What to Put Under Artificial Grass for Drainage

If you want artificial grass to drain properly, what goes underneath it matters just as much as the grass on top. A lot of drainage problems blamed on artificial turf are actually base problems — shallow excavation, weak sub-bases, poor compaction, or using the wrong materials underneath.

The grass itself is designed to let water pass through, but if the build-up below it cannot cope, you can still end up with puddles, soft spots, and a lawn that feels unstable underfoot. Whether you are planning a self-install or comparing quotes, understanding the right drainage base helps you avoid problems later.

🧭 Jump to:

🧱 What goes underneath for drainage?	💦 Does artificial grass itself drain water?
🏗️ Best base build-up	⚠️ Why drainage problems still happen
🐾 Best for dog-friendly lawns	🧴 What if the grass is not draining properly?
⚠️ Common mistakes	❓ FAQs

💡 Quick Answer: For most garden installations, the best drainage build-up under artificial grass includes excavated ground, a geotextile membrane, a compacted Type 1 MOT sub-base, and a thin final levelling layer such as sharp sand or fines before the grass is laid.

What Goes Under Artificial Grass for Drainage?

If drainage is the priority, you do not want to think only about the grass. You need to think about the whole build-up underneath it.

A typical well-draining domestic base includes:

• Excavated ground with enough depth removed
• Geotextile membrane to separate the soil and base layers
• Compacted Type 1 MOT as the main structural and drainage-supporting layer
• Final screed layer such as sharp sand, grano dust, or limestone fines
• Artificial grass with a permeable backing

This is the sort of build-up that gives water somewhere to go, while also helping the lawn stay solid and level over time.

Does Artificial Grass Itself Drain Water?

Yes – most domestic artificial grass has a perforated or permeable backing that allows rainwater to pass through the turf and into the base below.

That is why artificial grass can work so well in UK gardens. The surface itself is not usually the problem. The real issue tends to be whether the base underneath has been built properly enough to receive and move that water away.

So if you are asking whether artificial grass lets water through, the answer is usually yes. But whether the lawn drains well overall depends on the full system underneath it.

Why Artificial Grass Can Still Have Drainage Problems

Artificial grass itself is designed to let water pass through. The real problem usually starts below that.

Drainage issues still happen when:

• Not enough soil has been removed
• The base is too shallow
• The wrong material has been used underneath
• The sub-base has not been compacted properly
• The levels or falls are poor
• The garden was already badly drained and the build-up was not adapted for that

That is why a lawn can look fine at first but then puddle after heavy rain. In many cases, the grass gets blamed when the real issue is poor ground preparation. This is also why our guide on how to spot a bad artificial grass installation is worth reading alongside this one.

Best Base Build-Up for a Well-Draining Artificial Lawn

For most domestic gardens, this is the drainage-focused build-up we would usually recommend.

Step 1: Excavate Properly

Drainage starts with removing enough material from the existing garden. If the lawn is too shallow from the start, there is not enough room for a strong base build-up.

For many gardens, that means removing around 75mm of soil from the intended finished height. Some sites may need deeper excavation depending on the condition of the ground.

Step 2: Lay a Geotextile Membrane

The membrane sits between the soil and the base materials. It helps stop the base mixing with the ground beneath and supports a cleaner, more stable drainage layer.

People sometimes search for drainage underlay or drainage membrane for artificial grass. In many standard garden installs, that role is usually handled by a geotextile membrane as part of the wider base build rather than a magic sheet that fixes everything on its own.

Step 3: Add a Type 1 MOT Sub-Base

This is usually the most important layer for drainage and structural strength.

Type 1 MOT is popular because:

• It compacts tightly
• It creates a stable base
• It supports drainage
• It is less prone to movement over time than using too much sand alone

A drainage-friendly lawn still needs to feel firm underfoot, and this is the layer that helps make that happen. If you are comparing full base options more broadly, our what to put under artificial grass guide is worth reading alongside this one.

Step 4: Compact Thoroughly

Compaction matters just as much as material choice. A good base can still fail if it has not been compacted enough.

The sub-base should be compacted repeatedly until it is solid and stable. If this stage is rushed, dips and drainage problems are much more likely later.

Step 5: Add a Final Screed Layer

Once the Type 1 MOT is solid, a thin final screed layer is used to refine the levels and create a smooth finish before the grass goes down.

Common options include:

• Sharp sand – practical, cost-effective, and easy enough to work with
• Grano dust – very firm once compacted, but harder to screed neatly
• Limestone fines – easy to work with and very good for drainage

If you want a deeper comparison of those options, we cover that fully in what sand should you use for artificial grass?

Can You Put Artificial Grass Straight on Soil If Drainage Is Good?

Sometimes, but that does not automatically mean it is the best long-term option.

If the soil is already very well-drained, solid, and compact, there are situations where a simpler build-up may work. But for most domestic gardens, especially where mud, clay, pets, or regular use are involved, a more structured base gives a more reliable result.

