ᐅ Building a Retaining Wall in the Garden: Formwork Blocks or L-Shaped Blocks?

In the garden, we need to build a retaining wall along 20 meters (65.6 feet). It will have a height of 1-1.2 meters (3.3-3.9 feet) and must hold back the soil on the property. It will only be supporting the garden. No road or building needs to be supported.

1) Which type of wall is more suitable? What are the advantages and disadvantages of a retaining wall with L-shaped blocks versus formwork blocks that are filled with concrete?

2) How should the foundation be prepared? Should it be gravel or a strip concrete foundation (how deep)?

3) What is the approximate cost per linear meter? Does anyone have relatively recent experience?

Doing it yourself or hiring a contractor?
L-shaped concrete blocks of this size can only be moved with an excavator. A concrete block wall can also be built as a DIY project. For the L-shaped blocks, the landscape gardener at the neighbor’s property just placed a small amount of concrete underneath without a proper foundation. I would recommend frost-resistant foundations for the concrete blocks, with the bottom 40cm (16 inches) gravel and the rest with concrete.

We supported it with L-shaped retaining blocks.
Concrete strip footings were used, and I believe they were between 0.8 and 1 meter (0.9 and 3.3 feet) deep.

We had this done in summer 2022 and paid a total of €280 per linear meter (approximately $315 per linear yard) for 1.55 meters (5 feet) high angle supports.

WilderSueden schrieb:

Do it yourself or hire someone?

That also depends on the heavy equipment involved. I don’t feel confident setting L-shaped retaining wall blocks. But I can handle building a formwork wall.

WilderSueden schrieb:

For the L-blocks, the landscaping contractor at the neighbor’s place just put a bit of concrete underneath without any proper foundation.

I imagine that would be difficult since the neighbor excavated quite steeply at the property boundary and didn’t secure it. I’m afraid I won’t be able to avoid a concrete foundation for the L-blocks as well.

Yaso2.0 schrieb:

We supported with L-shaped blocks,
working with strip concrete foundations about 0.8 to 1 meter (31 to 39 inches) deep, if I remember correctly.

We had that done in summer 2022 and paid a net price of 280€ per linear meter (about 85 USD per linear foot) for 1.55 meter (5 feet) high retaining blocks, all inclusive.

Which federal state? I was somewhat expecting higher costs.

BiffBiff schrieb:

Which federal state? I was partially expecting worse.

Bremen, near the border with Lower Saxony. However, I have to mention that we bought the blocks ourselves from the supplier after deciding between formwork blocks and L-shaped blocks and checking prices. The landscaping contractor then installed them, which is how the “cheap” cost of 280€ was reached.

We also had an offer from another regional landscaping contractor, which was around 420€ per linear meter.

BiffBiff schrieb:

I imagine it’s difficult since the neighbor has excavated quite steeply right from the property line and hasn’t reinforced it. I’m afraid I won’t be able to avoid a concrete foundation, even with L-shaped retaining blocks.

It’s best to coordinate with your neighbor. If both of you are significantly altering the original ground level, it also makes sense to share the costs and reinforce it just once.