NCC 2016 Volume Two
Part 3.1.1 Earthworks

Part 3.1.1 Earthworks

Appropriate Performance Requirements

Appropriate Performance Requirements:

Where an alternative approach to earthworks is proposed as a Performance Solution to that described in Part 3.1.1, that proposal must comply with—

  1. Performance RequirementP2.1.1; and
  2. the relevant Performance Requirements determined in accordance with 1.0.7.



Except for Table as referenced by Figure and except for Clause for determination of a normal site as referenced by Clause 3.2.1, Part 3.1.1 does not apply in New South Wales.

Note: In New South Wales requirements for shoring and adequacy of excavation works are a prescribed condition of development consent. In addition consent authorities can place specific controls on siteworks associated with the construction of a building, by imposing further conditions of development consent. Information addressing siteworks can be found in the Department of Planning and Environment – Act and Regulation note "Health, safety and amenity during construction".

Acceptable construction practice Application

Compliance with this acceptable construction practice satisfies Performance RequirementP2.1.1 for earthworks provided:


The work is undertaken in normal site conditions.


For the purposes of this Part, normal site conditions are defined by the following parameters—


a site that is classified as A, S, M, H or E in accordance with Part 3.2; and


moisture conditions on site are as a result of seasonal and climatic changes; and


the site is not subject to unusual moisture conditions caused by drains, dams, channels, ponds or tanks which are maintained or removed from the site; and


large trees have not been recently removed from the site; and


soil moisture conditions have not been significantly modified by the removal of buildings or other structures; and


drainage on the allotment is maintained.

Explanatory information

Explanatory information:

The provisions described in Part 3.1.1 will enable earthworks to be carried out safely and avoid potential damage to adjoining structures and property through the soil collapsing or subsiding during building works. Exceptional site conditions (including the effects of torrential rain) may need special consideration and additional advice from appropriately qualified people should be considered.

State and Territory legislation may also have requirements that affect the excavation, especially in relation to adjoining property and notification to owners of that property. Advice should be obtained from the appropriate authority before commencement of works. Earthworks

Excavation and fill utilising unprotected embankments can be undertaken in accordance with—


Table for general earthwork; or

(b) for excavation adjacent to vacant adjoining property; or

(c) for excavation adjacent to existing buildings; or

(d) for fill adjacent to adjoining property. Excavation adjacent to vacant adjoining property

Excavation work, using unprotected embankments, adjacent to another allotment can be undertaken provided—


there are no buildings or structures on the adjoining allotment within 3 m of the allotment boundary adjacent to the excavation; and


the excavation commences at the allotment boundary and is within the area defined as being suitable for excavation in Figure; and


the slope of the unprotected embankment of the excavation complies with the appropriate soil classification slope described in Table Excavation adjacent to existing buildings

Excavation work for footings, drainage trenches or other similar works, adjacent to existing buildings can be undertaken provided—


the angle to determine the safe area for excavation is taken from the bottom of the shallowest point of the existing footing in accordance with Figure; and


the excavation is within the area defined as being suitable for excavation in Figure; and


the slope of the unprotected embankment of the excavation complies with the appropriate soil classification described in Table; and


for footing excavation adjacent to existing footings—


the footing is placed as soon as practicable after exposing the existing footing; and


the existing footing, where on an adjoining property, is completely isolated from the new footing by means of a flexible bond breaker not less than 10 mm thick; and


the adjoining footing is not left exposed at the completion of works.

Note: The angle for line A–A is defined in Table
Note: Line A–A is defined in Table and taken from the bottom of the shallowest point of the existing footing. Fill

Filling works may be carried out provided—


where the fill is deeper than existing soil level, the gradient of the fill complies with Table; and


where the fill is to be used to support footings or slabs, it is placed and compacted in accordance with Part 3.2.



(*see Part 3.2.4 for material description)

Compacted fill (see Part 3.2) Cut
Stable rock (A*) 2:3 8:1
Sand (A*) 1:2 1:2
Silt (P*) 1:4 1:4
Clays Firm clay 1:2 1:1
Soft clay Not suitable 2:3
Soft soils (P*) Not suitable Not suitable
1. Retaining walls or other types of soil retaining methods must be installed where—
  1. the embankment slope is steeper than that described in this Table; or
  2. the soil type is not described in this Table.
2. Embankments that are to be left exposed at the end of the construction works must be stabilised by vegetation or similar works to prevent soil erosion.