News

Gravel Grids: All Your Questions Answered

7/20/2021

Whether you are new to using gravel grids or you are a topic expert, there are always questions that need answered. We have trawled through our archives, asked our distributors, installers and end users and created a concise list of questions that we get asked about gravel grids. Now we have to give fair warning, many of these questions will be specific to our own industry leading product ECCOgravel but there are also some that will be broader and could apply to gravel grids generally.

 

What are gravel grids?

Gravel grids are a base system designed to be used under gravel surfaces. Find out more in one of our recent blogs.

 

What are gravel grids used for?

They provide a stable gravel surface that aids water permeability, reduces rainwater run-off, prevents rutting / pitting / shifting and improves accessibility. They also improve the lifespan and aesthetic of your gravel surface.

 

Can you lay gravel grids on a slope?

Yes, you can! The maximum slope or gradient is 20%. This matches with a maximum inclination of about 10°. For a slope we recommend that you choose a broken gravel type, as the gravel will have more friction helping to reduce gravel shift. It is also important to lay the sheets in a half-brick bond.

 

Can you lay gravel grids on soil?

Whilst you can lay gravel grids on soil surfaces, we always recommend that for optimum performance you utilise a levelling layer (5 – 15 cm of sieved sand, limestone or porphyry). If you are intending to drive a vehicle on the surface there should be an additional foundation layer. Full information on this can be found here.

 

Can you cut gravel grids?

Yes, ECCOgravel grids can be easily cut. For simplicity we recommend using an angle grinder, a cut-off saw or a handsaw. Cutting should be simple but please take care.

 

Can you see gravel grids?

You should not be able to see gravel grids if properly installed. If they are visible, we recommend topping up the gravel to +1cm above the gravel grid. If this is a recurring problem, then you have not used enough gravel when fitting and should be topped up to +1cm across the entire surface or you have used the wrong type of gravel. We recommend speaking with your installer.

 

Are gravel grids expensive?

Ultimately the answer is no. When you consider the benefits and value that you receive from installing gravel grids. We recommend that you speak to one of our distributors or your installer to get an accurate quote including all the required components such as gravel. But a key question that can influence the price is:

Will you be driving a vehicle over the gravel surface?

When installing for a vehicular application (e.g. driveway or parking area) this requires more excavation than for a walkway or terrace. This is due to the pressure and weight, it is very important to provide a fully structured foundation, otherwise sinking might occur.

There are also two sizes of gravel grids in the ECCOgravel range, for a surface that will be driven on we would recommend you use the 4 cm thickness grid as this provides a better distribution of forces. Whilst for pedestrian traffic only, a sheet with a thickness of 3 cm will certainly suffice.

 

What size and type of gravel should I use with gravel grids?

When choosing which gravel to use with your gravel grids, there are four things you must consider:

1) The size of the gravel

We advise against choosing gravel types smaller than 4 mm in grain but would recommend no larger than 16mm, in some instances larger grain up to 20mm can be used but we strongly recommend speaking with our technical team or your landscaper before making this decision. Finer grain sizes could get stuck in shoes or wedge themselves between car tyre treads, however larger gravel will not optimally pack the honeycombs and be impact the effectiveness of the grids.

In short if the surface is going to be driven on: Gravel grain 8 – 16 mm (exceptions can apply up to 20mm depending on the aggregate seek technical support to confirm)

If the surface is mainly for pedestrian use: Gravel grain 4 – 8 mm

2) The shape of the gravel

When it comes to shape, we refer to two type of gravel:

Round Gravel (Pebbles)

Broken Gravel (standard gravel chips)

If you are wishing to drive on the gravel surface, we recommend using broken gravel, the top layer of gravel will be less likely to shift over the gravel grid’s honeycomb structure. Round gravels whilst often more aesthetically pleasing will be more likely to move over the gravel grid’s structure and are therefore better suited to pedestrian areas only.

3) The hardness of the gravel

In terms of gravel hardness it is much more effective to use a hard gravel type on any surface you intend to move over whether it be in a car or by foot. Hard gravel types are less likely to crumble under moving loads and are less likely to discolour as they will not absorb as much water. A softer rock - with a high porosity - will crumble easily and dissolve over time. This will cause puddles, rutting and discoloration. Softer gravel will also produce dust in the summer and stick to shoes and tyres in the winter.

4) The colour of the gravel

Gravel or pebbles are a natural stone and will retain their colour, even after a long time as long as you select a harder variant. When selecting which colour gravel grid to use with your gravel we suggest:

Lighter gravel - white ECCOgravel sheet

Darker or blended gravel - black ECCOgravel sheet.

 

How do you install / lay gravel grids?

We are experts at installing our own ECCOgravel grids which have a simple 7 step installation process. Find out more here

 

Do gravel grids require maintenance?

All surfaces, whether dealing with gravel sheets, grass grids, pavement stones, tiles, or wood will always require - minimal – maintenance. With ECCOgravel sheets, this maintenance is limited. Maintenance can be subdivided in 4 key areas

1) Gravel grid surface layer

Occasional inspection is advisable depending on the traffic volume and how the surface is used. It is recommended that you top up the gravel over the honeycomb sheet in places where it is exposed.

2) Leaves

Preferably clear any leaves once a year by raking, blowing, or vacuuming. Tests have shown that the minimum fraction of your gravel can never be less than 4 mm if you wish to avoid gravel pulverisation. 

3) Soil or manure

If soil or manure ends up on the surface, this is best removed with a shovel taking the gravel down to the honeycomb structure in that area. A new layer of gravel (± 1 cm) on top of the honeycomb structure is sufficient to recreate a perfect surface. The soil or manure that has washed into the hollow spaces of the honeycomb structure will have no effect on water permeability.

4) Weeds

Four top tips for preventing weeds in your gravel grids:

1)      Do not use gravel types that have a high porosity. High porosity = water is retained longer = more weeds.

2)      Do not use gravel types with high lime content, as this promotes weed growth.

3)      Create a foundation that has no nutritive constituents and that drains water well.

4)      Any remaining weeds (from seed already present in the soil initially) can be prevented from growing by the geotextile (anti-rooting mat) at the bottom of the ECCOgravel® grids. The weeds can be removed easily by hand, as the roots are concentrated in the honeycomb structure. It is also possible to remove the weeds using hot air or burners. These solutions are preferable to chemical weed killers.

 

Will gravel grids remain water permeable for the long term?

Whilst we are unable to speak on behalf of other manufacturers, we can absolutely ensure that due to the open structure of our specially designed geotextile (anti-rooting mat) that our ECCOgravel grids will remain water permeable for their lifetime. But some care is required. Do not use gravel with grains finer than 4mm

If fine particles (e.g. dust, sand, earth, remnants of leaves, …) wash onto the surface over time, this will not affect the water permeability. These fine materials will fill the voids without continuing to be compacted there. The gravel will continue to distribute the load. Due to the presence of the anti-rooting mat at the bottom of the honeycomb structure, fine fractions (e.g. dust) will not wash into the underlying foundations. This guarantees the water buffering properties of the foundations in the long term.

 

Where can you buy gravel grids?

ECCOgravel grids can be bought from our distribution partners across the globe. Find your nearest distributor here

This is far from an exhaustive list; we actively encourage you to reach out with any further questions you may have, and we will continue to build out our list.  

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