How to build a CURVED gabion wall

RECTILINEAR” he said. “Maybe you haven’t noticed but the basic premise of a welded mesh gabion wall is that it’s made from rectilinear components”.
“Yes, but what if they were all curved?”, I persisted. “Wouldn’t that look amazing? All those chunky textures but in lovely circles and sinuous curves…..?”
You could chine gabion mesh cages to make a really big curve but that wouldn’t work for the small radius you want…..”
At this point my husband sighed the sort of sigh that only the husband of a visionary but mad gardener could sigh. It’s the sort of sigh that says:

‘I do not understand why you feel it necessary to put me through what I know will be months of work and trial and error but I can see that there’s no point in either saying no, or complaining about it. It will be done’

Unfortunately for my husband, he’s an intelligent, resourceful and very practical man, which means he’s the perfect candidate to be tormented with such projects.
And so it began.

Landscape Concept Plan by Outhouse Design

Landscape Concept Plan by Outhouse Design

The garden design
The original garden design layout had been done by my friend Steve Warner of Outhouse Design. Unable to make decisions in my own garden, I sensibly turn to a professional to advise me, and Steve’s design featured a circular low retaining wall surrounding our established claret ash leading into a wonderful snake-like curve in front of the deck and then on to another circular paved area beyond. This distracts the eye from the existing competing straight lines of timber deck, pool and fence, none of which are parallel, making a confused jumble of shapes. As we look down on the back garden, a design that works well when viewed from above was paramount. This is something Steve is really good at – taking the constraints of a a disordered garden and creating order and pleasing shapes without regimentation or formality where none is wanted.

He’d suggested the wall, approximately 400-500mm (15-20″)** high and not retaining much could be a dry stone wall, knowing we had a lot of site stone. Then I had the whole gabion wall epiphany.

The gabion wall curves, reverse curves and also drops down along its length

The gabion wall curves, reverse curves and also drops down along its length

The wall design
The wall not only curves in a circle, and then elegantly reverse curves, but it also drops over 500mm (20″) along its length as the ground falls towards the lower circle. We couldn’t bury a lower level of gabion cages as the tree’s roots cover the whole area. The whole backyard is over sandstone floaters, so it’s not got a lot of soil in which to grow and it was really important that we didn’t damage any major anchoring or feeding roots. OK, let’s ratchet up the difficulty level another notch!

The curved gabion wall drops 7 times along its 9 metre (9 yard) length

The curved gabion wall drops 7 times along its 9 metre (9 yard) length

Small Y shaped section ties the curved gabion wall back under the deck

Small Y shaped section ties the curved gabion wall back under the deck

To keep the wall at a roughly even height, it steps down 7 times along its nearly 9 metre length, each of those step-downs only one gabion mesh square, except for the paver-topped seating area which steps down two squares to accommodate the extra thickness of the pavers. The wall is 320mm (12½”) thick to give it enough weight and solidity for a low retaining wall while maximising the size of the enclosed garden bed.

The wall also has a small curved offshoot to tie the retained section back under the deck and there’s a small 2 metre (6ft 6″) long freestanding ‘echo’ wall on the other side of the garden that blends into a low rendered wall for a colour and texture contrast.

Materials
Having looked online for what materials we could use, we went back to our (by now) friends Matt and at Ally at Permathene P/L to buy sheets of galvanised 75mm (3 inch) square gabion mesh from which to fashion our own curved gabion baskets. The mesh is made from 4mm (5/32 inch) wire – any less and it won’t hold its shape well enough.
We bought:
3 sheets of 2000mm long x 1000mm wide (= 6ft 6in x 40″)
22 sheets of 2000mm long x 500mm wide (actually 2030mm) (= 6ft 6″ x 20″)
15 brace/support rods (with hooks at each end)
25m roll x 1m wide woven weed mat (= 82ft x 40″)
300 galfan C clips
20kg bags 10mm blue metal (stabilising aggregate)
500mm (20”) wide tree root barrier
Cold galvit paint
Reinforcing rod for a ‘deadman’ and as anchor pins

