How to replace fencing plinth with concrete slab?

[NeedDIY]

I would like to know how I can replace the plinth under the fence with concrete slabs to stop sand coming through from the other side. I have included picture of my current fence and the fence I would like it to look. 

 

[EricL]

Hello @NeedDIY 

Thanks for sharing your question about replacing your fence plinth with concrete slabs. You'll notice on the second picture that you posted that the plinth or sleepers are actually installed inside the fence post of the Colorbond fence. Technically it can be duplicated but that means that the entire fence must be taken apart in order for the sleepers to be slipped into place.

Another reason that they used timber is because it can easily be cut down to size. Concrete on the other hand is difficult to cut down. If you still wish to place the concrete sleepers in front of the opening, it will be necessary to use Steel H Posts in front of the Colorbond posts in combination with the Ridgi 1.5m x 150 x 50mm Smooth Grey Concrete Reinforced Sleeper.

One other option is to dig the sand out from the other side of the fence and place the sleepers outside and then burying them back into the sand to prevent it from being removed.

Let me call on our experienced members @Dave-1, @TedBear and @homeinmelbourne for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

[Dave-1]

Good Morning @NeedDIY 

My thinking pretty much follows @EricL 's 😕 What is on the other side of the fence is my first question and then its folowed by "How high is the sand on the other side?"  If its high then potentially you could be creating an issue down the track as the weight of the sand will push the fence out of true.

Looking at the driveway and the fence I was wondering if you put up a raised garden bed edge there, eother of bricks or the concrete sleeps you have mentioned with a "garden" behind it. That way the sand wont come through and also the weight will be distrubuted evenly through the garden bed instead of just on the posts.

Id also like to welcome you to the Bunnings community

Dave

[TedBear]

Hi @NeedDIY , looking at the pictures, I first thought that the return section (other section to that filled by sleepers) had limestone blocks under it, but is it actually filled with cement slabs on end?

I have done that with a picket fence to stop weeds coming through from a laneway.

It took a lot of digging due to the size of the slabs, so if that is what your query refers to, then I recommend buying 1/2 slabs, especially since you are only holding back sand. Using a trenching shovel, dig a little deeper than the slab needs and lean each slab into the trench, placing the end ones in each section first, so you can slide them into the channel uprights. Then place a brick under the slab to push it up into the fence's lower channel. (You will need to dig a bit wider on your side of the trench to get the brick in.) Then fill the small gaps between each slab with mortar and backfill the trench. Maybe even paint the slabs to match or contrast with  the fence first. (Limestone colour?)

[NeedDIY]

Hi @Dave-1 ,

The other side of the fence is my neighbor's property which is at higher ground level than mine hence the original plinth was put in place. The height varies along the 60m driveway with the highest at 30cm. The gap between the fence and the driveway would be too narrow to put a garden bed and I was planning to lay pebbles along the fence for minimal maintenance. My neighbor is suggesting digging from his side of the fence and putting up form board on both sides so concrete can be poured with a mesh in between to strengthen the slab. This idea would be a slow process as we will be doing up couple of fences at a time by reusing the form boards. Will this work?

[NeedDIY]

Hi @Ted 

I did think of buying pre-made slabs which I saw was on sale 30cm X 30cm and slide in between the channels but my neighbor says it would be heavy to carry the slabs. As the slabs were pre-made at that size it might not fit with my varying height.

[Dave-1]

Afternoon @NeedDIY 

The formwork would def work. Tho lots of effort would be required and the cost would be a fair bit! 60m of work ish depending on the height.

Would it be better to remove a panel at a time, fix the wooden sleeps into it and then replace the metal back into it? Same amount of work removing the sand, the weight of max 30cm high is manageble. Cost way less. I would only suggest a panel at a time to keep the structul integridy of the fence straight as you work you way along it. 

Dave

[NeedDIY]

Hi @Dave-1 

I will need 66 treated pine sleepers of 2.4m length for the 60m fence vs 4 pieces of formboard with volume of cement + sand + aggregate and a roll of 30m mesh. I think the cost is quite close but the concrete slab will be extremely time consuming.

[Dave-1]

Mmmmm @NeedDIY 

30-60m of fenceline is going to be costly all up isnt it.

I just had a cheeky thought. I do love gabion walls and have a whole bunch I have used for various things around the yard. (check my profile)

Bunnings sells a thin version that may be useful in this case. its only 150mm wide so could but up against the fence nicely (With some geotextile material to stop the sand filtering into teh baskets) Jack 650 x 300 x 150mm black rectangular gabion 

If you like the idea you can make your own longer versions with stay wires to stop the spread. I have used sandstone broken up, concrete smashed up for the fill for the cages and it looks quiet nice. (I expalin how to in a few of the projects) Gabion wall for front pathway 

The premade cages could be expensive but making up teh same size 150mm * 300mm by even 2.4m could be worth considering.

Dave

[EricL]

Hi @NeedDIY 

Based on the recommendations made, I believe it all falls down to the amount of time and effort you want to spend on this project. It's good to know that you've discussed this with your neighbour, and they are open to the idea of repairing the fence. I propose doing a list of pros and cons on a piece of paper and adding in the time factor in your list. 

Once complete, it should help you decide which plinth you'll be installing under your fence.

If you need further assistance, please let us know.

Eric