Underpinning in Castle Hill
All five of our sample points in Castle Hill fell on the Glenorie unit, low shale hills. Most of the suburb is in The Hills Shire, whose plan maps landslide risk over parts of it; about an eighth, on the eastern side, is in Hornsby Shire, which has no landslide clause.
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Underpinning around Castle Hill
The soil-landscape report describes the Glenorie unit as low hills on Wianamatta Group shales, with narrow ridges and valleys. Its limitations include localised mass movement hazard, localised steep slopes, and localised highly plastic soil that is moderately reactive. That describes a mapped unit, not any house.
One caution about our method: our five ground-sample points missed the mapped landslide polygons, but a query over the suburb found them, so that layer covers parts of Castle Hill only. Look your lot up before assuming which council's rules apply.
Permits and The Hills and Hornsby councils rules
In The Hills, Local Environmental Plan 2019 clause 7.6 applies to land identified as Landslide risk: consent must not be granted unless the development is designed, sited, constructed and managed to avoid landslide risk, and The Hills DCP asks for a geotechnical appraisal by a qualified engineer first. In Hornsby, Local Environmental Plan 2013 clause 6.2 requires consent for earthworks unless they are exempt or ancillary to development already permitted or consented, and Council must consider drainage patterns and soil stability. Hornsby's DCP asks for a geotechnical engineer's certification on land sloping more than 20%, and asks that excavation outside the building platform stay within 1 metre of existing ground level. Neither set of documents settles whether a footing repair needs a development application.
Source: The Hills LEP 2019 cl 7.6 and DCP 2012 Part B s 2 (archive copy of 11 August 2026); Hornsby LEP 2013 cl 6.2 and DCP 2024 Part 1 s 1.3.1.4; NSW Spatial Services boundaries; read 21 September 2026. — confirm current requirements with The Hills and Hornsby councils.
Our Castle Hill service area
An enquiry from Castle Hill is referred on to an independent provider, who gets in touch to look at the house.
See all Underpinning in Sydney. We also work in Beacon Hill, where the Northern Beaches map landslip risk on sandstone.
Call (02) 9072 0403Last reviewed · Updated · First published