ᐅ Formwork for Strip Foundation of Garden Wall

Created on: 16 Jun 2022 15:39
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Sedax182
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Sedax182
16 Jun 2022 15:39
Hello community,

I need your advice.
I have started a project in my garden. I want to build a garden wall using formwork blocks.
My original plan was:
Dig 90cm (35 inches) deep, place reinforcement bars, then fill with concrete and finally set the formwork blocks.
So far, so good.
Then I rented an excavator and started digging.
Instead of the planned 30cm (12 inches) width, I now have a trench about 50cm (20 inches) wide (plus or minus 5-10cm).
I now have a few options:

1. Use larger reinforcement cages and fill with more concrete. The entire garden will be filled up by 30cm (12 inches) later.

2. Build formwork with shuttering panels, then remove and sell the panels on eBay.

3. Use stay-in-place formwork made of XPS insulation boards.

What do you think?
Or does anyone have a better approach?

I am leaning towards option 2, but I’m unsure.

Regards
In der Ruine16 Jun 2022 15:49
If you are already 90cm (35 inches) deep and then add another 30cm (12 inches) of soil, you will reach 120cm (47 inches). Are you planning to build the Great Wall of China?

With such a generous strip foundation, you don’t need any steel reinforcement.
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Sedax182
16 Jun 2022 15:56
In der Ruine schrieb:

If you’re already 90cm (35 inches) deep and then add another 30cm (12 inches) of soil, you’ll reach 120cm (47 inches). Are you trying to build the Great Wall of China?
With such a substantial strip footing, you don’t need any rebar.

The 30cm (12 inches) of soil is only coming into my garden.
There is a small trench behind it (but a very small one).
The structure should be as follows:
10cm (4 inches) gravel. 80cm (31 inches) concrete.
170cm (67 inches) formwork blocks.
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guckuck2
16 Jun 2022 16:56
You can also simply use larger formwork blocks for the foundation.
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Sedax182
16 Jun 2022 18:58
guckuck2 schrieb:

You can also simply use larger formwork blocks as a foundation.
I think that's a good idea.
I would also go with 36.5 blocks.
How would you build the first row then?
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WilderSueden
16 Jun 2022 20:37
I see several issues here:
1. Trench too wide – either fully fill it with concrete or use compactable backfill on the side. If you want to use a tamping rammer next to the concrete, you would need to widen the trench even more.
2. Trench not as deep as planned – how frost-sensitive is your subsoil? 50cm (20 inches) is already quite deep, and on many soil types that is sufficient. 80cm (31 inches) is usually excessive.

Or do you have another issue that I’m not aware of?