Underpinning in Bald Hills
A large part of Bald Hills is mapped in Brisbane City Council's creek and waterway flood planning area, and Queensland's geological survey puts our five sample points on four different units, two of them coastal deposits. CSIRO says saturation can leave clay ground with virtually none of its bearing capacity, so water is a sensible first question here.
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Underpinning around Bald Hills
Two of the five sample points are old alluvial plain, Pleistocene sand, silt, clay and gravel. One is a Holocene coastal-plain deposit that the survey describes as including peat, and another is coastal tidal flat, mangrove flat and saltpan. The fifth is the Petrie Formation, a Paleocene to Eocene unit of mudstone, siltstone, sandstone, oil shale, brown coal and limestone. No unit covers more than two of the five points.
CSIRO lists leaks, blocked gutters, downpipes that end at the wall and over-watered garden beds as the ordinary sources of saturation near a footing, and QBCC's inspectors check for leaking taps, air conditioning lines discharging next to footings, and blocked gutters and downpipes. Where this much of a suburb is in a flood planning area, those are the checks to make before anyone digs.
Permits and Brisbane City Council rules
Filling or excavating more than one vertical metre for a building or structure needs building approval, Council says, and Council also warns that overlays affect the amount that needs no planning approval. With a flood planning area over much of Bald Hills, check the mapping for your lot on City Plan online first, then put the dig to a licensed building certifier.
Source: Brisbane City Council, Filling and excavation page (read 21 September 2026); City Plan 2014 creek and waterway flood planning area mapping, last modified 23 September 2025. — confirm current requirements with Brisbane City Council.
Our Bald Hills service area
An enquiry from Bald Hills is referred on to an independent provider, who gets in touch to look at the house.
See all Underpinning in Brisbane. We also work in Bridgeman Downs, where the same flood mapping covers a smaller share.
Call (07) 3523 1792Last reviewed · Updated · First published