When an existing concrete base may work
A sound, stable concrete area with suitable levels can provide a firm foundation for an artificial lawn. It should not be crumbling, significantly cracked, moving or covered in loose material. Large steps, raised edges and sharp protrusions can telegraph through the grass or create trip hazards. Check that doors, gates and adjoining paths will still have adequate clearance once the grass and any cushioning layer are added.
The intended use also matters. A small decorative area has different demands from a play space or a route used daily by pets. Artificial grass over a hard base can feel firmer than a lawn built over a prepared aggregate base. If comfort is important, discuss a suitable shock-absorbing layer and ensure it is compatible with the grass and the outdoor conditions.
Drainage is the main question
Concrete does not allow water to soak through like permeable soil. Before covering it, establish where rainwater currently runs and whether the surface has a fall to an appropriate outlet. If water already sits in hollows, artificial grass will not correct the underlying levels; it may hide the puddle temporarily while moisture remains trapped below. A free-draining grass backing cannot make an impermeable slab drain by itself.
Some systems rely on the concrete's falls and drainage openings at the perimeter, while others need channels or another designed route for water. The right answer depends on the location and surrounding levels. Do not block existing gullies or direct runoff towards a building or neighbouring property. The surface should be checked during rain or with a controlled water test before installation.
Preparing the concrete
Clean the surface thoroughly and remove moss, dirt, loose paint and anything that could interfere with secure fixing. Inspect for cracks and movement; stable hairline marks are different from active cracks or slabs that rock. Repair or replace defective areas before covering them. Grass laid over a deteriorating base may need to be lifted again when the concrete continues to fail.
Check the surface for sharp edges and uneven transitions. A levelling compound or suitable underlay may be appropriate in some cases, but it must be rated for exterior use and compatible with the installation. Do not use a soft indoor carpet underlay outdoors; moisture, compression and temperature changes can make it unsuitable. Follow system instructions and avoid building up the surface where it creates an awkward threshold.
Artificial grass
- Compacted, free-draining stone base
- Weed membrane beneath the grass
- Firm edging to keep the grass secure
Underlay, comfort and heat
A cushioning layer can make hard concrete more comfortable, particularly for sitting or play, but it is not always necessary. Its thickness affects door clearance, edging and the finished height. It must allow water to move to the drainage route and remain stable beneath use. Choose a product intended for outdoor artificial grass installation rather than improvising with leftover materials.
Artificial grass can become hot in direct sunshine, and a concrete base may retain heat. Consider shade, orientation and how barefoot users will experience the area. Grass is not a substitute for a safety-tested playground surface; where falls are a concern, seek appropriate advice on the complete surfacing system.
Securing the edges and joins
On soil, installers often secure the perimeter to a firm edging; concrete changes the fixing options. The grass may need a compatible adhesive or mechanical fixing method, selected for the surface and exposure. Fixings should not create sharp points or compromise drainage. The edge treatment should resist lifting from wind and regular use while leaving the drainage path open.
If more than one piece is required, joins need careful alignment and secure bonding. Pile direction should match across sections, and cuts should be made neatly so the seam is not conspicuous. Doors, steps and borders all need finished edges that cannot curl or catch a foot. Plan the layout before ordering to reduce unnecessary seams and offcuts.
When to remove the concrete instead
If the concrete is badly cracked, uneven, too high, or directs water towards the house, removal and rebuilding may be a better long-term solution. Taking it out allows a properly designed base and drainage system, although it involves excavation and waste handling. Compare the condition and level changes against the intended use rather than trying to preserve concrete simply because it is already there.
A site assessment can identify whether the concrete is sound and how water can escape. For a new installation, see our artificial grass service. The artificial grass lifespan guide explains why preparation matters, and the artificial grass cost guide covers the factors that shape the work.
Care after installation
Sweep away leaves and debris before they collect in the pile or at drainage points. Brush the fibres occasionally, especially where people walk, and rinse as appropriate if pets use the surface. Avoid hot objects such as barbecues and fire pits, which can melt synthetic fibres. Keep outlets and edges visible enough to inspect and clean.
If water begins to linger, check the outlets and surface first, then consider whether the underlying concrete has changed or was not draining properly. Maintenance cannot fix a low spot in the slab. Describing the surface, its age and how it behaves in rain helps a contractor assess the next step; use the contact page to discuss your garden.
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Frequently asked questions
Can artificial grass be laid directly on concrete?
It can be suitable in some cases, but only if the concrete is sound, suitably level and able to drain. Preparation, edge fixing and the need for cushioning should be assessed first.
Will artificial grass drain on concrete?
The grass backing may be permeable, but the concrete beneath is not. Water needs a planned route across the slab to an appropriate outlet; existing pooling should be resolved before installation.
Do I need underlay over concrete?
Not always. A suitable outdoor cushioning layer may improve comfort, but it changes the finished height and must not obstruct drainage. The intended use and condition of the base guide the choice.
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