Replacing timber stumps

If your house is being reblocked, the old timber stumps are coming out — and the question is what goes in. In Victoria today the two main choices are reinforced concrete stumps and adjustable galvanised steel stumps. Timber is rarely used for replacement stumps any more, because it's exactly what's failing under most of the houses that need reblocking.

Both options are a big improvement. The right one depends on your house, your ground and your budget.

Reinforced concrete stumps

Concrete stumps are precast posts with steel reinforcement inside, set on a concrete footing poured in the ground. They're the standard choice for most restumping jobs in Geelong.

Advantages:

Durable. Concrete doesn't rot and isn't eaten by termites.
Cost-effective. Usually the lower-cost option per stump.
Good near the coast. Concrete isn't affected by salt air the way unprotected steel can be, which suits Bellarine and Surf Coast homes.
Proven. It's the most common stump type in Victorian reblocking.

Limitations:

Fixed height. Once installed, a concrete stump can't be adjusted — future re-levelling is done with packing.
Heavier to handle in very tight or low subfloors.

Adjustable steel stumps

Steel stumps are galvanised steel posts, usually with a threaded adjustable head, set on a concrete footing. They're increasingly popular, particularly where movement is expected.

Advantages:

Adjustable. The height can be fine-tuned after installation — useful if the house moves seasonally.
Lighter and easier to handle in low or awkward subfloors.
Precise levelling during installation.
Not food for termites, and don't rot.

Limitations:

Higher cost per stump in most cases.
Corrosion risk close to the sea if the galvanising is inadequate or damaged.
The footing still matters. An adjustable head doesn't make up for a poorly designed footing.

Geelong ground makes a difference

Geelong has a wide range of soils, and that affects the choice.

Reactive clay in the north and west — Bell Park, Bell Post Hill, Corio, Norlane, Hamlyn Heights and out to Lara — swells and shrinks with the seasons. Adjustable steel stumps are worth considering here because they can be re-adjusted if the house moves. Concrete on properly designed footings also performs well.
Sandy coastal soils on the Bellarine and Surf Coast drain well but can shift, and salt air is hard on steel. Concrete is usually preferred near the water.
Established suburbs like Belmont, Highton, Newtown and Geelong West have a mix, and the choice often comes down to subfloor height, access and budget.

What matters more than the stump

The stump itself is only part of a good reblock. What makes a reblock last is:

Footings designed for the soil — depth and size matter more than stump type.
Sound bearers and joists — new stumps under rotten framing don't fix anything.
Proper packing and fixings at the top of each stump.
Drainage that keeps water away from the house, especially on clay.
A building permit and inspection so the footings are checked before the house is lowered.

How long do they last?

Both concrete and galvanised steel stumps on properly designed footings should last for many decades — far longer than the timber stumps they replace. In practice, the lifespan of a reblock depends less on the stump material and more on the footing, the drainage around the house and whether the bearers above are sound. A well-built reblock on either stump type should mean you don't think about the foundations again for a very long time.

Mixing stump types

It's not unusual to see both on one job. A partial reblock might put adjustable steel stumps in a low, awkward corner of the subfloor and concrete everywhere else, or use steel along a perimeter wall on reactive clay where movement is greatest. What matters is that each stump is on a proper footing and the whole floor is packed and levelled as one system.

So which should you choose?

For most Geelong homes, reinforced concrete stumps are the sensible, cost-effective default. Adjustable steel stumps earn their extra cost on reactive clay, in low or awkward subfloors, or where you want the option of fine-tuning the floor later. Close to the coast, concrete is usually the safer choice unless the steel is heavily galvanised.

The best way to decide is to have the subfloor inspected. Once we've seen the house, the ground and the access, we'll recommend the stump that suits it — and explain why.

Concrete vs Steel Stumps: Which Is Right for Your Geelong Home?