Garden retaining wall made of formwork stones - How to implement?

Hello community,

I want to build a retaining wall in my garden between an existing L-block and a concrete wall. The concrete wall is necessary to have a terrace. The L-blocks were installed by the landscaping contractor, the concrete wall by the house builder.

I now want to construct a wall from formwork blocks (width 17.5) between the L-blocks and the concrete wall (other ideas welcome as well).

The wall would be about 1 - 1.15 meters high, the distance between the L-blocks and the concrete wall is about 1.75. The ground is very hard.

I have the following questions:
Strip foundation: Currently, I have excavated about 2/3 of the length to a depth of 80 cm, the remaining 1/3 is not possible because the base of the L-block is in the "way". I would now put in about 30 cm of lean concrete and on the remaining 50 cm concrete (lost formwork). To prevent the foundation from connecting to the concrete wall, I would make a separation from wood to the concrete wall.

[*
Would you execute the foundation similarly?
[*]Would you recommend reinforcing the foundation? I will definitely incorporate reinforcement to connect the wall and the foundation.
[*]Since the base of the L-block is in the "way," I would simply set on it and then, of course, create a connection between the formwork blocks on the foundation and the formwork blocks on the L-block.
[*]Is drainage necessary? From what I understand, no drainage was installed for the L-blocks and the concrete wall. But I will at least lay a dimpled membrane behind and a sealing slurry.


Wall:
Here I would rely on formwork blocks that I fill with concrete, including reinforcement.


[*]For the formwork blocks, I would go for a width of 17.5 cm, according to the table on "Wall statics for GZ formwork blocks" more than sufficient, right?
[*]I am unsure whether to connect the wall I want to build with the concrete wall and the L-blocks? What do you think?
[LIST]
[*]Pro: Overall higher stability because everything is one structure
[*]Contra: Since all three foundations are executed differently, I am afraid of cracks in my wall


[*]If I want to connect the wall with the concrete wall and L-blocks, I would drill holes in the L-blocks and the concrete wall and create a connection via the reinforcement, right?

Looking forward to your opinions and ideas!

Why didn’t the landscaping gardener do that right away with L-bricks?

I would concrete it. To avoid cracks, with planned joints on both sides.

After L-blocks and concrete wall, now trying to squeeze in a third variant in between? Technically possible if done correctly. Why not do it right away, carefully remove the last L-block, insert a prefabricated corner there, and then place the L-block next to it. You still have to dig deeper, drain water, etc., so an excavator is necessary anyway, unless you want to dig by hand for days.

Hi Alex,

if you want to neatly close the gap between the concrete wall and the L-block, your idea with the shuttering block wall is definitely feasible – but also labor-intensive. Foundation depth and structure are fine so far, but I would reconsider the area where you can't dig deep enough. Building on the foot of the L-block is not ideal, since you don't really know how load-bearing the ground underneath is.

I would definitely do reinforcement in the foundation, especially if you are already working with connecting reinforcement to the wall. The idea of the lost formwork and a wooden partition to the concrete wall sounds reasonable to avoid settlement cracks.

Regarding the wall itself: 17.5 cm width is okay for the height. Personally, I would use movement joints to the existing building structures so that your wall can “work” without ugly cracks later. A rigid connection will not benefit you in this case – on the contrary. Unless you want a statically continuous construction and build the foundations accordingly (but that’s another story).

Drainage: Even if it worked so far without, I would still at least install a studded membrane plus fleece and a water-conducting gravel layer with a drain pipe – better safe than sorry, especially if you have to backfill at the rear.

If you want to do it right and have the tools or time, the solution with a corner + staggered L-block is of course easier, more stable, and faster. But you know yourself: between ideal and reality there is often a very full schedule.

Cheers!

I actually find your planned execution quite well thought out. I would place the connecting irons from the foundation to the formwork stones every 25 cm. Perhaps also bent as an L against the direction of the load if possible.