Can artificial grass be laid over decorative slate?

Can You Lay Artificial Grass Over Decorative Slate?

Decorative slate looks fantastic in a garden, but what if you decide you’d prefer a lush artificial lawn instead? Many homeowners ask whether artificial grass can be fitted over the top of existing slate. The short answer: not directly, and not easily.

Why It’s Not Straightforward

Artificial grass needs a stable, compacted base. Decorative slate is loose, uneven, and often sharp-edged. If grass is laid directly on top:

It won’t compact properly.

The surface will shift underfoot.

The sharp slate could damage the backing.

Drainage may be compromised.

This is where things become technical. Preparing slate to act as part of the sub-base isn’t a simple “cover it up” job — it takes knowledge, experience, and the right equipment.

How can it be done properly?

If you really want to re-use the slate, the process is more involved than people often realise:

1. Check drainage first

Any issues with standing water need fixed before anything else.

If the area has a natural slope, that can help surface water run off.

2. Pulverise the slate

The large decorative pieces need to be broken down into smaller chips.

Sharp edges and voids must be removed so the material can compact.

3. Blend in smaller aggregate

Mix the crushed slate with finer aggregate chips and dust.

Shovel, rake, and work it through so it creates a consistent base.

4. Compact thoroughly

Using a powerful  mechanical compactor plate, a manual tamper for example just won't do it , the whole base must be compressed into a firm, level surface.

Any soft spots or movement mean the base is not ready.

5. Top layer of fine aggregate dust

A final cushion of fine P-flow 6 mm drainage stone or whin/granite dust is spread and screeded level. P-flow would normally be used if dog urine odour is a consideration.

This gives a smooth, stable surface for the artificial grass to be laid onto.

Why Experience Matters

While the steps might sound simple written down, in practice they’re not. Getting the right mixture of materials, compaction levels, and drainage requires a trained eye. Done incorrectly, the grass will look uneven, drain poorly, or fail within a few years.

For most homeowners, it’s far easier — and ultimately cheaper — to bring in an installer who can assess whether the slate can be re-used safely, or whether it should be removed and replaced with a proper sub-base.

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✅ Key takeaway: It is possible to utilise slate as part of your sub-base, but it takes pulverising, blending, compacting, and levelling — a technical process best left to experienced artificial grass specialists (not generalists).