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SPAX Boundary Joist & Post Fixing Solution

The SPAX boundary joist solution provides an extremely fast, strong and reliable method of fixing deck boundary joists to decking joists and noggings, as well as fixing posts to boundary joists, without the use of brackets, coach screws, straps or bolts.

The SPAX solution is simple to install using fully threaded screws to achieve a very strong connection. Testing was conducted in New Zealand and results fulfil the strength and deflection requirements of NZS 3604, AS/NZS 1170, and clause B1 of the New Zealand Building Code.

Key Features
  • At least 3 times faster than traditional methods providing a saving in labour costs
  • Easier to use and more aesthetically appealing than using brackets, straps, bolts or coach screws
  • Manufactured from A4/316 stainless steel for exceptional durability and Building Code compliance
  • Cut point and serrated threads for quick start and low-torque installation
  • Drilling template available to ensure correct installation angle
  • PS1 Producer Statement available for Building Consent Authorities
Scope of Use

Clause of NZS 3604 states that “Where the deck or balcony is to support a cantilever balustrade, boundary edge joists shall be provided”. The SPAX boundary joist solution is used in this situation to attach a double boundary joist to the end of deck joists. The same solution is used to attach the inner end of noggings. 

  • Can be used for joist sizes 190 x 45 or 240 x 45
  • Specifications available for face-fixed and top-fixed posts
  • Applies to timber of grade SG8 or better

The SPAX post fixing solution is used for fixing the cantilever balustrade to the boundary joist.

  • Used for both face-fixed and top-fixed posts
  • Maximum post spacing provided on the installation instructions
Limitations on Use
  • Must be designed and installed in accordance with the SPAX Boundary Joists Technical Brochure PS1 2020 document
Statement of Building Code Compliance

The SPAX Boundary Joist & Post Fixing Solution meets the requirements of:

  • Clause B1 of the New Zealand Building Code
  • New Zealand standard NZS 3604
  • Strength and deflection requirements of AS/NZS 1170
Boundary Joists Technical Brochure PS1


SPAX is a German manufacturer of quality, innovative screws for timber connections such as framing, timber construction, decking, flooring, and cladding.

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