ARTIFICIAL GRASS / START BELOW THE SURFACE
Good drainage needs
somewhere to go.
Under artificial grass, you need a compatible levelling layer, a stable sub-base and an effective route for water to leave. Any membrane or underlay must work with that design. A permeable roll alone cannot fix a waterlogged garden.
Artificial grass installation brings the turf, groundwork, edges and drainage together. We plan these for homes, schools and commercial spaces across the North West, including Greater Manchester and Lancashire.
01 / THE COMPLETE ROUTE
What goes under artificial grass for drainage?
Explore the five parts of a typical garden build-up. Each has a different job; none can do the work of all the others.
Water needs to pass through the selected backing. Its product drainage rate does not describe the performance of the complete garden.
The drawing and layer descriptions are available without JavaScript. Interactive highlighting requires JavaScript.
Does artificial grass itself let water through?
Most garden turf uses a perforated or permeable backing. Check the selected product rather than assuming every backing works in the same way. Its laboratory drainage figure is not a promise that an installed lawn will clear rain at that rate.
Water can be held up by dirt in the pile, an incompatible layer, settled levels or ground that cannot accept it. A garden can therefore puddle even when the roll itself allows water through.
02 / PUT YOUR GARDEN IN CONTEXT
What should you check first?
Choose the closest answers for a focused inspection brief. No digging, measurements or contact details needed.
Your selections are used only on this page. The tool does not submit or save them.
Start with the whole route.
Tell us what you can see. We’ll highlight what to record and what to ask before choosing a base or changing the surface.
A planning aid, not a diagnosis, drainage design or assurance that the site is suitable.
Use the inspection steps below if the interactive checklist is unavailable.
03 / MATERIALS HAVE DIFFERENT JOBS
How do you choose a well-draining base?
Ask how the proposed materials work together. The familiar name on a bag is not a drainage specification.
1. Assess the ground and levels
Record standing water, soft areas, changes in height and runoff from surrounding surfaces. Set excavation depth from the planned construction and finished level. A depth copied from another garden may be wrong here.
2. Specify any separation layer
A suitable permeable geotextile can keep soil and aggregate apart. Confirm its type and position. A membrane does not create a drain, and “weed membrane” does not describe every product’s suitability.
3. Choose the structural aggregate
MOT Type 1
A dense-graded structural aggregate with fines that help it compact into a firm foundation. It is not automatically a free-draining layer or a cure for wet ground.
MOT Type 3
An open-graded material with reduced fines and greater permeability than Type 1. It may suit a design that needs water to pass through the base; it is not a universal replacement for every lawn.
Material distinction checked against Holcim’s Type 3 information. The textures show the principle, not a measured grading or product sample. Reduced fines does not mean no fines.
4. Build a stable foundation
Follow the compaction method and layer thickness specified for the selected aggregate. Loose material can settle into dips; extra compaction cannot make the wrong material into a suitable drainage system.
5. Match the levelling material
The bedding or screed layer creates a smooth finish. Sharp sand, granite fines and other aggregates differ in grading and water movement. Use a compatible material and thickness, not a generic “sand layer”.
04 / THREE PRODUCTS, THREE DIFFERENT JOBS
Do you need drainage underlay or a membrane?
They may form part of the design. None should be bought as an automatic fix for puddles.
Separation geotextile
Helps keep materials apart while allowing water movement appropriate to the specified system. Confirm the product and location within the build-up.
Ask: what is it separating?
Drainage mat or grid
Can provide a route or space for water within a designed assembly. Check load support, compatibility and where that route ends.
Ask: where does the water leave?
Shock pad
Provides cushioning within a specified system. Drainage performance also needs checking; cushioning alone does not resolve waterlogging.
Ask: what is the pad designed to do?
Concrete and paving need a different assessment
Water passing through the grass may meet an impermeable surface below. Its condition, falls, edges and effective outlet matter. An appropriate underlay can form part of that system, but cannot turn a level, enclosed slab into a drain.
Have the proposed fixing and drainage detail checked before covering the surface. Do not apply the soil-and-aggregate drawing above directly to concrete, balconies or roofs.
05 / THINK BEYOND THE BASE
What happens on clay or waterlogged ground?
More stone can provide space to hold water. That is different from creating somewhere for it to go.
Establish the cause before covering it
Persistent wetness may involve the soil, low levels, an obstructed route or extra runoff. Clay and other slow-draining ground need site assessment; a thicker aggregate layer alone may leave the same problem underneath.