Bolt cutters, tape and wire fencing tool

Bolt cutters, tape and wire fencing tool

Equipment
spade
bolt cutters
tape measure
level
stringline + metal rod as a central peg
wire twisting fencing tool
large pliers
C-clip tool (a pneumatic tool we hired from Permathene)
a car’s spare wheel

Putting in the end panels for each section

Putting in the end panels for each section

Basket design
The circle around the tree has a succession of 2030mm long (80 inch) panels forming the outside perimeter of the wall, matched by necessarily shorter length panels (approximately 1650mm = 65 inch) for the smaller radius inner curve of the back of that wall. Each of theses main sections is internally divided into thirds (every 9 squares or approximately 675mm = 26″) with a dividing panel on the radius. Because I wanted a continuous layer of rocks spread along the top, these internal dividers are cut one square lower than the 2 main end panels of each main section so a layer of rocks can cover them.

Showing cross bracing near the top of the wall that will be hidden by the top layer of stone

Showing cross bracing near the top of the wall that will be hidden by the top layer of stone

A further cross brace within each of these 600mm (24″) internal sections positioned about halfway up the wall’s height helps keep the curved side panels from bulging beyond their correct radius when filled with rocks. NOTE: this means there is a cross brace or divider about every 300mm (12″) along the length of the wall. Any further apart and the wall might bulge between supports.

Cutting the mesh panels to use as a bottom plate

Cutting the mesh panels to use as a bottom plate

There is no welded mesh with a natural radius. I have seen an installation where a bespoke base was welded and galvanised in a part circular shape to order but this is very expensive and so the bottom of the basket had to be made from sections of rectilinear mesh. We cut sections of mesh in a shape that generally followed the curved footprint of each section but they are cut a little bigger so that there’s plenty of attachment points for the long curved side panels. The easiest way to get the right size is to cut them as a ‘top’ for the two curved walls.

Sometimes the bottom mesh and slide panels aligned so that normal ‘C’ clips could be used to attach the side to the bottom, but more often the attachment had to be achieved by allowing a protruding piece of wire from the base to be wrapped around the bottom rail of the side panel.

Assembled curved gabion cages

Assembled curved gabion cages

Reo rod pin inserted into a small concrete footing

Reo rod pin inserted into a small concrete footing

To make sure the wall won’t get pushed over by expanding tree roots, there is also a reinforcing bar ‘deadman’, which ties the wall back into the garden behind it, plus two reo-bar ‘pins’ concreted into the rock below the wall to stop the base of the wall ‘sliding’ sideways.

Using a central peg and stringline to mark out both outer and inner curves

Using a central peg and stringline to mark out both outer and inner curves

Bending the wire mesh into a curve around the car's spare wheel

Bending the wire mesh into a curve around the car’s spare wheel

Creating the curves
First we marked out the radius of each curve on the plan using a central peg and stringline. If you use a constant radius for each curve, the finished curves will look much better than if you try and do it by eye. But we couldn’t find anything online that described how to bend the mesh panels to the right diameter curve so it was trial and error. The first trial was to use straps to wrap a panel around a circular water tank of about the right diameter. After leaving it for a while, the straps were released and bang! the panel snapped straight back to flat. Failure!

Treading down the curved panel to relax it back to the correct radius

Treading down the curved panel to relax it back to the correct radius

At this point Tony realised that we’d need to bend the panel beyond the curve we eventually wanted to get the mesh past its elasticity point, and then relax it back until it hit the sweet spot. But how to do all the bending while keeping the curve roughly even along the length of the panel? We needed something that was 1. round (der!) 2. strong enough not to get damaged by the metal mesh 3. not too heavy for us to manage together.

The mesh panel now stays locked in its curve

The mesh panel now stays locked in its curve

Our first thought was the heavy gas cylinder in the carport. This wasn’t bad but we found that the spare wheel from the Subaru wagon was even better as it was a larger diameter. Tony bent the mesh panels around it, by pushing it into the curve while pulling about a 600mm (24″) long section at a time. He’d then tread the curved panels down to relax them back to the right diameter and hand bend the last few squares to make the curve smoother and more consistent. When we tried to short cut without the pre-bending, we soon discovered that we couldn’t rely on the base panels to hold the whole thing in shape. It quickly wanted to ‘unbend’. So bend all the panels to the desired end shape first, then assemble.

