New tool: a paving calculator for patios and driveways

General
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Planning a patio or driveway and want a real shopping list, not just a paver count? I built a calculator that works out the whole job, pavers, bedding sand, jointing sand, sub-base and edge restraint concrete.

Most paving calculators online do one thing, divide your area by the size of one paver. That leaves out the layers that actually make paving last. I went straight to Bosun’s own paving installation guide and the Concrete Manufacturers Association’s paving specification (an extract of SANS 1200MJ) rather than guess at the numbers.

A few things it does that the quick online ones skip.

Patio and driveway are genuinely different jobs. A driveway carries vehicle weight, so it needs a compacted G5 crusher run sub-base, thicker 60mm pavers, and a herringbone pattern that resists sideways spread under load. A patio can use lighter 50mm pavers and, honestly, can get away without a proper sub-base if it is pedestrian only, though it is a cheaper option with more risk of the paving settling over time. Switching between Patio and Driveway changes the defaults so the numbers match the job.

Jointing sand is its own line, not folded into bedding sand. Bedding sand is what the pavers sit on, jointing sand is the finer sand swept into the joints afterward, they are different materials for different jobs, and both matter for the paving to lock together properly.

Edge restraints are priced in, not an afterthought. Loose pavers at the edge creep sideways and the whole area fails, not just the border. The tool works out the concrete needed to bed and haunch an edge restraint properly.

There is an honest labour estimate too, so you can see what a professional would add to the materials cost.

Try it here: Paving Calculator South Africa: Patios & Driveways

It is general information from South African paving industry guidance, not an engineering design, so a driveway on poor or clay soil, a sloped site, or anything commercial is still worth a proper contractor or engineer. I would be glad to hear if the numbers match what you have actually bought for a job.

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This is such a good idea, hey. We redid our driveway two years ago and the guy quoted us for pavers only, then halfway through the job suddenly needed more money for extra sand and edging because “it wasn’t in the original count.” At the end of the day we all just want stability, and that includes knowing what a job actually costs before you commit, not finding out in instalments.

I think a lot of people don’t realise the sub-base is the part that actually determines whether your paving lasts five years or twenty, especially with our Durban rain just sitting and softening things if the base isn’t done properly. Does your calculator factor in different soil types at all, or is it more a standard depth recommendation across the board? Also curious if it adjusts for driveways versus patios, since I’d imagine a driveway needs a heavier base to handle a car’s weight compared to just foot traffic on a patio. Would love to try it out before we finally get around to redoing our back patio.

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Sorry to hear about the driveway quote, that is exactly the kind of thing this tool was built to stop happening again. Bedding sand, jointing sand and the edge restraint concrete are all their own line items in the calculator precisely so nothing gets left off a quote and sprung on you halfway through.

On your two questions. It does differentiate driveway from patio, but not by soil type directly. Pick driveway and it locks you into 60mm pavers, a compacted G5 crusher run sub-base and a herringbone laying pattern, because that pattern is what resists the sideways spread that vehicle weight puts on the joints over time. Pick patio and the default drops to lighter 50mm pavers, plus you get an actual choice between the same G5 sub-base (still the more durable option) or compacted soil only, which is cheaper but for pedestrian traffic only, the tool shows a risk note about settling if you choose that route.

What it does not do is ask for your actual soil type and adjust the sub-base spec for it, that needs a site assessment rather than a general calculator. If Durban clay has already given you drainage or heaving trouble on that property, it is worth raising with a paving contractor before you commit rather than relying on the tool’s numbers alone. The drainage falls it assumes (1:50 across, 1:80 along the length) are the standard industry figure, not tailored to your ground conditions.

Would be good to hear how the numbers compare once you run your back patio through it.

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Nice, this is the kind of tool I’d actually bookmark. The layers thing is a big deal, most guys forget the sub-base compaction alone can eat a huge chunk of the budget on a driveway because you need way more depth than a patio for vehicle loading, usually 150mm compacted crusher run versus maybe 50 to 75mm under a patio.

One thing worth checking, does the calculator account for waste percentage on cuts? With rectangular pavers on a straight run you’re fine at maybe 5%, but the moment there’s a curve, herringbone pattern around a border, or you’re going around a pillar, wastage jumps to 10 or even 15%. I got caught out on my own braai area calculating pavers too tight and had to do a second trip to Cashbuild for one extra pack because the offcuts from the curve edge weren’t usable elsewhere.

Also curious what edge restraint method you assumed, concrete haunching versus plastic edging changes that line item a lot.

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Good questions, thanks Kabelo, and sorry about the extra trip to Cashbuild.

Yes to waste, and it comes off the same area that drives the cost, not just the count, so there’s no gap between what you’re charged for and what you actually need. Stretcher is 7%, basketweave 8%, herringbone 10% (that’s the default the moment you switch to driveway mode). There’s also a separate checkbox for “many corners, curves or a border course” that adds another 5% on top, so a herringbone driveway with a curved edge lands at 15%, which matches what you ran into on the braai area.

Edge restraint assumes concrete haunching, the same 75mm bed plus a haunch to half the paver’s height that Bosun’s installation guide specifies, mixed at 4 parts sand to 1 part cement. I haven’t added plastic edging as an option, the cost and labour are different enough that it needs its own line rather than a quick swap, but it’s a fair ask if enough people would use it over the concrete route.