Box Gutters Alert to Building and Plumbing Practitioner

Tuesday, 4 October 2016

Compliant box gutters require architects, designers, builders and plumbers to work together

Too often the VBA finds box gutters installed that aren't the right size, don't terminate correctly or have other problems that make them non-compliant; which some practitioners have not realised.

Box gutters that fail to comply with the Plumbing Regulations 2008 are regularly found by the VBA Inspection Service Team in its work under the VBA Pro-active inspection program.

In addition to finding non-compliant box gutters, the Inspection Service Team members have spoken to many plumbers and builders who are not aware of the requirements for installing this type of gutter.

Box gutters have been found that change direction, include side chutes, reduce in size, terminate onto soaker flashings, are undersized , have inadequate overflow provision, and at times, terminate into downpipe pops.
What the deemed-to-satisfy provisions for roof drainage require:

It is important that practitioners are aware of the standards for the installation of box gutters. They must:

  • Discharge through an appropriately sized sump or rain head.
  • Discharge at the downstream end without a change in direction (ie, not through side chute).
  • Have a minimum width of no less than 200mm for a domestic box gutter 300 mm for commercial.
  • Have a depth at the high end of not less than 75mm.
  • Have adequate overflow provision at all rain-heads and sumps.
  • Have a sole width that is not to be reduced towards the outlet without a proportional increase in depth.

The VBA urges architects, draftspersons and building practitioners to consult with the licensed plumbers and where unable, the relevant standards, to establish what is required to assure a compliant job for the finished product (ie, roof framing to be constructed correctly so the licensed plumber can install compliant plumbing work).
What can Practitioners do?

Plumbing practitioners can ensure that they are up-to-date on the requirements of installing box gutters in the AS/NZS 3500.3:2015 Plumbing and drainage, Part3: Stormwater drainage and SA HB 39:2015 Installation code for metal roof and wall cladding.

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