How to fix fence that will be lower than land after landscaping?

[Lammy]

Hi team. I'm trying to DIY landscape our new knock down rebuild home. The issue is the existing fence was built with the natural slope, but since our new home is built on a slab, the builder has more or less raised the home. To bring the land 100mm below the slab-line will make parts of the existing fence up to 400mm below the desired finished land level, which won't be great for the fence as it isn't a retaining wall. The fence is about 18m long, but this depth issue evens from the deepest part (400mm) and is not a problem after about 9m.

Ideally we'd like to keep the existing fence, but I'm not sure what options I have other than to build a retaining wall and then attach a new fence on top. What solution would you guys recommend?

Thanks for reading!

[MitchellMc]

Welcome to the Bunnings Workshop community @Lammy. It's sensational to have you join us, and many thanks for your question about raising soil levels.

You’re thinking along the right lines. Once you raise the soil level, that soil has to be retained, and an existing boundary fence can’t do that job. Even at 200 mm, building up against a standard fence will almost certainly lead to rot, movement, or failure over time.

Broadly, you’ve got two realistic options. One is to remove the existing fence, construct a proper retaining wall along the boundary, and then reinstall a new fence on top of the retaining wall. Structurally, this is the cleanest solution, but it does involve a conversation with your neighbour. If their land level is staying lower, they may have concerns about a higher fence line, loss of light, or changes to privacy, so agreement and council rules come into play.

The other option is to keep the existing fence exactly where it is and build a retaining wall fully inside your own property line. That allows you to retain the raised soil without involving the fence at all, but the trade-off is losing some usable yard space where the retaining wall steps in from the boundary. Depending on your council, this may also be the preferred or required approach.

One extra thing to consider is fence height relative to your finished ground level. If your ground ends up 400 mm higher at the fence line, you’ll effectively be standing much closer to the top of the fence, which can create overlooking issues into the neighbour’s yard. That alone is often enough reason to coordinate a retaining wall and fence solution together, rather than treating them as separate elements.

Unfortunately, there isn’t really a third shortcut option here. If the land is going up, something needs to retain it, and the existing fence just isn’t designed for that role.

Please let me know if you have any questions.

Mitchell
 

[Lammy]

Thanks for your response! Do you have any existing projects where a fence is installed above a retaining wall... and what kind of wall is suitable (for say 250-400mm height)? Thanks.

Sorry, and I guess if fence preservation is the priority, could the third option be to just let the land slope down towards the fence line, but put in some drainage and plumb it into the drain-line (which incidentally runs parallel to the fence on that same patch of clay).