Surface Development Guideline 5

Guideline 5 applies to properties that are likely to be undermined in the future with moderate subsidence-induced ground movements.

Development that complies with this Guideline will generally accommodate the following subsidence-induced ground movements: 

Allowable residential construction

Guideline 5 allows for a single residential building that (a) is not a dual occupancy or unit development and (b) conforms with the following description:

Single storey or two storey, clad frame or articulated brick veneer residential building, erected on reinforced concrete footings/slabs, designed and constructed to comply with AS2870-2011 for a minimum Class H2 site classification. Site classification “P” for Mine Subsidence is to be ignored for these structures. 

• These buildings are limited to a maximum length of 24 metres and a maximum footprint of 400m².
• The buildings are to be designed and constructed in accordance with the current editions of AS1684, AS2870-2011, AS3600, AS3700, AS4773, the National Construction Code, and applicable Australian Standards. Masonry is to be articulated, in accordance with the current editions of Australian Standards AS3700 and AS4773.
• The gradients on wet area floors, roof gutters and drainage shall be increased to ensure that they remain serviceable when subjected to 7mm/m tilts.
• Flexible joints in pipes shall be designed and constructed to comply with AS2870-2011 for a minimum Class H2 site classification to accommodate curvature in any plane, coupled with tensile or compressive strain.
• Branches, bends and valve stems shall be protected by flexible wrapping or shrouds to prevent shearing of the pipes as ground movement occurs. Flexible joints shall be provided where pipes are connected to chambers or gullies.

Prohibited works 

The following works are not permitted under this Guideline:

• Integral retaining walls supporting the structure of the building
• Basements (including partial basements where one or more walls acts as a retaining wall)
• Suspended, drop edge or stepped slabs
• Masonry internal walls

Commercial buildings or applications for more than two separate residential buildings require assessment by Subsidence Advisory in accordance with its Merit Assessment Policy.

Other allowable additions and improvements

The below types of additions and improvements are also permitted on properties subject to Guideline 5 provided they are designed such that their connections to existing structures are articulated/flexible and any finished roof, walls and floors are not contiguous with the existing structures:

• Balconies, decks, patios, pergolas, terraces and verandas
• Driveways and hard stand spaces
• Fences
• Swimming pools (concrete or fiberglass) subject to the below:
  1. Limit of 8m length unless the parameters detailed in this section are designed for
  2. Any wet edge/infinity is adjustable and designed with sufficient freeboard to ensure that it remains operational within the parameters detailed in this section.

Exempt developments

In addition to the above, Subsidence Advisory has exempted some minor construction works from requiring approval under s22 of the Act.

For a full list of exempt developments, please refer to Subsidence Advisory’s Exempt Development list. 

Proposed developments that do not comply with Guideline 5

Applications for proposed improvements that do not comply with the Guideline assigned to the property may be assessed under Subsidence Advisory’s Merit Assessment Policy. 

Who can assess whether development complies with Guideline 5

Applications for proposed development that complies with this Guideline must be assessed by Subsidence Advisory.

Disclaimer

Please note that Subsidence Advisory’s Surface Development Guidelines are subject to change.