House Reblocking in Melbourne's West — Full & Partial Reblocks

Signs a western suburbs house is due for reblocking

Stumps tend to fail slowly, and the house drops hints for years before anything becomes unsafe. The usual giveaways are:

• A lean you can feel in the hallway, or a roll toward the middle of the house where the stumps carry the most weight.
• Internal doors that will not stay open, swing closed by themselves or scrape the floorboards.
• Cracks fanning upward from door heads and window corners, and cornices that have parted from the ceiling.
• A gap under the skirting boards that was not there when you moved in.
• Spots that feel soft or drummy in the kitchen, laundry or bathroom.
• Stumps that look tilted, cracked or eaten away in the beam of a torch held up to a vent.

Some of these have other causes, like a slow plumbing leak or a roof frame that has spread. Once you are ticking off several at the same time, the trouble is almost certainly underneath.

Why stumps fail on the basalt plains

The west of Melbourne is built on old lava flows. Over a very long time the top of that basalt broke down into a heavy grey and black clay, and that clay is among the most reactive ground in the city. A wet winter fills it with water and it swells, pushing stumps upward. A hot summer dries it out until it splits into wide cracks, and the stumps settle again. Every year the cycle repeats, and it is seldom uniform from one wall to the next, because one side may be shaded and damp while the other bakes in the afternoon sun.

The second half of the problem is age. Cottages in Footscray, Seddon and Williamstown were usually stood on red gum or other hardwood stumps, and many of those stumps are still there. Postwar homes in Sunshine, Braybrook, St Albans and Ardeer often went up on cheaper timber stumps that were never meant to last seventy years. Once the timber softens at the ground line, the clay finishes the job.

Full reblock or partial reblock?

A full reblock replaces every stump under the house. A partial reblock replaces only the ones that have gone, usually in a defined area such as a rear lean-to, a wet laundry or one side wall beside a leaking downpipe.

Partial work suits a house where most stumps are still healthy and the failed patch has an obvious cause nearby. Where the whole house still sits on its first timber stumps, patching one area often just moves the problem to the next room within a few years, so a full reblock is usually better value over time. We explain the reasoning after the inspection and leave the decision with you.

Concrete or steel?

Precast concrete stumps with steel reinforcing inside are what we fit under most western suburbs homes. They will not rot, they carry heavy loads easily and they are well proven in this clay.

Galvanised steel stumps come with a screw-threaded head, so the height can still be changed once they are in the ground. Some owners like that option on very reactive basalt clay, or where a house is likely to need minor tweaks in the years ahead. Which one we suggest hangs on the ground, how much room there is underneath and what the house above is made of, and we only make that call after a look under the floor.

How the work unfolds

A typical reblock moves through these stages:

• Inspection and scope. We take level readings, check each stump we can reach and write up what needs doing.
• Permit. The building surveyor issues approval and tells us how deep and how wide the footings must be.
• Support. Props and jacks take the weight of the house so stumps can come out safely.
• Digging. Old stumps are removed and new holes are dug, with rock broken out where the specified depth requires it.
• Hole inspection. The holes are checked before any concrete is poured.
• Stumps and lowering. New stumps go in, the house comes down onto them and the floor is packed to level.
• Repairs and tidy-up. Framing defects are fixed, then the dirt from the holes and the pulled stumps leave site with us.

Staying at home during the job

Most households live in the house the whole way through. The floor never loses its support, though you will hear the work and nobody should go under the house while it is underway. On the day the house is lowered, a few doors may need easing and water or power may be off for a short time. Plaster that is already cracked may shift slightly while the floor is brought true; leave the patching until the house has had time to settle.

Getting your figure

Every reblock is priced on the house in front of us, so we do not publish a price list. The number of stumps, how many have failed, crawl-space height, access down the side of the block, the depth to firm ground and any framing repairs all change the work involved. The inspection is free, and it gives you a written figure to weigh up.