From the highest point (back right fence corner) to the patio is just shy of 2′ in height difference. I’d like to put two short walls in where the blue and red lines are and each would have ~15″ of soil behind it. My plan is to use 6×6 treated lumber.
Dig a foundation trench 6″ deep and fill with 3″ of gravel and tamp it down.
Lay one row of 6×6 and secure with rebar every 4ft. This row will be half under and half above ground.
Lay second row of 6×6 and secure to first row.
This would be the same for both tiers. I’ve read about deadmans but don’t think I need it since each tier is ~1ft. I’m not positive I need drainage either since that area doesn’t get much rainwater cos of the tree, but I will add it anyways, just in case. That area looks fairly dry even after it rains and rainwater slopes down towards the side yard.
This is what I’m picturing, but only two tiers: https://i.imgur.com/RROwqfn.png
I tried to do as much research as possible before asking so hopefully this plan is at least somewhat solid.
I’ve had this area marked out and there is nothing under there except potential tree roots. If I start digging and hit a tree root, what options would I have for working around it? Instead of a 6×6, could I get away with using 4x4s for this?
Any input you can provide is greatly appreciated!