Designing a Pool for a Sloping Brisbane Block

Half the blocks we build on in Brisbane have some kind of slope. The bay-side suburbs are reasonably flat, but get up into the western suburbs — Bardon, The Gap, Indooroopilly, Kenmore — and slopes of 1-in-4 or steeper are common.

People look at their sloping yard and assume a pool is either impossible or wildly expensive. Usually it's neither. But there are real decisions to make early, and getting them right is the difference between a clean build and a stressful one.

Three ways to handle a slope

There are essentially three approaches, and we'll talk you through which one suits your block.

1. Cut into the slope (excavate down). The pool sits below the natural ground level on the high side and emerges at deck level on the low side. This is the most common approach and usually the cleanest looking. The pool feels grounded in the landscape.

2. Raise the pool (build up). A retaining wall is built on the low side, and the pool sits in the resulting flat platform. Useful when access for deep excavation isn't possible, or when you want the pool elevated for the view.

3. Split-level / negative edge. A premium option — the pool itself drops off into a deck or lower level. Looks spectacular on the right block but adds 30-50% to the build cost.

What it adds to the budget

Sloping sites are more expensive than flat ones, no point pretending otherwise. The extra cost comes from three places:

• Engineered retaining walls (anything over 600mm needs proper design and certification)
• Reinforcement and footing depth on the deep side
• Excavation access — sometimes we have to bring in smaller machinery or work in tighter cycles

On most sloping blocks, expect to add somewhere between $8,000 and $25,000 on top of the standard package, depending on the slope and the design solution. We always break this out separately in our quotes so you can see exactly what the slope is costing.

The access question

This is the one most quoters skip past, and it's the one that bites people. Can we actually get an 8-tonne excavator into your yard? What about the concrete pump? The reo crew? The pool fencing materials?

On a steep block with a narrow side return, the answer might be 'yes but it'll cost more' — or sometimes 'no, we'll need to crane materials over the house'. Both are workable, both have a price.

This is something we work out during the site visit, not after the contract is signed. Mike will walk the block, measure access widths, check for power lines, and tell you upfront what's involved.

Engineering — the part we don't skimp on

Every Wahoo pool, sloping or not, is engineer-inspected at the steel reinforcement stage before we spray the shell. On a sloping site this matters even more, because the soil pressure on the high side and the cantilevered load on the low side both need proper design.

Our shells are 200mm thick minimum as standard — and on sloping sites we'll often push that to 250mm where the engineer recommends it. The cost difference is small. The peace of mind isn't.

If your yard slopes — start with a site visit

Almost everything about a sloping pool build is decided on the day we walk the block. Book a free site visit and we'll bring a tape, a level, and a notebook, and tell you honestly what's possible.

— Mike