House relevelling in Toowoomba

What relevelling is

Relevelling lifts a house that has sagged and holds it level without replacing the stumps. Jacks go under the bearers, the low points come up a few millimetres at a time to a laser line, and the gap between the top of the stump and the bearer is filled with galvanised steel packers, or on adjustable steel stumps the head is wound up. The trade calls it jack and pack. It suits a house whose stumps have sunk into the ground, or were packed badly last time, but are themselves sound. It does not suit a house whose stumps have rotted or been eaten, because a hollow stump cannot be packed; it has to be replaced.

The inspection decides which it is. A stump that is plumb, solid under a probe and dry at the ground line can be relevelled on. One that is soft, hollow, leaning or showing termite mud tubes is a replacement. Under most older Toowoomba houses the answer is some of each, and the quote lists which stumps are which.

Settled, not rotten: why it happens here

On the Downs side of the city a stump settles because the ground under it moves. The black vertosol under Harristown, Glenvale, Drayton and the flat suburbs west of the railway is a cracking clay, the most common soil in Queensland, and it swells when the summer storms soak it and shrinks when the dry winter takes the water back out. A concrete stump set shallow in it will sit high in March and low in September, and over twenty cycles the packing crushes, the stump tilts a little, and the floor above goes with it. The timber is fine, the stump is fine, it is just not where it was.

On the Range it is different. The red ferrosol under Newtown, East Toowoomba, Rangeville and Mount Lofty is a well-drained volcanic soil that moves far less with the seasons, so a stump that has dropped there has usually dropped for a reason: a downpipe discharging beside it for thirty years, a stump hole that was never dug to firm ground, or a corner of the house built over fill when the block was cut. The pattern is a single stump or a short run, rather than a whole side.

Near the escarpment, on the eastern slopes and the gullies, stumps on the downhill side of a cut-and-fill platform settle into the fill while the uphill ones sit on basalt. The pattern is a whole side down, which tells the story before anyone crawls under.

What the owner notices is the same whichever ground it is: a polished hardwood hallway that slopes toward one wall, doors that stick or swing open on their own, a gap opening between the skirting and the floor, a diagonal crack through the VJ boards over a door. The signs guide goes through how to read them. None of them say whether the stumps are settled or rotten; only the inspection does.

How the work runs

1. Levels. A laser or water level is run through the house and under it. The high point is found, the low points measured against it, and the pattern read: one corner down is one stump, a whole side down is drainage or fill, a dip in the middle of a room is a bearer.
2. Old packing found. Many Toowoomba houses have been relevelled two or three times since the war with whatever was on hand: bricks, hardwood offcuts, roof tiles. The crew finds it before the jacks go in, because a loose stack of brick under a bearer is not something to lift against.
3. Jacking. Hydraulic bottle jacks on hardwood pads go under the bearers near the low stumps. The house comes up in small lifts, checked against the laser each time, so VJ boards, cornices and any brick chimney are not shocked.
4. Packing. The gap is filled with galvanised steel packers bedded flat. Timber wedges are not used; they crush and the floor drops again, and they feed termites. On adjustable steel stumps the head is wound up instead.
5. Doors and cracks. As the floor comes level, doors planed to fit a sagging frame can bind and cracks can shift. Some close. The ones that do not are patched afterwards.
6. Drainage. If the stumps moved because the clay around them is alternately soaked and parched, the ground is regraded and downpipes connected to stormwater, otherwise the relevel is temporary. The soils and drainage guide covers that work.

Does relevelling need approval?

If no stump or footing is replaced and no structural component is altered, relevelling may be accepted development under Schedule 1 of the Building Regulation 2021, which covers repairs that do not affect a structural component. Council's where to start page says most structural work needs approval and some minor work does not, and Logan City Council's fact sheet puts the restumping line at 20% of the structural components. The moment a stump comes out or a bearer is cut, the question changes and a building development permit from a licensed building certifier is likely. The certifier makes that call, not the builder, and a duty certifier is at the Toowoomba Service Centre on Tuesdays and Thursdays from 9 to 4.30 if you want to ask before booking anyone.

The licence does not change with the approval. Any building work over $3,300 needs a QBCC licence in a class that covers it, which for a house is Builder Low Rise or higher, and a relevel with a crew, jacks and a day or two on site is usually over that line. Between $3,301 and $19,999 that means a Level 1 contract, written and signed before work, with the deposit capped at 10%, a cooling-off notice and the Queensland Home Warranty Scheme premium paid by the builder within 10 business days of signing. A relevel under $3,300 needs no contract and no licence, and a 20% deposit cap applies; but the same jacks, the same crew and the same risk to the house are under the floor either way, so we would still want a licensed builder.

Heritage is the other question. A relevel that puts the floor back where it was built does not change the street view, and the Heritage overlay and Neighbourhood Character overlay apply to listed places and mapped areas rather than to every old house; Toowoomba has no blanket pre-1946 rule. Where the floor would come up above the original line or the base cladding has to be altered on a listed house in East Toowoomba or Newtown, ask council's planning team first.

Timing on the Downs

A house at Harristown or Drayton relevelled in February, when the ground is at its wettest and the clay at its most swollen, can sit differently by August as the clay dries and shrinks. Where there is a choice, the levels are taken in the dry season and the relevel is done then, because the Bureau's record puts the city's wettest month in January at 132.1 mm and the driest months in winter, with July the coolest at a mean maximum of 16.3 and a mean minimum of 5.3. Spring 2019, the driest on record on the Darling Downs, is a reminder of how far the clay can shrink: the airport recorded 23.8 mm for the season against a 169.6 mm average, and houses relevelled before it were out again after it. On the red soil of the Range the season matters far less.

What a relevel quote should say

A relevel is a small job and the quote is often a line or two, which is where trouble starts. It should name the stumps that will be packed by position, the amount of lift expected at each, the packer material, and which stumps the inspection found soft, tilted or eaten and are therefore not being relevelled on. It should say whether a certifier has been asked about approval and what the answer was. It should say what happens to the bearers found soft while the jacks are under them, and how that is priced. It should carry the builder's QBCC licence number. And it should say whether the ground under the house is being regraded and the downpipes connected, because on the black clay a relevel without drainage is a relevel booked again in three summers. If the quote says relevel the house and nothing else, ask for the rest in writing before the crew arrives.