Spreading blue metal and positioning a cutout section around an important tree root

Spreading blue metal and positioning a cutout section around an important tree root

Assembling the cages
We spread weed mat below the base mesh to prevent any weeds we hadn’t yet found and removed from growing up through the wall, as by the time you do see them, they are impossible remove. Where the ground was uneven e.g. over a large tree root we wanted to keep, we added some blue metal aggregate below the bottom mesh panel to create a level base course. In some cases we also cut the mesh panel and shaped it around the larger tree roots where they were higher than our base course. I’m sure there will be some of you who think ‘why would would you fuss about that – just cut the tree root!“‘ but, I can assure you, every major root is important to a tree’s stability and health (especially in our shallow, sandy soil), so cut them at your peril!

Painting the cut ends with cold galvit

Painting the cut ends with cold galvit

To cut the base panel pieces we positioned the curved wall panels in place, and then cut a base panel slightly wider than the wall, painting the cut ends with cold galvit.

Leaving a long cut end to loop back around the adjoining mesh

Leaving a long cut end to loop back around the adjoining mesh

Using the pneumatic C clip tool

Using the pneumatic C clip tool

To hold the separate wall mesh panels together and also to the base, we used a combination of the C-clips we’d bought, attached using the pneumatic C-clip tool we’d hired, or leaving some of the cut mesh panel ends longer and then looping them around the adjoining mesh panel using the wire twisting tool or large pliers. Although the C-clip tool was fast, it was very difficult to get it into some of the tighter spaces, especially at the base, so we found that the looping method was better in the end.

Using the wire twisting tool to loop the cut mesh ends

Using the wire twisting tool to loop the cut mesh ends

C clip attaching two mesh panels

C clip attaching two mesh panels

Tree root barrier behind the wall, conduit for lighting and deadman reo bar

Tree root barrier behind the wall, conduit for lighting and deadman reo bar

We also put a dimpled plastic root barrier behind the wall to prevent garden soil from washing into the wall. The gardens drain through to the soil below the wall so we didn’t need drainage pipes behind the wall. Finally, we added lengths of electrical conduit through the cages before we filled them so we could add low voltage wall-mounted path lights.

Showing the looped mesh method for joining two panels

Showing the looped mesh method for joining two panels

Filling the gabion cages, starting with broken concrete block

Filling the gabion cages, starting with broken concrete block

Filling the cages
Having assembled the base and the side walls, tying the base to the side, and then the main cross bracing, it is a simple but VERY laborious matter of filling the cages with cut stone for the desired effect. Each piece needs to bigger than 75mm (3″) across one face so it doesn’t slip through the mesh. Like the letterbox gabion cages, I filled the internal, unseen sections of the walls with old bricks, broken concrete blocks (from the demolished wall) and rubble, to reuse as many site materials as possible, save on removal costs and keep the good rocks for presentation. I also made small ‘bridges’ across the tree roots we wanted to save so they didn’t get squashed.

Yay! I've finished packing the first few sections!

Yay! I’ve finished packing the first few sections!

Image by GardenDrum.com

As I wanted the faces and top to look closely-tessellated, I used mostly smooth-faced sandstone rather than random or rumbled stone and kept aside pieces that had a right angle, or two, for the edge pieces and top corner stones, as well as sorting them to get a mottling of different colours. The packing took the bulk of the time spent on the whole project. Pieces had to be wedged firmly into place, often by using rubble pushed in behind them to keep them stable. We used sandstone from our own site as we have lots of exposed rock underneath the house and behind our swimming pool in quite a variety of colours. Tony cut out bits of rock and broke it into smaller pieces using a handyman-level electric demolition hammer, which cost us about $350.