In other words, “can” and “should” are not always the same thing.

If you want the full process from excavation to finished lawn, our ground preparation guide goes through it step by step.

What Is the Best Drainage Base for Dog-Friendly Artificial Grass?

For dog owners, drainage becomes even more important. A lawn that drains well is easier to keep clean, less likely to smell after heavy use, and much better at avoiding soggy patches.

That is why dog-friendly gardens usually benefit from:

• A proper compacted sub-base
• Good permeability through the backing and base
• Stable edges that do not lift or loosen
• A finish that does not stay wet for longer than it should

This is exactly why this topic supports our dog-friendly artificial grass page so well. Pet lawns are one of the clearest cases where drainage and base quality make a real day-to-day difference.

What If the Garden Is Already Boggy or Has Clay Soil?

This is where honest advice matters.

If a garden is already boggy, heavy, or slow-draining, you cannot just assume standard prep will fix everything automatically. The build-up needs to account for the ground conditions.

That usually means:

• Making sure enough depth is excavated
• Using a proper hardcore or Type 1 base
• Compacting thoroughly
• Being realistic about how the existing site behaves in wet weather

This is especially relevant in many North West gardens where ground conditions and rainfall can expose weak prep quickly. It is one reason blogs like this should also point users toward local service areas such as artificial grass in Bury and artificial grass in Greater Manchester, where drainage performance is often a real-world concern rather than a theory.

What If Artificial Grass Is Not Draining Properly?

If artificial grass is not draining properly, the issue is usually not the fibres themselves. It is more often a problem with the base, compaction, levels, or the way the garden was prepared underneath.

Common warning signs include:

• Puddles sitting on the surface after rain
• Soft spots or sinking areas underfoot
• Water collecting in the same places repeatedly
• A lawn that stays wet much longer than expected

Where the base is otherwise sound, some drainage issues can be improved. Where the whole build-up is wrong, though, the real fix is usually deeper than surface-level patching.

Common Drainage Mistakes Under Artificial Grass

The most common mistakes include:

• Not removing enough soil
• Skipping the membrane
• Using too much sand and not enough proper sub-base
• Poor compaction
• Ignoring site levels
• Assuming all artificial grass drains well regardless of the base

These are exactly the kinds of mistakes that lead to:

• Standing water
• Soft spots
• Movement underfoot
• Premature wear

If you are comparing installers, these are the issues worth asking about up front – not just the grass itself.

Does the Grass Backing Help with Drainage?

Yes, it does.

Artificial grass for domestic use usually has a perforated or holed backing that allows rainwater to pass through into the base below. That is a big part of why artificial grass works so well in UK gardens.

But again, that only works properly if the base underneath is also prepared to handle that water. The backing is part of the system, not the entire drainage solution.

FAQs About What to Put Under Artificial Grass for Drainage

If you are still weighing up the best base materials, these are the questions people usually ask next. The answers below cover membranes, sub-bases, boggy gardens, and whether the lawn can really drain well long-term.

What is the best base for artificial grass drainage?

For many domestic gardens, a geotextile membrane, compacted Type 1 MOT sub-base, and a final screed layer such as sharp sand or fines gives a strong, drainage-friendly build-up.

Do you need a membrane under artificial grass for drainage?

In most cases, yes. A geotextile membrane helps separate the soil from the base materials and supports a cleaner, more stable drainage layer.

Does artificial grass itself let water through?

Yes. Most domestic artificial grass has a permeable or perforated backing that allows rainwater to pass through into the prepared base below.

Can artificial grass drain on clay soil?

Yes, but the base preparation matters even more. Clay-heavy gardens often need proper excavation, a good hardcore or Type 1 base, and careful compaction to avoid drainage problems later.

Can you lay artificial grass on soil if the garden is not boggy?

In some cases, yes, if the soil is solid, level, and compact. But for many gardens, a more structured base gives better drainage and a longer-lasting finish.

What should go under artificial grass for dogs?

A well-draining, compacted base is especially important for dog-friendly lawns. It helps the surface stay cleaner, drier, and easier to maintain over time.

What should I do if artificial grass is not draining properly?

Usually start by checking the base, levels, and compaction rather than blaming the turf alone. Persistent puddling is often a sign the groundwork underneath needs attention.

Get Expert Advice on What to Put Under Artificial Grass for Drainage

The best drainage base under artificial grass is not just about one material — it is about the whole system working together. When the membrane, sub-base, screed, and grass are all right for the site, you get a lawn that drains well, feels stable, and lasts far longer.

At As Good As Grass, we approach drainage as part of the full installation, not an afterthought. If your garden is muddy, heavy, dog-used, or just awkward in wet weather, we can recommend the right build-up and install it properly from the ground up. Take a look at our artificial grass installation service or get in touch with our team.