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I’m looking to build a 600mm garden wall to keep a raised garden bed beck back off the side of the house (previous owners though buried weatherboards was a good idea…) I initially had questions about the wall itself, but in thinking it over last night I also have some concerns about the exposed foundations.
Wall will be L shaped, 3m X 1.8m. I also had to dig out 2 trees that were in the bed and too close to the house. I've dug the trench but in doing so to get all the roots out I went about 100mm deeper, thinking it would be good to get more organics away. However I now have 2 concerns.
- 1. the trench actually goes lower than the concrete footing of the patio brick wall (about 15cm) and on the other end a small 3-4 course garden edge wall (under the footing by more than like 20-25cm), and
- 2. I have exposed the concrete around the corner stump for the house. I haven't tried to dig under it or anything and I assume/hope it goes much deeper than 30cm.
I'm not sure if either of these will create 'load' on the wall, or if they might now settle because I've dug away some of the dirt that was next to them. My plan was to fill in about 10cm of dirt (fairly sandy), compact with a plate compacter, then put in 10cm of road base, compact that, then put in the concrete footing, remove the form work and fill the gap around where the form was with the either dirt or left over roadbase.
I then plan to build the wall (questions on that below) and fill on the house side with dirt up to the ground level of the underhouse. (considered doing about 10cm of blue metal on the 'house side' but actually think dirt is better since it'll encourage water to spread rather than creating an area for it to pool by the footing. Garden side I was going to put some blue metal to encourage drainage but no actual agpipe or anything since it should drain fairly freely out the bottom of the bed?
As for the wall itself, the house is weatherboard from the 1920s and has lots of brick around other gardens and paths, so could do a 7-8course English bond brick wall on a concrete footer, on top of compacted road base. However, I'm wondering if it would be better to do something more like 2 courses of concrete retaining wall blocks (like adbri Versawall) on compacted road base (seems concrete footing is optional), then capped with a header row of bricks so the unburied part matches.
- 3. Any advice on which of brick or concrete blocks is more suitable or if it doesn't matter? It won't be very visible so aesthetics less important (I've not laid bricks before but was excited to learn)
- 4. Do I even need the roadbase? I see the other footings were just on the fairly sandy soil. I know I would have to compact it if I put it back in, and maybe now since I've dug it out the roadbase would be worth doing?
- 5. If I do a concrete footer this size (500mm wide, 3m long, then 1.7m long on the other side), does it need reo, mesh and/or contraction joints? Do I need vertical reo into the wall or can I just mortar them? The bricks I would use are solid (was planning to use reclaimed to match since not much price difference). I read conflicting things about if these are optional or required.
- 6. Should I fill in on the house side with dirt or do I need to use something else? I can hand tamp that but feels like if it needs any real support for that house stump on the corner then me tamping isn't going to do much of anything
- 7. Assuming I can build close to the existing brick walls, how do I get around the bits of concrete from the old footing that stick out? Should I cut bricks to go around that? Do I leave an air gap? Do I just fill it with a bit more mortar? Do I need to drill a reo into each end (I'd personally prefer them not connected probably, esp the patio as I don't want to compromise that wall at all and no clue how old/brittle it is.
A few photos uploaded, happy to share more if helpful. Keen to learn and try figure this out, but if you feel this is risking causing a bigger issue please shout and let me know who I should get in to take it over.
Thank you all, I've read so many helpful threads here!
