House Raising & Build Under in Brisbane

On low-lying land across Brisbane, Ipswich and Logan, raising is often the only way to get the habitable floor above the required level while keeping the house. A flood-affected Queenslander on short stumps can be lifted clear of the defined flood level in a matter of days, far less disruption than relocating or rebuilding.

Inside Brisbane’s Traditional building character overlay, a pre-1947 house generally cannot be demolished, so a knockdown rebuild is off the table. Raising keeps the original house intact where the overlay wants it and puts all the new floor area underneath, where it barely reads from the street.

On a small inner-suburban lot the alternative is a rear extension that eats the yard and runs into setbacks and site cover. Building under adds the same area straight down with no change to the footprint, which is why the approach is so common in suburbs like Paddington, Annerley, Wilston and Camp Hill.

For the lower level to count as habitable rooms, the National Construction Code requires a minimum ceiling height of 2.4 metres in living areas and bedrooms, with 2.1 metres acceptable in some ancillary spaces such as bathrooms, laundries and corridors. Below that, you have a garage and storage, not bedrooms.

A typical Queenslander sits on stumps somewhere between 600 millimetres and 1.8 metres off the ground. Reaching a finished 2.4 metre ceiling means allowing for the new slab, the existing floor structure above it, services and linings, so the raise is usually more than the bare arithmetic suggests. On a sloping block the lift varies across the house.

Height is also constrained from above. Brisbane City Plan and the Queensland Development Code set overall building height limits that vary by zone and overlay, and in character areas the raised house still has to read as a Queenslander from the street. We confirm the maximum permissible height before we set the target level, so check current council requirements for your zone.

House raisers jack the building in stages using hydraulic jacks under the bearers, cribbing it on temporary props as it goes. Once at height it sits on props while the old stumps come out and new posts go in. In good conditions the lift itself takes days; the work around it takes months.

The new posts are typically galvanised steel or reinforced concrete, set on footings designed by a structural engineer for the site’s soil classification. Much of Brisbane is reactive clay, class H1 or H2 under AS 2870, and the footings and the new slab are designed to move with it rather than crack against it.

With the house on its new posts, the lower level is built as a conventional slab-on-ground with framed or masonry walls, and the new walls are tied to the existing floor structure with engineered connections. Bracing is redesigned for the whole building, because a house that was stable at stump height behaves differently as two storeys.

Everything that moved has to be reconnected: plumbing, drainage, electrical mains, gas, stormwater and the front stairs. It is also the moment to check the old floor for borer, rot and unapproved work while it is exposed.

A raise and build under is a substantial alteration, so the new work and anything it touches is assessed against the current NCC. Stairs need compliant risers, goings, handrails and balustrades; the old external stair rarely qualifies and is usually replaced.

The whole building gets a termite management system, not just the lower level. Wet areas downstairs need current waterproofing and ventilation. The switchboard is almost always replaced with safety switches on every circuit, and smoke alarms are brought to the interconnected photoelectric standard across both levels.

Lower-level bedrooms need adequate natural light and ventilation, which drives window sizes and runs into the boundary setbacks that constrain them. Where the lower level sits close to a boundary, fire separation may apply. All of it belongs in the drawings before anyone prices the job.

Building approval is always required and is issued by a private certifier against the NCC and the engineering. Whether you also need development approval depends on the site: in character areas, on flood-affected land or where the raised house exceeds the accepted height, the work becomes assessable development and goes through council. Check current council requirements early.

On flood-affected sites, council typically sets a minimum habitable floor level with a safety margin above the defined flood level, and this can drive the raise height more than the head height rule does. Where the margin is large, some owners accept a lower level that is garage and storage only, with the habitable rooms kept upstairs.

Most clients move out for the raise and the structural stages, then move back upstairs while the lower level is fitted out, because power, water and drainage are disconnected during the lift. We build that sequence into the program so you know the dates before you sign.

Our contract is fixed price with a clearly stated contingency for what cannot be seen before the house is up: stump condition, borer, termite damage and asbestos in old sheeting under the floor or in the bathroom. Anything found is documented and priced in writing before we act on it, and unused contingency stays with you.