The short answer
You can lay artificial grass directly over concrete, paving or a patio, which avoids digging out a base — but the key issue is drainage. The hard surface must let water escape, either through existing gaps, falls or drainage holes, or you must drill weep holes so rainwater doesn't pool under the grass. First clean and level the surface and fill any large cracks or hollows. Many installers add a foam shockpad or a thin sharp-sand/levelling underlay to smooth out the texture and add comfort, then roll out the grass, let it settle, trim it, join any seams, and fix it down with outdoor adhesive or weighted/pinned edges (you can't pin into solid concrete). A light sand infill finishes it. Sound, free-draining hard surfaces make a quick, stable base.
Laying grass on an existing patio is one of the faster installations because the hard base is already there. The work shifts from groundwork to drainage and adhesion — making sure water escapes and the grass stays put on a surface you can't pin into.
Laying on concrete at a glance
- Main concernDrainage off the hard surface
- If water can't escapeDrill weep holes
- Optional underlayFoam shockpad or sand layer
- Fixing methodAdhesive (can't pin concrete)
- FinishLight kiln-dried sand infill
Checking drainage before you start
The big difference from laying on soil is that concrete does not drain through itself, so water has to get away another way. Before doing anything, work out how the surface drains:
- Existing falls and gaps: most patios are laid to a slight fall, and paving with open joints lets water through. If yours drains well already, the grass can often sit on top and water will run off and through as before.
- Solid concrete with no fall: if water sits on the surface in puddles, it will pool under the grass too. The fix is to drill weep holes through the slab at low points (typically into a free-draining sub-base or soil below) so trapped water can escape.
- Surface condition: sweep off debris, remove moss, and fill large cracks or hollows so the finished grass lies flat without dips.
Getting drainage right at this stage prevents standing water, smells and frost problems later.
Underlay and preparing the surface
Bare concrete is hard and can telegraph its texture or any unevenness through the grass, so many installers add a layer between the slab and the turf:
- Foam shockpad / underlay: a permeable foam layer adds softness underfoot, evens out minor imperfections and is popular where children play. It must be a drainage-friendly type so water still passes through.
- Thin sharp-sand or levelling layer: on a rougher or slightly uneven surface, a thin screeded layer can create a smoother bed, though on a true patio a foam underlay is often simpler.
Whichever you choose, make sure the surface is clean, dry and level first. Any grit or unevenness left underneath will show through the finished lawn. On a smooth, sound, free-draining patio you may be able to lay the grass with no underlay at all — the choice depends on comfort, the surface condition and budget.
| Surface situation | Drainage approach | Underlay |
|---|---|---|
| Paving with open joints | Drains through joints | Optional foam |
| Patio with a fall | Water runs off | Optional foam |
| Flat solid concrete | Drill weep holes | Foam recommended |
Indicative guidance. Always assess the specific surface.
Laying and fixing the grass
With drainage and surface sorted, the grass goes down much as on any base, but the fixing method differs because you can't drive pins into concrete:
- Roll out and acclimatise: lay the grass loosely and leave it to relax flat, keeping all pieces in the same pile direction.
- Trim to fit neatly around the edges and any obstacles, cutting from the back.
- Join seams with jointing tape and adhesive where pieces meet, butting the stitch rows together and keeping fibres out of the glue.
- Fix it down: apply an outdoor-grade adhesive around the perimeter (and the seams), bonding the grass or underlay to the hard surface. On enclosed areas, weighting and edge restraints can also help, but glue is the usual method on concrete.
- Brush in a light sand infill to weigh the grass, support the blades and keep it flat.
Because there is no aggregate base to hold pins, take care that the adhesive bond is good and the edges are fully secured, so wind and foot traffic can't lift the grass.
When concrete is and isn't a good base
Laying over a hard surface is quick and avoids groundwork, but not every patio or slab is a good candidate as it stands. It is worth assessing the surface honestly before committing.
Good candidates are sound, stable surfaces that drain: paving with open joints, a patio laid to a fall, or concrete that is in reasonable condition and has somewhere for water to go. On these, the grass can go down with minimal preparation beyond cleaning, levelling and perhaps a foam underlay.
Problem surfaces need work first:
- Flat, sealed concrete with no fall holds water across its surface. Without drilled weep holes, water will sit under the grass, leading to standing water, smells and frost damage in winter. Drilling drainage points is essential here.
- Cracked or crumbling slabs can flex and let the grass move; significant cracks should be filled and loose sections made good.
- Very uneven or stepped surfaces show every imperfection through the grass, so a levelling layer or foam underlay is needed to even them out.
- Surfaces that puddle and can't drain at all — for example a slab over solid ground with no escape route for water — may not be suitable without creating drainage, and on these a conventional excavated base can be the better long-term answer.
A practical advantage of a hard base is weed suppression: a sound concrete surface gives weeds little chance to root from below, so you mainly deal with the occasional surface seed in the infill. The trade-off is that all drainage relies on the surface beneath, so getting the water away is the make-or-break factor.
If in doubt about drainage on a particular surface, watch where water collects after heavy rain and plan weep holes accordingly, or reconsider whether a soil-style excavated base would serve better. Done on a suitable, free-draining hard surface, a concrete installation is one of the fastest and most stable ways to get an artificial lawn.
Frequently asked questions
Can you put artificial grass straight onto concrete?
Yes, provided the concrete is clean, level and drains properly. If water pools on the surface you will need to drill weep holes so it can escape, otherwise water will sit under the grass. Many people add a foam underlay for comfort and to even out the surface, then glue the grass down since you cannot pin into concrete.
How do you fix artificial grass to a patio?
Because you cannot drive pins into a hard surface, artificial grass is usually bonded to a patio with an outdoor-grade adhesive around the perimeter and along any seams. The grass or underlay is glued to the clean, dry surface. Edge restraints and a sand infill add stability, but adhesive is the primary fixing on paving and concrete.
Do you need an underlay for artificial grass on concrete?
An underlay is not always essential on a smooth, sound, free-draining patio, but a permeable foam shockpad is popular because it adds softness underfoot, evens out minor imperfections and suits play areas. It must be a drainage-friendly type so water still passes through. On rough or uneven concrete an underlay also helps the grass lie flat.
Sources & further reading
Figures on this page are typical UK ranges drawn from published cost guides and are intended as guidance, not a quotation.