Retaining Wall Information Sheet (PDF 110 KB) - City of Armadale

INFORMATION SHEETRetaining WallsThis information sheet relating to retaining walls is intended as a guide only.What is a Retaining Wall?A retaining wall is a wall or structure designed and constructed to support soil at aslope steeper than can naturally be supported.Whilst retaining walls are primarily designed to support soil, they may also be placedunder a stress from other factors such as buildings, footings, vehicle loads,driveways, water and wind loads on dividing fences.Most walls are designed to support soil only, these walls are termed “nonsurcharged”It is very important to ensure the wall you intend to construct is designedto support any surcharge that may be placed upon it. Many areas within the Cityhave reactive clay soils and will require sub soil drains to be constructed with theretaining wall.A fence should not be used to retain soil unless it is designed to do so.When is a Retaining Wall Required?An embankment with a slope ratio that exceeds those described in the following tablemust be retained or appropriately stabilised.B.C.A Table 3.1.1.1Notes:For the purposes of this Table:1. Retaining walls or other types of soil retaining methods must be installed where—(a)(b)the slope ratio is more than that described in Table 3.1.1.1; orthe 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 byvegetation or similar works to prevent soil erosion.SOIL TYPEEMBANKMENT SLOPES H:L(*see Part 3.2.4 for material description) Compacted fill (see Part 3.2) CutStable rock (A*) 2:3 8:1Sand (A*) 1:2 1:2Silt (P*) 1:4 1:4Clay Firm clay 1:2 1:1Soft clay Not suitable 2:3Soft soils (P*) Not suitable Not suitable

Responsibility for ConstructionThe owner who alters the natural lie of the land is responsible to provide a retainingwall. However, where both property owners alter the levels, they would be jointlyresponsible. Each landowner has an obligation to retain soil where necessaryresulting from earthworks on his/her property. Adjoining owners who have bothundertaken earthworks are advised to attempt to negotiate a proportional baseagreement when retaining walls are required along common boundary for dividingfencing or landscaping works.The sharing of costs for the retaining is a civil matter that must be negotiatedbetween neighbours. If both parties cannot reach an agreement as to who isresponsible for retaining the difference in ground levels it may be necessary to seeklegal advice.Retaining walls are not covered in the Dividing Fence Act.Gosnells Community Legal Centre Inc. provides mediation services for resolvingneighbourhood disputes; their website address is www.gosclc.com.au.Is Council Building Licence Approval Required?A building license is required where a proposed retaining wall (greater than or equalto) ≥ 500 mm in height or located within 1m of a boundary.When the wall is situated on a common boundary, neighbours consent is required.For retaining walls (greater than or equal to) ≥1000 mm in height the City requiresthat such walls are designed by a Structural Engineer, therefore applications are tobe accompanied by signed Structural Engineer’s drawings.Positioning of Dividing Fences and Retaining WallsA dividing fence up to 1800mm high can be positioned on the higher side of aretaining wall which abuts a common boundary.Retaining walls abutting a common boundary are to be constructed entirely withinone property; they are not permitted to straddle the boundary.Building license submission requirements for retaining walls click here.For further information contact the Building Department.City of ArmadaleAdministration Office: 7 Orchard Avenue, ArmadaleMail: Locked Bag No. 2, WA Armadale 6992Tel: (08) 9399 0111 Fax: (08) 9399 0184www.armadale.wa.gov.auinfo@armadale.wa.gov.au