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.
💧 Quick Answer: What should you put under artificial grass for drainage?
- A geotextile membrane to separate the base from the soil
- A compacted Type 1 MOT sub-base for structure and drainage support
- A thin final screed layer such as sharp sand, grano dust, or limestone fines
- Proper compaction and levelling throughout
- Extra attention to site conditions if the garden is already boggy or heavy with clay
Need Help Fixing a Boggy Garden or Poor Drainage?
We install artificial grass with the right groundwork, drainage base, and finish for your garden. If you want honest advice on what should go underneath your lawn, our team can help.
🔑 Quick Takeaways
- The grass backing drains through, but the base underneath must still be built properly.
- Type 1 MOT is usually the key drainage-friendly structural layer for domestic garden installs.
- A membrane and final screed layer both matter if you want a lawn that looks smooth and drains well.
- Bad drainage is usually a groundwork issue, not an artificial grass issue.
🧭 Jump to:
| 🧱 What goes underneath for drainage? | 💦 Why drainage problems still happen |
| 🏗️ Best base build-up | 🐾 Best for dog-friendly lawns |
| ⚠️ 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.
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.
This is one of those simple steps that makes more difference than people realise.
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.
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?
| Layer | What It Does | Why It Helps Drainage |
|---|---|---|
| Geotextile membrane | Separates soil from the base | Helps keep the drainage layer cleaner and more stable |
| Type 1 MOT | Forms the main sub-base | Supports water movement while keeping the lawn structurally solid |
| Final screed layer | Refines levels before fitting | Helps create a neat finish without trapping surface water |
| Permeable grass backing | Lets rainwater pass through | Allows water to drain into the prepared base below |
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, where drainage performance is often a real-world concern rather than a theory.
🛠️ Expert Insight: The best drainage base is not just about one miracle material. It is about the full build-up being right – excavation, membrane, sub-base, compaction, and screed. That is usually what separates a lawn that drains brilliantly from one that puddles after every spell of rain.
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.
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.
Does artificial grass itself drain water?
Yes. Most domestic artificial grass has a permeable backing that lets rainwater pass through into the prepared base below.
Want a Lawn That Drains Properly All Year Round?
We install artificial grass with the right drainage build-up for domestic gardens, pet lawns, and more demanding sites. If you want a proper quote based on your garden, not guesswork, speak to our team today.
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.