Agree the destination and capacity
A designer may consider a drain or other drainage arrangement where needed. Its outlet and capacity must be suitable for the site. A trench, pipe or soakaway without a workable destination is not a complete answer.
Can you lay straight on soil if it seems dry?
For a permanent garden lawn, bare soil is not a substitute for a stable, designed base. It can soften or move later. A dry-weather visit alone does not establish year-round drainage.
06 / DESIGN AROUND THE USE
What changes for dogs or busy spaces?
Rain is not always the only liquid the installation needs to handle. Cleaning and everyday use belong in the brief too.
Dog gardens
Urine and rinse water need a suitable route through the backing and base. Repeated toilet spots, cleaning access, infill and any membrane should be considered together.
No aggregate or backing guarantees an odour-free lawn. Waste collection and cleaning remain essential. See our dog-friendly installation service and guide to choosing artificial grass for dogs.
Schools and commercial use
Heavy footfall makes stable levels and ongoing maintenance particularly important. Agree how leaves and dirt will be cleared and who checks the surface after rain.
Play equipment may need a separately specified impact-absorbing system that also manages water. Discuss the intended use with our commercial installation team; a domestic lawn detail is not a universal specification.
07 / IF THE LAWN IS ALREADY DOWN
What if artificial grass isn’t draining properly?
Start with observation and straightforward surface care. The pattern helps an installer decide what to inspect.
- 01 / CLEAR
Remove loose debris
Collect leaves and visible dirt using suitable equipment. Follow the turf’s care instructions.
- 02 / RECORD
Photograph after rain
Note where water sits, when rain stopped and whether it is clearing. Record recurring patterns.
- 03 / COMPARE
Look at the surroundings
Is water entering from paving? Are there dips, soft spots or lifting edges? Has it changed recently?
- 04 / INSPECT
Check the whole system
Persistent problems need the levels, layers and drainage route assessed before a repair is chosen.
Five shortcuts worth avoiding
01“The turf drains, so the garden will.” Check every layer and the final destination.
02“Any MOT will do.” Structural support and permeability are separate considerations.
03“A drainage mat fixes clay.” Water still needs a suitable route beyond the mat.
04“Use the same depth everywhere.” Ground, levels and intended use should set the design.
05“Replacing the roll will solve it.” First establish whether the problem is underneath.
QUICK ANSWERS
Artificial grass drainage FAQs
The details to settle before materials arrive.
What is the best base for artificial grass drainage?
A site-specific combination of stable, compatible layers and a suitable route for water to leave. The aggregate, levelling material, any membrane and the ground below need to work together.
Do you need a membrane under artificial grass for drainage?
A suitable permeable geotextile may separate soil from aggregate or serve another specified role. It does not create a drainage route by itself. Confirm the product and its position with the installer.
Is MOT Type 1 good for artificial grass drainage?
Type 1 is a dense-graded structural material, not an automatically free-draining layer. Whether it is suitable depends on the whole design. Where permeability through the base matters, a suitable open-graded aggregate may be specified.
Can artificial grass drain on clay soil?
It can when the installation is designed around the ground conditions and an effective drainage route. Adding more aggregate alone does not make waterlogged clay absorb water faster.
Does artificial grass itself let water through?
Most garden products have a perforated or permeable backing. Check the chosen turf, and remember that its drainage figure does not establish how the completed installation will perform.
Will drainage underlay stop puddles on concrete?
Not on its own. A suitable underlay may form part of the design, but the hard surface, falls, fixing detail and outlet must let water leave. Have the whole assembly assessed.
How deep should the drainage base be?
Depth follows the site assessment, selected materials, finished levels and intended use. There is no single depth that guarantees drainage in every garden, so ask for the proposed build-up in writing.
What should I ask before accepting a quote?
Ask how the ground was assessed, which base and levelling materials are specified, where water will go, and what drainage work is included. Also confirm the membrane, any underlay, edge detail and aftercare.
PLAN THE DRAINAGE BEFORE THE TURF
Let’s start with
your ground.
Send photographs, rough dimensions and details of any standing water. We can discuss the groundwork and drainage requirements as part of your installation.
Explore our artificial grass installation service. For a project in Lancashire, see our local installation coverage and include your postcode.
- Postcode, approximate size and garden access.
- Existing surface and any known base materials.
- Where puddles form and how long they remain.
- Photos of the lawn, edges and surrounding paving.
- Dogs, play equipment or other regular use.
