DIY my backyard

Hi all,

My backyard is 14m wide and 5m long and is flat and no slope. There is a 700mm concrete pathway behind my house. Behind this pathway, I am planning to DIY our backyard garden.

This is what I plan to do and wanted to check with you all if there is any issue with this plan, and if I need to take special care of something or am I missing something:
1. 400mm behind the concrete pathway, I plan to install agi pipe across 14m width of my land and close one end of the agi pipe and slope the agi pipe towards the other end connecting to a storm water pipe.
2. 300mm after the agi pipe drain, I will install treated pine retainer wall of 500mm height.
3. Behind the retainer wall, I plan to fill with soil until 1m from the back of the fence. Do I need to do anything further behind the retainer wall for drainage (another set of agi pipes)?
4. Near the fence, I plan to plant trees and bushes to cover the back fence.
5. I will be connecting poly pipes to help with irrigation and connecting electric wires for garden lights.

Thanks,
Rishi

Draw something.
It reads like you have 70m² of backyard and you want to create a 50m² planter box leaving you with 10m² of concrete path and 10m² of backyard.

Hi,

This is what I plan to do. Please help.

Any help would be great. Please provide your suggestion on whether this will affect drainage in my backyard?

Hi Rispar,
Looks like this should work ok. You should always run your ag pipe into a silt pit (300mm should suit) before connecting to existing storm water system. You should also look at an aggi pipe behind the wall and some form of waterproofing and drainage aggregate to protect the wall. I would use galvanised steel posts. Hope this helps a little. Please feel free to ask any questions.

Thanks for your response. Would a stone retaining wall using blocks available from Bunnings be better than going for a timber retaining wall?

Hi Rispar,

Any sort of retaining wall will suffice as long as it is constructed properly.
Not sure if you are looking at link walls or besser/concrete blocks but both have positive and negatives as well as different costs.
The link block walls are very easy to install, don't need a concrete footing in most situations and are permeable. Besser block walls require re-inforced footing, steel work, are harder to lay and will require render or some sort of coating to look decent as well as filling the internal with concrete.
Treated pine timber retaining walls with galvanized posts are the easiest and most cost effective. I always sand the sleepers and bevel the edges then stain them which looks better than just installing the sleepers as is.