Welcome To Gutter Grip

Welcome To Gutter Grip Welcome To Gutter Grip


Protect your building against damage from overflowing gutters with Gutter Grip, a world patented gutter fixing system.   

Gutter Grip is a unique system that complies with the strict Australian Standards and satisfies the performance requirements of the Building, Plumbing and National Construction Codes. Gutter Grip can be used for new or replacement gutters

Downpipe & Eaves Gutter Drainage Systems

  • In order to comply with The Plumbing Code of Australia (PCA) the performance requirements for downpipe and eaves gutter need to be satisfied.
  • The Design and Installation of Roof Drainage Systems (Gutters and Downpipes) must meet the performance requirements to comply.
  • To meet the Performance Requirements gutters need to be installed with sufficient downpipes to collect and dispose of water resulting from a storm having an Average Recurrence Interval (ARI) of 20 years.
  • Gutters are required to be installed using an overflow method that will avoid water entry into the building from a storm having an average recurrence interval (ARI) of 100 years.
  • Roof drainage systems need to be designed and constructed in a manner that the gutter and downpipe collect and convey water away from the building from a storm event of 1 in 20 year also when a storm event greater than 20 year and up to 1 in 100 year, the water when it overflows will not overtop the fascia and enter the building.
  • The Standard AS/NZS 3500 Part 3 Stormwater Drainage and Part 5 Domestic Installation shows methods to design a Roof Drainage System and show examples of acceptable overflow methods.
  • These examples of overflow methods if used, are compliant and foolproof, not requiring any special knowledge or expertise to design and construct a compliant Roof Drainage System.
  • The SAA/SNZ HB114:1998 Handbook “Guidelines for the Design of Eaves and Box Gutters” contains the same design method and examples of overflows that are shown in AS/NZS 3500.5 Domestic Installations.
  • The NSW Government Fair Trading website has a Roof Drainage Systems guide which uses the same design methodology and shows the same examples of overflows that are shown in AS/NZS 3500.5 Domestic Installations.
  • The Victorian Plumbing Industry Commission website has Roof and Stormwater Technical advice adopted from HB114:1998 Handbook “Guidelines for the design of eaves and box gutters” using the same design method and examples of overflows that are shown in AS/NZS 3500.5 Domestic Installations.
  • Note: All examples of acceptable overflow methods are continuous (full length) and compliant.
  • All gutter systems are required to be installed with overflow provisions.
  • “Blockages can occur anywhere along an eaves gutter causing overtopping which would not be prevented by an overflow device at the outlet of an eaves gutter.”
    All gutter overflow methods must be able to be verified that they meet the 1 in 100 year performance requirement; water must not enter the building.


  Info: This program is free and complies with the Australian Plumbing Code AS/NZS 3500.3:2015; but can be used for any Plumbing Code. Find out how to use this program for any Plumbing Code.  It does however have the ability to far exceed the range of the Code. Find out how to exceed the limits of the Charts in the Plumbing Code. 

There is no limit to downpipe size, or eaves gutter size. The code limit is 150mm for DP's and 26,800 sq mm for flat eaves gutters. 

The program will calculate the size and number of downpipes (downspouts, leaders) required, and the eaves gutter sizes for any roof.  

You can choose a downpipe size and calculate the number required, and the corresponding Eaves Gutter size. Or you can choose an Eaves Gutter size and calculate the corresponding down pipe size, and the required number.