Start by watching it rain
Before anyone quotes, find out where water goes on that concrete now. Stand outside in a shower, or empty a bucket across it, and watch. A slab that sheds to a grate, a garden bed or an open edge will keep doing so under turf. A slab that ponds in one corner will keep ponding, except that afterwards you will not be able to see it happening.
That distinction is the whole guide. Turf itself is not the obstacle: Australian supply specifications generally put minimum drainage around 30 litres per square metre per hour, far more than the Coast's weather produces even in a wet month, and Norah Head AWS records its wettest month, June, at a mean 143.8 mm. Water will always get through the surface. Whether it gets away underneath is a question about the concrete.
If the fall is wrong, the fixes are the boring ones: a channel or grate cut in, a levelling screed, or accepting that a section stays paved. None of them are turf problems and all of them are cheaper to address before the adhesive comes out.
How the job runs on a slab
- 1
Check the fall
Water has to go somewhere and the slab decides where. If it currently ponds, it will pond under turf too, just invisibly.
- 2
Clean and repair
Oil, moss, loose spalling and cracks are dealt with first. Adhesive does not bond to a dirty or flaking surface.
- 3
Lay the underlay
Foam underlay of around 5mm softens the surface underfoot and evens out minor imperfections in the concrete.
- 4
Bond, do not pin
Turf adhesive holds the perimeter and the joins. There is nothing to pin into, and pinning a slab is not a solution to anything.
Underlay, adhesive and why pins are irrelevant
On soil, a perimeter is pinned at roughly 300 to 400mm intervals into a prepared edge. On concrete there is nothing to pin into, so turf adhesive does the work at the perimeter and along every join, with synthetic joining tape under the seams and the fibres kept clear of the glue.
A foam underlay of around 5mm normally goes down first. It does two things worth paying for: it takes the hardness out of the surface underfoot, which is most of the reason people put turf on concrete rather than paint it, and it evens out the minor undulations and trowel marks that would otherwise read straight through a thin turf backing. It is not a drainage layer and should not be sold as one.
Infill is usually lighter or omitted on a bonded install compared with a soil lawn, since ballast is not doing the holding-down work. Ask what your installer intends and why, because sand still helps the fibres stand up.
Humidity, backing and the coastal reality
A bonded slab install traps a thin layer between backing and concrete, and that layer stays damper than open ground. Australian trade guidance recommends polyurethane backing over latex for humid conditions, noting that latex "ages more rapidly in hot, humid environments". The Central Coast qualifies: 1215.2 mm of mean annual rainfall at Norah Head AWS over a 31-year record, and January mean minimums of 19.9C, which is the warm, humid overnight signature of this coastline.
The practical routine on a slab is slightly different from a lawn's, too. Debris cleared weekly so water can still reach the exit point, an occasional hose-through rather than a rinse, and a look under an edge once or twice a year in a shaded corner to check nothing is establishing under there. Shaded courtyards are where mould shows first, and shaded courtyards are exactly where people put turf.
The strata question, answered properly
If the slab is a balcony or a courtyard in a strata scheme, the legal position is genuinely more interesting than any competitor page will admit. There is no Australian statute, regulation, model by-law or reported tribunal decision that mentions artificial turf on a balcony. Not one. So anyone stating flatly that you can, or that you cannot, is making it up.
What actually governs it is two documents: your registered strata plan, which defines where the lot boundary sits, and your scheme's registered by-laws. Under the Strata Schemes Development Act 2015, the default horizontal boundary is the upper surface of the floor, meaning the slab and the membrane below it are common property, though a plan can and often does define it differently.
Then the Strata Schemes Management Act 2015 sorts the work into categories. Section 109 covers cosmetic work needing no approval, and it expressly includes laying carpet. Section 110 covers minor renovations needing an ordinary resolution that cannot be unreasonably withheld, and it expressly includes installing hard floors. But both carry the same exclusions: work that changes the external appearance of a lot, and work involving waterproofing. Either exclusion pushes the job into section 111, which requires a special resolution and usually a by-law.
For a typical exposed balcony that is visible from outside, the external appearance limb alone is usually enough to land you in section 111. For an enclosed courtyard nobody can see, laid loose with no adhesive and the membrane untouched, there is a plausible argument the work is cosmetic. It is untested. Ask the owners corporation in writing, and remember the tribunal's line about a strata manager's letter not constituting a special resolution.
One more point on money, because it is the part that stings. The owners corporation must maintain the original common property, including the membrane, but where an owner's own work damages common property the tribunal can order the owner to pay for repairs "including insurance and legal costs", recoverable as if they were unpaid levies. Gluing something to a membrane you do not own is a bigger decision than it looks on a Saturday.
Concrete, courtyard and balcony questions
Can turf go straight onto an existing slab?
Yes, and it is one of the more common small jobs in the villa and unit stock around Woy Woy and Ettalong Beach. There is no excavation and no crushed rock base, because the slab already is the base. What changes is the fixing method: adhesive rather than pins, usually over a foam underlay of around 5mm.
Is it cheaper than a normal lawn install?
Per square metre, usually not by as much as people expect. You save the excavation, the base materials and the spoil removal, which is real money. Against that, these jobs are almost always small, and small jobs carry a higher effective rate because mobilising, minimum material orders and setting out do not shrink with the area. Australian supplier pricing puts balcony and rooftop work at roughly $90 to $150 per square metre where membrane and drainage cells are involved.
What happens to rainwater?
It passes through the turf almost immediately, since Australian supply specifications generally put minimum drainage around 30 litres per square metre per hour, and then it does whatever the slab makes it do. If the concrete falls to a grate or an edge, it leaves. If it falls to a corner against the house, it collects there, and it will now do so out of sight. Sorting the fall is the job. The turf is the easy part.
Will it smell or grow mould underneath?
It can if water sits, which is why the fall matters more than any product choice. Australian trade material also recommends polyurethane backing over latex in humid conditions, noting latex ages more rapidly in hot, humid environments. On this coast, with a mean annual rainfall of 1215.2 mm recorded at Norah Head AWS and warm humid nights in summer, that is a sensible default rather than an upsell.
What if it is a strata balcony or courtyard?
Get the approval route right before anything is glued. Under the NSW Strata Schemes Management Act 2015, work that changes the external appearance of a lot, or that involves waterproofing, is excluded from both the cosmetic category in section 109 and the minor renovations category in section 110, which pushes it to section 111 and a special resolution of the owners corporation. That matters because on many balconies the slab and the waterproof membrane below it are common property, not yours.
Is a strata manager's approval enough?
No, and there is a NSW tribunal decision that makes the point. In a matter concerning balcony works, the Tribunal recorded that a strata manager's letter of consent "did not constitute a special resolution". If your scheme's approval route requires a resolution, a helpful email from the manager is not a substitute for it.
Does loose-laid turf avoid the whole problem?
Possibly, and honestly nobody knows for certain because no Australian case decides it. There is no statute, regulation, model by-law or reported tribunal decision anywhere in Australia that mentions artificial turf on a balcony. The argument that a loose-laid, unglued piece in an enclosed courtyard invisible from outside is cosmetic work, by analogy with laying carpet, is plausible and untested. In the same tribunal matter, the Tribunal accepted uncontested evidence that pre-existing balcony turf "was not glued or otherwise affixed to the deck", but it did not decide the point. Treat that as a reason to ask, not as permission.
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