Owner builders occupy a unique space in the construction world. You are managing your own build, making decisions that would normally fall to a licensed builder, and often doing significant parts of the work yourself. Concrete is one of the most critical elements of any construction and getting the supply side right is more important for owner builders than for anyone else, because you do not have a foreman’s experience to fall back on when things go sideways. This guide is written specifically for owner builders in Central Victoria who want to order concrete with confidence.

What Owner Builders Need From a Concrete Supplier

An owner builder’s needs from a concrete supplier are different from a professional contractor’s. You need someone who will explain things clearly without jargon, help you calculate the right volume without assuming you already know how, advise on mix selection for your specific application, and be available to answer questions including the ones that come up after you have already booked the delivery.

Broadmix was built for this. Our customer reviews consistently highlight the same thing: we take time to help people who are figuring things out, not just processing orders.

Common Owner Builder Concrete Projects

The most common projects owner builders contact us about in the Broadford, Kilmore, Wallan, and Seymour area include house slabs (the biggest single pour on a self-managed build), driveway and path slabs, shed bases and workshop floors, water tank pads, retaining wall footings, garage floors, pool surrounds and entertainment areas, and garden steps or edging.

Each of these has a specific mix requirement, a recommended slab thickness, and a subbase specification. We will walk you through all of it.

Choosing the Right Concrete Mix as an Owner Builder

Mix selection starts with understanding what the concrete needs to do. Strength (MPa rating) is the primary specification, but slump the workability of the mix also matters for your ability to place and finish it without specialised equipment.

Understanding Slump

Slump refers to how much a standard cone of fresh concrete sags when the cone is removed. A low-slump (stiff) mix is harder to place and work but less prone to shrinkage cracking. A high-slump mix flows easily and is self-levelling to a degree, but can be more prone to surface cracking if not handled correctly. For most owner builder applications, a slump of 80mm to 100mm strikes a practical balance workable enough to handle without specialised equipment, but not so wet that it compromises strength.

Mix Recommendations for Common Projects

For house slabs, use the specification on your building permit typically 25MPa or 32MPa as specified by your engineer. For driveways, 25MPa is standard. For pathways and garden edging, 20MPa is acceptable. For agricultural applications like farm shed floors or animal yard concrete, discuss with us some applications benefit from air entrainment or chemical resistance additives. For exposed aggregate driveways, we supply specific mixes designed for aggregate exposure see our premix concrete page at broadmix.com.au/pre-mix-concrete-plain/ for more.

Mini Mix Concrete: The Owner Builder’s Best Friend

If your project does not require a full transit mixer load typically around 5 to 7m³ — a mini mix concrete delivery is the more practical and cost-effective option. Mini mix trucks are smaller, more manoeuvrable, and can access sites that a standard truck cannot reach.

Mini mix is ideal for residential footings, small slabs, pathways, garden steps, and top-up pours. It also gives you more control: rather than committing to a full truck’s worth of concrete, you order what you actually need and avoid the stress of managing surplus.

Mini mix trucks typically carry 0.2m³ to 3m³ per load, with multiple loads possible on the same day for larger jobs that require staged pours.

Preparing Your Site as an Owner Builder

Good site preparation is the foundation literally of a good concrete result. For owner builders, this is often where the most mistakes happen, because it is less visible than the concrete itself and it is easy to underestimate its importance.

Key Steps Before Your Concrete Arrives

First, excavate to the correct depth typically 100mm for a driveway, 100mm to 150mm for a house slab depending on your engineering specification. Second, compact your subbase using a plate compactor do not rely on foot traffic or natural settlement. Third, lay crushed rock or clean gravel to an even depth and compact again. Fourth, set your formwork to the correct height and check for level. Fifth, install reinforcement mesh or steel if required by your plans, using bar chairs to keep it at the correct depth within the slab. Sixth, dampen the subbase before the truck arrives not wet, just moist.

If you are unsure about any of these steps, ask us before you book. We would rather you call with questions than have a pour go wrong on the day.

What to Have Ready on Pour Day

Even a small pour benefits from having multiple people on site. For a standard driveway or slab pour, aim for three to four people: one receiving and directing the concrete, one or two placing and spreading, and one finishing. You will need a concrete rake or screed board to level the surface, a bull float or darby for initial smoothing, and edging tools for the formwork edges. For exposed aggregate, your concreter will handle the retarder and washing but you need to be ready to assist.

Frequently Asked Questions

Can I order concrete as an owner builder without a trade account?

Yes, absolutely. Broadmix supplies concrete to owner builders, homeowners, and DIY customers without requiring a trade account. You pay for what you order, and we treat every customer regardless of whether they are a regular contractor or first-time self-builder with the same service and attention.

What permits do I need before ordering concrete for a house slab?

As an owner builder in Victoria, you need an owner builder certificate of consent from the Victorian Building Authority (VBA) for work over $16,000 in value, and a building permit from your local council before commencing structural work including footings and slabs. Your building permit will specify the concrete mix and slab design. We recommend having this documentation before you book your concrete delivery.

Can Broadmix deliver concrete for an owner builder project on a weekend?

Contact us directly to discuss weekend delivery availability. We try to accommodate owner builders who work on their builds outside of business hours, but weekend deliveries are subject to scheduling and availability. Call us as early as possible to discuss your timing needs.

How do I know how much concrete to order for my house slab?

Your building plans will include the slab dimensions and thickness specified by your engineer. Use those measurements with the formula length × width × depth = volume in m³, then add 10% for waste. If your slab has a waffle pod design, the calculation is more complex call us with your plan dimensions and we can help you work it out. Getting this right before you order is much easier than dealing with a shortfall mid-pour.

Broadmix: The Concrete Supplier Owner Builders Trust

As an owner builder, you deserve a concrete supplier who takes your project seriously regardless of its size. Broadmix is Australian owned, family run, and genuinely happy to help you navigate the concrete side of your build. From choosing the right mix to calculating your volume and scheduling delivery, we make the process as simple as possible.

Get in touch at broadmix.com.au or call us. Owner builders are some of our favourite customers and we look forward to helping you build something you’re proud of.