You can lay artificial grass straight over existing paving or concrete, and on the right surface it is one of the quickest, cleanest jobs in the trade. But it only works if the slab drains, is reasonably flat, and is not already failing — turf hides a bad surface, it does not repair one.
We do both paving and turf, so we get called to a lot of these jobs: a sun-trap concrete yard nobody uses, an old washing-line slab, a paved courtyard that feels like a car park. Turf over the top can transform them. Here is how we decide whether to do it, and the details that separate a job that lasts from one that puffs up, smells and ripples inside two summers.
The five checks before anything else
- Does water leave the surface? Stand there after rain, or run a hose on it. Water must run off to an edge, a drain or a garden bed. If it puddles, that puddle will sit under your turf forever.
- Is it structurally sound? Rocking pavers, a cracked and heaving slab, a sunken corner — all of those keep moving under the turf, and the turf will telegraph every one of them.
- How flat is it? A 10mm ridge under grass reads as an obvious line at a glance, especially in low afternoon sun. Old pavers with lipped edges are the worst offenders.
- What is the finished height going to be? Turf plus underlay adds roughly 30–60mm. That has to be checked against door thresholds, gate swings, step risers and damp-proof courses.
- Is anything organic growing there? Moss and algae under turf keep growing in the dark and damp. Kill and clean first.
Concrete: the drainage question decides it
Solid concrete is the tricky one because it is impermeable by design. There are two workable approaches:
Let it drain to the edge. If the slab has a decent fall — even 1:80 — toward a garden bed, a channel or a driveway, water simply travels along the top of the slab underneath the turf and exits. This is the cleanest solution and needs no butchery of the slab. It works well for narrow side passages and small courtyards.
Core-drill the low points. On a dead-flat slab, we drill drainage holes roughly 15–25mm in diameter at the points where water collects, typically on a grid of a metre or two, and pack the holes with stone so they do not silt up. This only works if the ground beneath the slab will actually take water — on Cape Flats sand it works well, on Durbanville clay it is far less reliable and you are usually better off draining to an edge.
Either way, artificial turf backing is perforated and will pass water. The failure is never the grass; it is the slab holding water like a tray.
Paving: usually easier, with one caveat
Permeable and sand-jointed paving is generally a better host than concrete because water already finds its way through the joints. The caveat is that turf over paving traps warmth and moisture at the joints, which encourages weed seed already sitting in the sand. Kill everything, sweep out organic debris, and treat the joints before you cover them.
The other paving-specific issue is lipping. Old bevel pavers that have started to rock produce a rippled surface under turf. If more than a few square metres are moving, the honest answer is to lift and relay that section first — localised lift-and-relay sits around R380 – R650 per m², roughly 40–60% of a full replacement, as we set out in our guide to driveway cracking causes and fixes.
Shock pad or foam underlay: what it is really for
Over a hard surface there is no soil to give underfoot, so the turf feels exactly as hard as what is under it. An underlay does three jobs:
- Comfort and safety. Essential if children will play on it, and the main reason we specify a thicker pad on rooftop and courtyard installs.
- Levelling. A closed-cell foam pad absorbs minor surface irregularities — a few millimetres, not a few centimetres.
- Drainage path. Good pads are perforated or channelled so water can travel sideways to an exit rather than sitting under the backing.
Choose a pad rated for outdoor use with drainage holes. Standard indoor carpet underlay will hold water and rot. Skipping the pad entirely is defensible on a purely decorative area nobody walks on; it is not defensible anywhere children play.
How the turf is actually held down
You cannot peg into concrete, so fixing is done at the perimeter and the seams:
- Perimeter adhesive. A continuous bead of exterior-grade turf adhesive on a band around the edge, or a bonded perimeter batten. This is what stops the south-easter getting under an edge and lifting a whole lawn like a sail — a genuine risk in Blouberg, Table View and Milnerton.
- Seams glued to joining tape. Never glued directly to the slab in the middle of the field, so the turf can move slightly with temperature.
- Weighted infill where appropriate. Silica sand infill adds ballast and helps the pile stand up. Over a shock pad, some systems use less or no infill — follow the turf manufacturer’s spec rather than habit.
Fitting is where most bad jobs are made. The seam and edge detailing is worth understanding before you accept a quote — we cover it in how to spot a bad artificial grass install.
The paving-to-turf transition
This detail is what makes a combined job look designed rather than patched. Three approaches we use:
- Flush soldier course. A single row of pavers laid on edge along the boundary, set flush with the turf pile height. Clean, crisp, and it gives the adhesive something solid to bond to.
- Steel or aluminium edging. A slim edge strip, turf tucked and glued behind it. Best for curves.
- Recessed timber or composite batten. Warmer look, works well against decking, needs to be a rot-resistant material given Cape winters.
Whatever you choose, the turf face should finish level with or a whisker proud of the paving, never below it — a lip that catches water and toes is the giveaway of a rushed job. Getting the paved portion right in the first place matters just as much; our patio and outdoor paving work is often specified alongside turf for exactly this reason.
What it costs and when it makes sense
Professionally installed artificial grass runs R350 – R650 per m² all-in depending on grass grade and site, with the grass itself between R89 and R420 per m² across budget to premium grades — the full breakdown is in our artificial grass prices guide. Laying over a sound existing surface removes excavation and base building, which is where a chunk of a normal turf budget goes, but adds the cost of underlay and adhesive. The two largely offset each other, so do not assume it is dramatically cheaper — assume it is faster and far less disruptive.
It makes most sense on courtyards, rooftop terraces, side passages, unused concrete yards and shaded areas where nothing will grow. It makes least sense as a way to avoid dealing with a slab that is cracked, heaving or holding water. If that is your situation, spend the money on the surface first.
If you are weighing turf against replanting, our comparison of artificial grass versus a real lawn runs the ten-year numbers, and our artificial lawn installation team is happy to look at an existing slab and tell you honestly whether it is a candidate.
Quick answers
Can you lay artificial grass directly on concrete?
Yes, provided the slab drains to an edge or is core-drilled at the low points, is structurally sound, and is reasonably flat. A foam or shock pad underlay is strongly recommended for comfort and to absorb minor irregularities.
Do you need drainage holes in a concrete slab under turf?
Only if the slab is flat and holds water. If it already falls toward a bed, channel or driveway, water travels along the top of the slab under the turf and exits at the edge. Drilled holes only help where the ground below actually absorbs water.
How is artificial grass fixed down on paving?
With exterior turf adhesive around the full perimeter and seams glued to joining tape, rather than pegs. A properly bonded perimeter is what stops the south-easter lifting an edge on exposed coastal properties.