Artificial grass

1. 1

   Excavate

   Dig out 100 to 125 mm below the finished level, allowing for the pile height of the grass.

2. 2

   Membrane and sub-base

   Lay weed membrane, then compact 75 mm of MOT Type 1 in two passes, dampening it so it binds.

3. 3

   Screed the laying course

   Spread and compact 25 mm of granite dust or sharp sand to a smooth plane, because every ripple telegraphs through the grass.

4. 4

   Fix the edges

   Install treated timber edging or a haunched concrete edge around the perimeter, leaving the drainage route open.

5. 5

   Relax the grass

   Roll the grass out and leave it two hours in the sun before cutting, with the pile running the same way on every piece.

6. 6

   Join and pin

   Join with seaming tape and outdoor adhesive, then pin the perimeter at 150 to 200 mm centres with galvanised U-pins.

7. 7

   Brush in infill

   Spread 4 to 6 kg per m2 of kiln-dried silica sand and power brush against the pile to lift it.

• Artificial grass over an impermeable base in a front garden over 5 m² may trigger the Class F planning rules. ^[1]

• Base: 75 mm MOT Type 1 + 25 mm granite dust (or sharp sand), each layer compacted. Skip the granite dust and the seams telegraph through.
• Lay on a weed membrane over the compacted base; never directly on soil.
• Use a 5 mm fall in every metre to keep the surface free-draining.
• Seaming tape needs at least 4 hours cure before brushing infill, work in dry conditions.

Artificial grass is only as good as what is under it. This is the build-up that stops dips, weeds and visible seams two summers later.

• Excavate 100 to 125 mm below the finished level, allowing for the pile height of the grass itself, usually 30 to 40 mm.
• Weed membrane on the subgrade, lapped 150 mm at joints. On heavy clay, add a geotextile separator so the sub-base does not sink into the soil.
• 75 mm of MOT Type 1 compacted in two passes with a plate compactor. Water it lightly before compacting; dry Type 1 does not bind.
• 25 mm of granite dust or sharp sand as a laying course, screeded and compacted to a smooth plane. Every ripple in this layer telegraphs through the grass.
• A second weed membrane over the laying course before the grass, then treated timber edging or a concrete haunch to fix the perimeter.
• Roll the grass out and leave it to relax for two hours in the sun before cutting. Cold rolled grass shrinks back and opens seams.
• Join with seaming tape and outdoor adhesive, pile running the same direction on every piece, then pin the perimeter at 150 to 200 mm centres with 100 mm galvanised U-pins.
• Brush in kiln-dried silica sand infill at roughly 4 to 6 kg per m2 for most pile heights, then power brush against the pile to lift it.

• Laying straight onto old lawn or bare soil. The organic layer rots, the ground settles unevenly, and the surface is hollow and lumpy within a year.
• Pile direction reversed between two pieces. The join will always show because the grass reflects light differently. Check direction before you glue, not after.
• Skipping the infill sand to save money. Infill holds the pile upright, weighs the sheet down, protects the backing from UV and helps it drain. Without it the grass flattens in a season.
• Laying over an impermeable concrete slab with no drainage. Either drill and gravel-fill drainage holes or build in a fall to a channel, otherwise the surface smells after rain.
• Sealing the edges with mortar right across the perimeter, blocking the drainage route. Use a haunched edge, not a bathtub.
• Using building sand instead of kiln-dried silica. Building sand clumps, holds water and grows moss.

• Grass itself: £12 to £35 per m2 depending on pile height, density and backing quality. Under £12 usually means a thin latex backing that splits.
• Supplied and installed with a full sub-base: typically £60 to £100 per m2 in the UK, more on small or awkward-access gardens.
• Sub-base materials for a 50 m2 lawn: roughly 8 tonnes of MOT Type 1 and 2 tonnes of granite dust.
• Spoil removal is usually the hidden cost: 50 m2 dug 100 mm deep is about 5 m3, or 7 to 8 tonnes to take away.
• Life expectancy: 10 to 15 years for a good quality grass on a proper base, 5 years or less on a poor base regardless of the grass.
• Maintenance is real but small: brush monthly, rinse in hot weather, top up infill every few years, and treat moss on shaded edges.