Pavés d'herbe robustes

How the X50 works

A gravel grid is a confinement system. The stone carries the load; the grid holds it in a closed cell so it cannot spread sideways, migrate toward the edges, or rut where wheels land in the same place every day.

That's why depth matters. A deeper cell holds a deeper layer of confined stone, and a deeper layer spreads load across a wider footprint before it reaches the sub-base. At 50mm, the X50 is built for sites where that spread has been calculated rather than assumed.

The moulded X-lattice base closes the underside of each cell, so the fill is retained rather than working its way down into the sub-base over time. Once filled, the whole installation behaves as one confined mass rather than a tray of loose stone.

Specifying the X50

Choose the X50 when:

• A drawing, engineer or consultant has specified a 50mm confined fill layer
• The site sees sustained commercial traffic: delivery vehicles, plant movements, daily service access
• You want design margin on a surface that has to stay flat for decades
• Grass has to genuinely recover between uses rather than just survive being parked on

The X40 remains the right choice for standard domestic driveways. The X30 is for sites where finished levels are constrained or you're laying over an existing hard surface. Specifying more depth than the site needs is stone you've paid to bury.

Technical data, the NBS BIM object and installation documentation are all available for specification work. Contact us for project and pallet pricing.

Choosing your stone

Fill with a 6-20mm graded blend: angular, clean, free of fines.

Most guidance in this industry recommends a single stone size. It's simple advice, and it leaves voids. Uniform particles bridge against each other, so no matter how carefully you lay them, the cell never packs solid. Those voids are space the stone settles into later, which is why single-size installations so often need topping up in the first year.

A graded blend fills them. Smaller stone wedges into the gaps between the larger, and the cell packs tight from the first pass.

This matters more than it sounds. A fully bedded cell transfers load through the stone and into the ground beneath it. A partially filled cell transfers load through the plastic cell walls instead. The stone should be doing the work, and a blend is what lets it.

Two things to avoid. Rounded shingle rolls rather than interlocking, however well graded. And anything carrying fines, dust or scalpings will bind the surface, shedding water across the top instead of through it, and giving weeds somewhere to establish. When ordering, ask your merchant for washed graded aggregate and be explicit that you don't want as-dug material.

Using the X50 for grass

The same cell, filled with rootzone instead of stone.

Depth does more for grass than most people expect. A 50mm profile holds more moisture below the surface and gives roots more room to establish before they hit anything solid. Shallow grids dry out fast in summer, and the sward fails first at the wheel tracks, which is exactly where it needs to survive.

The extra depth also sets the grid top slightly below the growing crown. Mowers pass over cleanly, and the finished surface reads as lawn rather than as plastic with grass growing through it.

Fill with a sand-dominant rootzone rather than topsoil alone, so the profile stays free-draining under compaction. Well suited to overflow car parks, event fields, emergency access routes, verge protection and any grass surface that needs to look like grass when it isn't being driven on.

Installation

Grids are pushed together by hand: no tools, no fixings, no adhesive. Orientate every grid the same way, work one row at a time, and interlock as you go. Perimeter grids cut cleanly with a hand saw or jigsaw.

On a new build-up, allow 210mm minimum excavation: 150mm of compacted sub-base, 10mm sharp sand blinding, and the 50mm grid, with stone overfilled proud of the cells.

On an existing concrete or tarmac surface, fill any holes first and use ramp edging at the entrance, bolted down with 12mm expansion bolts. Edge restraint matters on any open side: without it, the outer grids take load they weren't designed to take alone.

Overfill slightly and let traffic settle the surface, or run a whacker plate over it to bed the fill immediately. With a graded blend, the stone largely beds itself.

Full step-by-step instructions are in our gravel grid installation guide.

Drainage and permeability

The surface stays fully permeable. Water passes through the fill, through the open cell base and into the ground below, so a stabilised gravel or grass surface built on the X50 supports SuDS requirements and takes surface water out of the run-off calculation.

That only holds if the fill is clean. Fines are what turn a permeable surface into an impermeable one, which is the practical reason the stone spec matters as much as the sub-base does.

Maintenance

Very little. Correctly filled, the surface shouldn't need routine topping up: the stone hasn't gone anywhere, it's confined. Check levels after the first winter, top up any cells that have settled, and that's usually the last of it.

Individual grids can be lifted if you need access to whatever is underneath, then reinstated.

Material and end of life

Made in-house in the UK from 100% recycled polypropylene and HDPE, with full material traceability from feedstock to finished grid. Non-toxic, chemically inert, and UV stabilised for permanent external use.

IBRAN was founded in 2014 on the conviction that plastic waste is a raw material nobody was treating like one. Every X50 grid keeps post-consumer plastic locked into a product with a service life measured in decades. At end of life, grids can be returned to us for recycling.

25 year warranty, subject to documented installation.