How to build garden bed and mesh screening?

[Penny33]

Hello! I am a DIY newbie and I’ve very ambitiously started a project to build a brick raised garden bed along our 12 metre fence line. I will be putting timber frames with reo mesh screening along the fence for some climbers. See the attached 2 pictures for my inspiration.

I have dug out a 6 inch footing along the path, and am seeking some advice on the next steps.

Should I buy, assemble the frame and install the posts before I concrete? What kind of timber should I be looking for with these posts? And what type of reinforcement should I add into this channel - some kind of mesh wire?

Once the concrete is laid (with posts) I will brick the raised area. And then my next question will be what I should put against the fence line to make sure the soil doesn’t put too much pressure on the fence - maybe corrugated plastic?

Thanks in advance for any advice anyone can share!

 

 

[JacobZ]

Hi @Penny33,

A warm welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Thank you for your questions and for sharing your exciting project plans.

I'd suggest the frame is put together in situ, rather than beforehand, essentially how a fence is built. The series of articles on How To Build a Fence will have some good information that is applicable to your project.

You'll need to use H4 Treated Posts, which are treated for in ground use to ensure longevity of the timber when in direct contact with the ground. Start by concreting in your posts and bracing them nice and plumb while the concrete sets. Check out How to Set a Post for some guidance. Once the posts are in, you can build the rest of the frame.

In your trench, you should start by adding a layer of drainage gravel around 50mm thick and compact it with a tamper. This will ensure water does not pool directly beneath the footing causing erosion beneath the footing and consequently instability of the structure. 

Once compacted you can use Jack 1800 x 200mm Light Duty Reinforcing Trench Mesh to reinforce your footing. Make sure the reinforcing is fully encased within the concrete on all sides. If it pokes out of the concrete or is sitting on the ground, this becomes an entry point for moisture which can over time cause the reinforcing to rust.

Due to the limited depth in your garden bed, our options for supporting the soil from behind are quite limited. Your suggestion of corrugated plastic seems like a good idea, but you'll have to support it on the fence side in some way. You could use some star pickets along the fence line and attach the corrugated plastic to them so they load on them is transferred down into the ground. Alternatively, you could screw the corrugated plastic on to the back of the posts, but due to the limited space, I'm not sure how you could best achieve this. If you could remove the fence panels temporarily, this might be an option.

Allow me to tag @Dave-1, @Nailbag and @Jewelleryrescue to see what they think of the project and if they have any advice to offer.

Let me know if you have any further questions.

Jacob

[Nailbag]

Hi @Penny33 

@JacobZ has pretty much covered everything very well. Unless I am missing something in the design, my only main concern I have is that the fence can't/shouldn't be utilised to support the back side of the garden bed. The raised garden needs to be completely independent of the fence as it's not built to act as a retaining wall for all that soil and pressure of a growing garden, especially as it appears it's already quite old.

My suggestion would be to build a retaining wall in front of the fence using 2 - 3 rows of 200mm x 50mm treated pine sleepers, which are quite economical to buy. You would then line the inside with builders plastic to seperate the soiled from the sleepers.

Sorry to complicate your build.

Nailbag

 

[Dave-1]

Godo Morning @Penny33 

Nice idea with the mesh and posts, I am not keen for having the fence support the back of the garden bed tho.

@JacobZ  and @Nailbag's ideas are the same as mine in this regard. Corrorgated plastic wont have the structual strenth to keep the soil away from the fence and fenceposts and would end up pushing the fence over slowly.

With your trench for the foundation of the brickwork I would suggest to go at least twice as deep, then have the reo mesh that @JacobZ has mentioned. The thinner the base to distruibute the load the higher the chance of the concrete cracking and it being transfered through to your brick work.

The last part I would suggest is 600mm deep holes for the posts that you want. The higher you go the deeper the posts need to be, Think of the minimal pressure applied at the top of a post to wiggle it so if the wind picks up or plants pull as they grow then your hard work will start to look not so good.

Dave