Gabion Retaining Wall - Planning Permission Required?

[s1977]

Hi All

Seeking some guidance here. Our garden is split across 2 levels, one at house level and one about a metre below. That section is approximately 3-4m by 20m. I am considering using gabions as a gravity retaining wall. We have dug a foundation 0.5m deep and 1m wide along the entire length of the garden and was planning to build a 2 step gabion wall with base layer 1m deep with the top layer 0.5m, so 1.5m overall in height from foundation base to top. That will bring the rear garden flush with the rest of the garden and I can then extend the lawn to cover the entire garden.

I was reading about planning permission when I came across the below clause regarding needing planning permission where the wall is in proximity to vehicles. It states "it is next to a highway used by vehicles (or the footpath of such a highway) and it would not exceed one metre in height (from ground level);" We have a train line running about 3-4m away from our rear fence, which is when I wondered if that too would mean that we need planning permission to build the wall considering it to be treated as a vehicle? It is not like a party wall per se but a retaining structure falling well within our property boundaries. In addition, I am not clear on the definition of ground level, which if it is the house level, then the retaining wall will be flush at that level so not breaching the 1m limit but if the ground level is considered to be the base of the structure, then it will be 1.5m from foundation level.

Can someone advise if we need to seek planning permission for this work?

 

[oldbutnotdead]

Some pics or a sketch of the layout would be handy. AFAIK a railway is not legally defined as a highway. The rest of the do depends on the relative levels of everything & their proximity to each other. Retaining walls are tricky things, best getting some expert involvement on the design (like a structural engineer)

 

[s1977]

Hello

Thank you for your advice. I have now uploaded some photos of the dug out trench for the foundation. Hope these help clarify it further.

We bought this property last year and the garden needs doing, so getting it even and flat is our foremost priority but we were a bit worried that we will need to go through the process of planning and approvals from the council, which will delay it further. Anyway like you indicated, we already have a structural engineer's report detailing load and other calculations but they are for a block based wall. Having enquired for quotes on such a wall seems quite expensive here, so was evaluating gabions instead due to their simplicity.

 

[oldbutnotdead]

Presumably you're planning on building up the bit of garden between fence and wall? And also presumably the train tracks are the other side of that fence- are the tracks the other side of those trees? (In which case ignore) or between your fence and the trees (will your filled in garden be lower or higher that the trackbed).
Have a look at Network Rails FAQs, sure there was some stuff in there about groundworks near tracks.
Fairly sure you can ignore planners, why did you not go back to SE and get them to verify your gabion structure?
Problem you've got is if any failure of your structure could impact the rail tracks you'd be all on your own for liability...

 

[s1977]

Hello
- Yes, we are planning on building up the bit of garden between the fence and the current waist height wall. That wall will be removed as part of the building and the plan was for the bricks to be recovered and used in the gabions.
- The train tracks are indeed behind the fence and trees. The trees are behind the fence.
- Our garden level will be raised and above the rail trackbed.
- I will check the Network Rail FAQs as well.
- I have already asked my SE for a gabion wall design. He's stuck currently due to COVID-19 as his family member is at high risk. He thinks we should be ok with using the gabions, but he is working out how to support the fence posts to the gabions as the posts will be quite long to be at the same level over ground once the garden is raised.
- Yes, I agree on the failure of the structure and impact on rail tracks. However I thought that the gabions would actually be progressively compacted over time and the vibration would actually help in compaction. Moreover, I am thinking of increasing the fence side face of the gabions to 4mm wire thick to ensure any chance of bulging is reduced as the remaining sides will be under ground.