How to build retaining wall against fence?

[nmd19]

Hello all! 

We are planning to level our backyard which is about 600mm high. We were recommended to add a retaining wall against our fence to ensure it does not collapse. Would we need to add additional posts into the ground to add the sleepers or can we drill these directly to our existing posts? Any other suggestions would be greatly appreciated.

Thank you!

[Jewelleryrescue]

Hi @nmd19 

Your advice not  to use  your fence posts in your retaining wall build as they could  collapse is spot on

I highly recommend you build an independant retaining wall off your fence because one day that fence will need  replacing and ripped out and  that will destroy your retaining wall too   I would hate for you to face  that problem a double wammy with the fence rebuild too.

Build it in at least 50mm off the fence posts.  Your 600mm height is  right on the limit of many council retaining walls limit  for building  with no DP and engineering design It would  be wise to add Ag drain along it  to reduce water pressure if it occurs in heavy  rains. and a gravel fill over the Ag line,

Build it out of treated pine 100mm posts  and 200x 50mm sleepers  is  cheapest option USE H4 timber for longer life span. There are landscaping blocks your can stack and make it, but they are expensive at $13 ea approx. A near forever  wall is  brick work made  ot Besser Blocks are $4  ea but  this  will need  cement footing 300 by 300.

Well  A big  job  but  your place will look  great hang in tthere

[JacobZ]

Hi @nmd19,

A warm welcome to the Bunnings Workshop community and thank you for your question about building a retaining wall near your fence.

Your retaining wall should be constructed separately from the fence as @Jewelleryrescue has already pointed out.

I'd suggest you start by reaching out to your local council to see if there are any setback requirements for structures. Oftentimes, there are rules on how close to a fence line structures can be built, so it is worth checking before deciding on a location

In terms of materials, timber sleepers are the most cost-effective option. There are also concrete sleepers and retaining blocks which you should consider.

Check out the Retain-It Posts and Ridgi Posts, they are great options for anchoring sleeper retaining walls. There are options for different thickness sleepers and for different height retaining walls. The 1.1m and 1.2m high options are designed for 3 sleeper-high walls, which is what you'd be looking at to retain 600mm.

For an 1100mm post, you'll need a hole 300mm in diameter and 600mm deep. These holes can be dug using a Post Hole Digger, which can be hired through your local Bunnings' Hire Shop. 

Once dug, you'll want to add 100mm of drainage gravel at the bottom for the posts to sit on. You'll then need approximately 3 x 20kg bags of concrete per post.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob