When NOT to Use Gravel Grids | IBRAN

Gravel grids are an amazingly versatile product which can be used on virtually any site to create durable, permeable surfaces. But even with that, they might not be the right fit for your project.

As a manufacturer of gravel grids, you might expect us to shout from the rooftops about how gravel grids can do anything, from surfacing your driveway to creating a runway for your private jet (please don't do this). The truth is, they're great bits of kit but they're not always the right choice for everyone.

For the average domestic driveway or car park, gravel grids are a simple and effective surfacing option which gives you durability and permeability at a lower cost per square metre installed than other surfacing options such as tarmac and concrete.

There are, however, a few cases where gravel grids aren't the right fit for you and your project.

Sometimes, with the ridiculous load capacities you see with plastic gravel grids, it's hard to forget that they are still plastic and plastic behaves in the same way plastic always does. Do you know why you see companies boasting about their load capacity when the grids are full? It's because it's not the plastic doing the weight bearing - it's the stone that does the heavy lifting. The grids are there to lock the stone together and stop it moving around. That's where the strength comes from, not the plastic. Thickening the plastic beyond a certain point will not make them any stronger.

So with this in mind, there are a few situations where gravel grids are not appropriate for the job:

1. You want to install them on a very steep slope (over 25%).

Realistically, you're never going to beat gravity with an open-cell mesh of any type. The stones will roll out of the grids, down the hill and away goes the hours of work (and £££) you've invested into the project. This kind of slope is better suited to something a little more "conventional", such as resin-bound gravel, tarmac or even concrete.

2. You drive a tank (or a tracked vehicle with huge torque)

If you're one of the lucky few to own a tank (please give me a call), gravel grids certainly aren't for you. This is one of those situations where, the grids will hold up for a while, but ultimately you will be dragging stones horizontally across the plastic mesh. Even heavy duty grids are meant for vertical loads and axle loads that are backed up by the supporting of the retained stone within. Drag granite or flint across concrete and even that would make a mark!

The same goes for if you have a driveway with limited turning space. These kinds of spaces force you to "dry wheel steer". Grinding gravel across any plastic grid like this would be like putting peanuts in a blender, except a lot less tasty.

3. You do not want any stone movement at all.

Grids hold the stone in place that is within them which in turn makes the surface layer more friction-bound as well. What they will not do, however, is stop movement of stone altogether. There will be some movement and some grids will become partially exposed in high traffic areas. It's inevitable.

If you can live with the knowledge that occasionally you will have to go over these areas and push the stones back into place, then grids will probably lock in around 98% of the stone you put into them.

But if the 2% of the stone moving around bothers you, then you will probably be better off resin-bonding the gravel together. Then you get the permeability as well at least!

4. You want something more "modern" and less "rustic".

Gravel driveways are perfect for some homeowners' style choices. They're rustic, easy to maintain and suitable for most urban or rural homes. But if you prefer something a little more "clean and modern" looking, as suits your taste, then no amount of reinforcement with grids is going to transform that natural driveway into what you want. There are a lot of stylish granites or other decorative gravels to choose from that will work with most homes but your home might simply not suit this sort of surfacing option aesthetically. Maybe a fresh, well maintained tarmac surface (with adequate drainage) or resin-bonded surfacing is a better choice for you. That's up to you!

5. You can't install a sub base or don't have the budget for it.

Whilst gravel grids can be installed over the top of an existing surface, any building project is only as good as its foundation. You can put our grids on top of existing tarmac or concrete (provided the holes are filled up properly) but our usual advice is to make sure there's an adequate sub base beneath that's level and very well compacted. If you want to take advantage of manufacturer warranties, it would be a good idea to document the installation of this as well so that you can demonstrate what's supporting your gravel grid installation.

If this sounds like too much work, or you don't have the budget, it's probably not a good idea to lay a gravel grid driveway with any grid. Not unless you plan on never driving over it.

Any company recommending you lay it straight onto bare soil (even with a membrane beneath) is setting your project up to fail. Wet soil does not hold its shape and will undermine your surface, resulting in you having to replace it after a few seasons. This is true of tarmac, concrete and resin bonded surfaces as well.

So, are gravel grids a good idea?

In most cases, gravel grids are a sustainable, permeable surfacing choice that's perfect for virtually any driveway or car parking project.