In most cases, yes. A granny flat or second dwelling sits on its own slab or footings, and the engineer designing them needs to know how reactive the soil is at that spot. The classification for the original house, if one exists at all, will not describe the ground under the new footprint. It is a likely question on Inala's standard three-bedroom lots, where households are larger than average. We place the boreholes near the proposed footings of the new building, test the samples in our lab and report the AS 2870 site class for the design.

Yes. A rebuild needs new footings, and those footings are designed from a current AS 2870 site classification, whether the owner lives in the house or rents it out. More than half of Inala's dwellings are rented, so this question matters to many landlords and investors here. The main practical difference is access: let your tenants know when the crew is coming and make sure our crew can reach the part of the yard where the new footings will sit.

It affects the starting point. The Housing Commission began building the estate in 1950, so many houses are around 70 years old and sit on lots laid out at that time. Houses of that age were not designed from a current AS 2870 classification, so their footings are no guide to a new design. For a rebuild or extension, the footings are designed from new soil data rather than reused, and the AS 2870 site class from our testing is what the design relies on. The history is context; the boreholes on your lot give the answer.

Yes, and it is a quick step to take early. Brisbane City Council's flood overlay in the City Plan maps river, creek and overland flow flooding, and the level of flood assessment a lot attracts depends on where it falls on that map. Parts of Brisbane's south-west are reported to have Oxley Creek tributaries running through them, so two lots close together can sit differently on the overlay. We are not able to confirm the result for your address; the council's mapping is the place to look. Do it before footing design is ordered, because the outcome shapes what the designer and certifier require.

Usually more than a single-house classification. The Queensland Government reports a 14-apartment infill social housing project in Inala, and projects of that kind generally need a wider geotechnical investigation. The scope depends on the building, the lot and the engineer's requirements, so talk to us before drilling is booked. We offer geotechnical drilling as well as site classifications and can tell you whether your project suits our scope; samples are tested in our NATA-accredited laboratory.

The test itself does not differ. The same borehole drilling, bearing tests and laboratory analysis apply either way. The AS 2870 site class follows the soil, not who lives in the house. What differs is the arrangement: a landlord or property manager usually coordinates access with tenants, and the report is often sent to an engineer or builder acting for an owner who lives elsewhere. Tell us who should receive the report when you book.

Book it before footing design starts, because the engineer needs the classification report before designing the slab and footings, and that design feeds the approval. We cannot give a fixed lead time, so ring us early in planning rather than when the plans are nearly finished. Check your lot's flood overlay at the same stage, since a flood planning area can change what the designer and certifier ask for. For older houses, it can also help to look after the site once built; QBCC publishes guidance on reactive sites.