Concreting FAQs, Townsville

A handful of things, and none of them can be judged from your kitchen table. The first is the area in square metres, since a bigger pour uses more material and more labour. The second is the finish: plain concrete is the simplest, while exposed aggregate, coloured and polished finishes add process and cost more. The third is what is already there, because breaking out an old slab, carting the rubble away and excavating a proper base all take time before a single wheelbarrow of new concrete arrives. The fourth is access, and the last is the ground itself, which in Townsville can mean reactive clay or flood-prone low ground that needs its own base treatment. That is why every job needs a site visit. Ring us with your suburb and roughly what you want done and we will get a local concreter to come and price it properly rather than throw you a number that changes the moment they turn up.

Both are common in Townsville and both matter. Through the established central suburbs at Mundingburra, Cranbrook and Currajong the ground is reactive black-soil clay that swells in the wet and shrinks in the dry, so the base has to be deeper and better drained and the joints placed to allow for the movement. Down on the low ground near the Ross River at Idalia, Oonoonba and Railway Estate the water table sits high and the country is flood-prone, so drainage falls and sometimes subsoil drainage matter more, and the finished level has to be thought through. A concreter who works your area already knows which of these applies before they arrive.

Yes, whenever it anchors a structure. Townsville sits in cyclonic wind Region C, which means a shed slab, a patio slab, a granny flat slab and the footings all have their edge beams and tie-down designed for cyclonic wind loads, so the building they carry stays put in a blow. It is one of the biggest differences between concreting here and concreting in a calmer climate, and it is why a slab in Townsville is engineered rather than just poured flat. A concreter or engineer allows for it as part of the design.

It can, and it is one of the big things that separates bayside concreting from inland work. Homes close to the water at North Ward, Belgian Gardens, Pallarenda, the Strand and on Magnetic Island sit in salt-laden air, and that salt is what drives rust in the steel reinforcement and surface spalling, the flaking and pitting you see on older slabs near the water. The steel expands as it rusts and pushes the concrete off from the inside. The fix is not exotic. It comes down to the right mix, enough concrete cover over the reinforcement so the salt has further to travel before it reaches the steel, and sealing where it makes sense. In cyclonic Region C, where the steel is doing real structural work, that cover matters doubly. None of it is expensive to build in at pour time, but it is very expensive to retrofit once the damage has started.

For anywhere that gets wet feet and salt, exposed aggregate is the finish most people land on. Washing back the surface to reveal the stone gives grip underfoot, which matters around pools, paths and entries where people walk through in bare wet feet. It also hides marks, leaf stain and general wear far better than a smooth grey slab, and it copes well with the coastal setting at North Ward or on Magnetic Island. Plain concrete still does the job and costs less, and coloured or stencil finishes sit in between. Whichever finish you choose, the durability near the water comes from what is under the surface, the cover over the steel and the mix, not the look on top.

Sealing is not compulsory but it earns its keep in Townsville, particularly on decorative and exposed aggregate finishes and anywhere near the water. A sealer slows staining from oil, leaves and general traffic, keeps colour from fading as fast under the fierce tropical UV, and adds a barrier against the salt air that ages coastal concrete. It is not permanent. It wears off over time and needs redoing periodically, and how often depends on the product used, how much sun and traffic the area cops, and how close you are to the water. Ask your concreter what they have put down, because the product determines the reseal interval.

The slab sitting on your own land generally does not need approval, but the part where your driveway crosses the footpath and nature strip to meet the road, the vehicular crossing, does need approval from Townsville City Council, and the Council has its own specifications for how it is built. That covers the width, the profile, the materials and how it ties into the kerb. Stormwater and drainage can also come into it on low-lying blocks near the river where water has to go somewhere sensible. A concreter who works Townsville will usually know the local requirements and how to arrange the crossing, but the approval itself sits with the Council, so it is worth raising early rather than after the pour.

Walking is usually fine within a day or so, once the surface has hardened enough not to mark. Driving is a different matter. You should generally keep cars off a new driveway for about a week, and heavier vehicles such as trucks, caravans or a loaded trailer for longer again. Concrete keeps gaining strength for weeks after it looks finished, so the surface being hard underfoot does not mean it is ready to carry a car. Your concreter will give you a specific time based on the mix, the thickness and the weather. In the build-up heat pours often go in early in the morning and curing is managed closely so the slab does not lose its strength to the air.

It can, but it gets scheduled around the storms. The wet season, roughly December to March, brings intense downpours, and water landing on a fresh surface before it has set can weaken and mark the finish, so pours get postponed when the forecast is poor. The 2019 Townsville flood is a reminder of how much water can arrive here in a short time. It is frustrating to have a job pushed back a few days, but a concreter who reschedules you because of a storm is doing right by your slab. On the flip side, the hot dry build-up brings its own challenge, pouring early in the morning and managing moisture loss so the slab does not dry out too fast.

All concrete cracks to some degree. It shrinks as it cures and it moves with temperature and ground conditions, and it has very little ability to stretch. The job of a good concreter is not to stop cracking outright, which cannot be done, but to control where it happens using control joints, correct steel and a properly compacted base. Fine hairline cracks are normal and cosmetic and are nothing to lose sleep over. What is worth a look is a wide crack, a crack with a step or height difference across it, or a crack that keeps growing, because those usually point to something moving underneath, reactive clay, poor base prep, or drainage that has failed. If you are seeing that, get someone to look at it rather than filling it and hoping.

It depends entirely on what is going on top of it. A residential driveway carrying cars is typically around 100mm with reinforcing mesh through it. Anything carrying heavier loads, a truck, a caravan, a boat trailer or an industrial hardstand, needs more thickness and heavier reinforcement, and anything that anchors a structure needs its tie-down engineered for Region C. Ground conditions change it too. The reactive black-soil clay through the central suburbs can call for a different approach than a stable higher block at Douglas. Your concreter should specify the thickness and steel for your particular job rather than pouring a default, and it is a perfectly fair question to ask when they quote you.

Often, yes. If the existing slab is structurally sound, not badly cracked and has not dropped or moved, resurfacing is usually cheaper and faster than demolition and a fresh pour, and it saves you the mess of breaking the old one out. If the slab has deep cracks, a step across a crack from reactive clay, or drainage that has failed, an overlay just puts a new surface over the same problem and it will come back through within a season or two. Someone needs to stand on it and look at it to tell you honestly which situation you are in.

The whole city. That runs from North Ward and South Townsville through the central suburbs at Mundingburra, Aitkenvale and Cranbrook, out to Kirwan, Kelso and Rasmussen, north to Bushland Beach, Deeragun and Burdell, along the Ross River at Idalia and Oonoonba, and over to Magnetic Island. Our suburbs page lists everywhere we work in detail.