The seating wall section topped with sandstone pencil-round pavers

The seating wall section topped with sandstone pencil-round pavers

Finishing off
We had initially thought the cage would need a top panel but we decided that using standard square or rectangular mesh would not look right. We then contemplated fashioning a single tie wire out of the galvanised wire of the same diameter as the welded mesh. These wires (many of them to replicate the welded mesh) could be set on the curve’s radius and both hold the two side panels parallel and add to the look by adding a radial element. But in the end we decided that it would just look too busy, and a good effect was achieved by adding some hidden radial supports just below the top row of filling stone so it was not visible. It still offered sufficient stability but didn’t detract from the look of the sandstone from above that we wanted.

We added a sitting section by mortaring on some sandstone pencil-round pavers that had been carefully angle-cut to go around the curve. To do this we finished the packed stone below the top of the cage, spread some geotextile and then concrete on top to bring it up to level. We then mortared on the pavers.

The result - functional but also very beautiful

The result – functional but also very beautiful

The result
The walls are striking, unique, and beautiful. They are not stable enough for people to walk along or sit on as they disturb the stone pieces, except where we added the paver seating slabs. But they look terrific, and the wonderful contrast between the smooth, sweeping curves and the chunky, tessellated rock is one the most admired parts of our garden.

Image by GardenDrum.com

Sinuous curves created by gabion walls – we love our garden

And yes, I have since found a new challenge for my clever and long-suffering husband – to mount a large and very heavy rusting steel ‘wheel’ sculpture delicately balanced on its narrow edge….without the support being visible!

[** I have converted metric measurements to US equivalents but US-manufactured mesh panels no doubt have slightly different overall lengths and widths.]

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    • Well you’ve got the ability and labour on hand to achieve that, although if Adam wanted to film himself doing it, I’m not sure he’d find a storage device that would take that many hours of data!

  1. This is SO beautiful I want to jump on a plane and fly to Australia NOW to see it. Shapes, colours, textures, planting: all perfect. I want one too but I need the husband to go with it!

  2. I knew you were a garden design tragic my friend but I never realised just how difficult this project was. Is this madness or genius at work? Your attention to detail to get the job just right, and Tony’s willing collusion, fill me with admiration. The world will no doubt appreciate the generous sharing of your hard-won experience and knowledge.

    • Definitely madness I fear, to embark on a hardscaping project that only you can do. I know no landscape contractor would have touched it! Although I wonder now if I might have dissuaded rather than encouraged others to have a go?

  3. I thought it was genius when I saw it, but now I know the full story I am utterly blown away! An amazing feat. Well done you both. By the way, has it got the approval of your daughter, who spurred you on in the first place?

  4. This is amazing – it looks fabulous and I wish I had somewhere to copy it!
    Love the stone and the way you packed them in Catherine. All I can say further is WOW!

  5. Such an epic and detailed project. Without the knowledge of the complexity of the project one could easily think its an “easy” project with just a few nice curves and some stones!! Surely that wouldn’t take long!! Perhaps not! This art piece is a real credit to you and Tony and your attention to detail, hard work, engineering and determination resulted in a fantastic result. I feel quite privileged to have seen the “Great Walls’ in real life, and I’m so glad I didn’t sit on it in the wrong place!
    And how’s the mounting of the steel wheel sculpture going?

    • Yes, I wonder if we’d known just how long it would take, whether we would have done it – but that’s partly my pickiness, which included redoing several cages as I wasn’t satisfied with the result, and being distracted with other projects running simultaneously. The large steel ‘Phemister’s Wheel’ as we call it (for Al Phemister, the wonderful sculptor) is mounted and looks amazing, seemingly balancing precariously right on its edge. Tony’s engineering capabilities will become the stuff of legend. At least, in his mind!

  6. You must be so pleased with the outcome, your curved gabion walls look wonderful!

    I especially like the way the shape of the gabion with grid pattern of the mesh add structure and contrast to your gardeN. You must look for excuses to go out into the garden all the time.

    You have inspired me to attempt a curved gabion seat in my own garden and I am sure the detailed information in this blog will save me countless hours of head scratching and cursing.

    THANKYOU!

