape has excellent adhesion in a wide range of conditions. It is great value for money and with a no-nonsense performance record, earns the trust of the professionals. 40 Below is compatible with most wraps and sealants so eliminates issues on site.

NB. Masons 40 Below Flashing Tape and Masons Corner Guards must be installed in accordance with the installation instructions.

Application

  • Incredible adhesion in all conditions.
  • Simple 4 step installation. Save time reducing costs.
  • Reliable and dependable weather tightness.
  • An Optional Corner Guard is easy to install and increases protection to framing.
  • RIGID AIR BARRIERS – 40 Below is tested and approved for sealing the joints on Rigid Barriers. Tested and approved for use by BGC Durabarrier and OS’BraceRAP.
  • 2 layers are required on the sill for nail and screw sealability

New Zealand Building Code Standard (NZBC)

  • For a risk score between 0-20 in accordance with NZBC Acceptable Solution E2/AS1.
  • Passed NZS3604 Building Wind Zones up to and including ‘Extra High’.
  • Passes nail sealability to ASTM 1970-01 section 7.9.
  • New smooth white facer tape also passes screw sealability to AAMA 711-13.
  • 2 layers are required on the sill for nail and screw sealability

Physical Properties

  • Extremely thin only 0.2mm, allows for easier fitting of windows and doors.
  • Works in temperatures from -40°C up to 65°C.
  • Compatible with most building wraps.
  • Compatible with most building sealants – check suitability with sealant manufactures. Alternatively, do a patch test before use.

Technical Data

Windows/Door/Timber & Steel Frame Flashings

  • Masons 40Below™ Flashing Tape and Masons Corner Guards must be installed in accordance with these instructions. Ensure the 40 Below™ Tape completely covers the joinery opening.
  • To ensure maximum adhesion of the tape, make sure the substrate surface is clean, dry, and free from any dust or other contaminants. Flaps are folded into the opening and secured.
  • The building wrap is installed as shown to the exterior face of the frame. A window and door openings are cut at a 45˚ angle away from each corner, then the flaps are folded into the opening and secured.
  • 40Below™ Flashing Tape must not be stretched. When joining 2 sections of tape, overlap by 100mm or more.
  • Compatible with most building sealants, check suitability with sealant manufactures. Alternatively, do a patch test before use.

RIGID AIR BARRIERS – 40 Below™ is tested and approved for sealing the joints on Rigid Barriers. Tested and approved for use with BGC Durrabarrier and OS’BraceRAP.

Details
  • Category
    Waterproofing Sealants
  • Range
    Masons 40 Below Flashing Tape
Specifications

Scope of Use / Applications

Windows/Door/Timber & Steel Frame Flashings

  • Masons 40Below™ Flashing Tape and Masons Corner Guards must be installed in accordance with these instructions. Ensure the 40Below™ Tape completely covers the joinery opening.
  • To ensure maximum adhesion of the tape, make sure the substrate surface is clean, dry and free from any dust or other contaminants. Flaps are folded into the opening and secured.
  • The building wrap is installed as shown to the exterior face of the frame. At a window and door opening it is cut on a 45˚ angle away from each corner, then the flaps are folded into the opening and secured.
  • 40Below™ Flashing Tape must not be stretched. When joining 2 sections of tape, overlap by 100mm or more.
  • Compatible with most building sealants, check suitability with sealant manufactures. Alternatively, do a patch test before use.

RIGID AIR BARRIERS – 40Below™ is tested and approved for sealing the joints on Rigid Barriers. Tested and approved for use with BGC Durrabarrier and OS’BraceRAP.

For enquiries, complete the contact form below or call us on 0800 522 533.
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About the
Seller

We’re Masons – a New Zealand owned family business that’s been part of the building industry for more than 25 years. We develop products and systems that help buildings, and the people that make them, perform at their best.

Masons was built from practical experience. Trent Mason learned the trade in a bricklaying family, where doing the job properly mattered. When he moved to New Zealand at the age of 19, he brought that same mindset to the building site – always looking for better products and systems to make the job easier for the people around him.

That approach still motivates us. We focus on the complete building envelope and how each component interacts with the next. Wraps, air barriers, fixings, tapes, cladding elements – everything works better when it works as a system. Our goal is to reduce risk and remove guesswork so buildings perform the way they should.

Over the years we’ve become known as trusted problem-solvers – the people you call when you want something explained clearly, when you need to understand how components connect, or simply want confidence you’re making the right call.

We’re here to help make building smarter, simpler and more reliable – with great products, great systems and great people.

Masons. Delivering products and systems to build smarter.

Masons