    • That’s great Tracey and yes I do go out pretty much every day. Partly to look at how nice the gabon walls look but also because I feel really proud that we did it all ourselves. I’m glad I’ve both inspired and helped you. If you’ve got any questions along the way, drop by GardenDrum and ask, and I’d love to see a photo when you’ve finished (send to info@gardendrum.com)

  7. The walls (and the whole garden) look fantastic. I suggested to my husband that we could try to do something like this (in a much smaller version). He just went slightly pale and snuck away…

    Congratulations to you (and Tony)!

    • Thanks Celia. I’m very proud of what we achieved with a bit of ingenuity and hours of hard work. I think for lots of gardeners, it’s the plants that they feel most emotionally attached to, but in my garden, it’s now these walls.

    • Hi Harshal – I guess ‘expensive’ depends on what you’re comparing it to. Compared to having a stonemason come and build a dry stone wall, it’s really cheap. We had enough stone on site that we didn’t have to buy any, and we also saved money by being able to reuse part of the old block wall as fill in the centre, so we didn’t have to pay money to take it to the tip/rubbish dump. The main cost were the mesh panels (each of the 2m long by 500mm high panels cost about $20AUD) and the clips – and of course my many hours of basket filling. But if you are going to build a DIY stone wall, this is by far the cheapest way – unless you’re a stone mason!

  8. We are looking to build the same type of wall but five feet tall and two feet wide for strength . It will be for a privacy wall around a pool. Any comments or suggestions would be greatly appreciated 🙂 Cobble rock will be used and we have plenty of it . Their is some slope that tapers down . We’re looking to do approx 100 feet.

    • Hooley dooley Brandon, 1000cu ft is one heck of a lot of rock! For a wall that high you would need to build and fill it in several layers – taller gabion walls use layers of cages each around 18in high, and possibly also a heavier gauge wire as otherwise the cages will bulge once they have the weight of others on top. For a wall that long, I’m assuming that the curve’s radius is quite big so it may be easier for you to buy and adjust pre-made gabion kit cages by taking out some of the width of each on the inner side. The curve would be chined rather than smooth but it would be much faster and simpler to build.
      Alternatively, it’s only a privacy wall, why not build it as a rock-filled fence, with strong fence posts with mesh attached in two layers and then rock filled. More like the gabion fence and gate you can see in a photo in my Gabion Design Ideas post.

  9. What a great article. Very informative and helpful to me. Thank you so much for taking the time to post it.

  10. I want to do a straight retaining wall, using up absolutely tons of cement rubble which happens to be here, lying around. Actually MY Tony has built a nifty little wall about 1metre high to store it, and this wall seems stable, and looks very nicely rustic . Like a drystone dyke in Scotland.
    So I want to build it , in a cage, sunk into the ground, tethered by metal stakes, WITHOUT pouring cement to stabilise it. We would need the black plastic around it to stop tree roots from getting in.but, otherwise, I think the idea is good. I would like it to be about 1metre high.
    What do other people think?
    R.

  11. Thank you so much for sharing this. We have a very steep clay hill that we need to retain. So, we plan to use Gabion walls to create steps on the hill so that we can finally plant something, and solve the erosion issue. We didn’t think we could do it ourselves until we saw your excellent step-by-step pictures. Thank you for sharing your wisdom.

    • I always love to hear of people having a go at doing things themselves. Clay soil is tricky though as it holds so much water in the soil and expands when wet. I would cut small terraces for your gabions that slope backwards into the hill to give them extra purchase

  12. I wish I’d seen your post before I build a kind of drystone effect wall with broken slabs, on a very slight slope. It needed to curve very slightly, and I’d wanted to use gabions, but you can only buy straight ones.
    No doubt my husband is very pleased I did not see it.
    Your garden looks amazing!

  13. Thank you for this – about to embark on a very similar project and this has given me the confidence to tackle it! Looks spectacular – hopefully I can do our garden some similarity of justice!

  14. Ditto, we are also planning to build curved gabion retaining walls. I too feel a lot more confident after reading your very detailed blog.

    Thank you.