60 - 80 cm platform for terrace made of washed concrete slabs

Hello everyone,

I am currently looking for a solution to expand my existing terrace at the campsite, but since I am a layperson and unsure whether this makes sense, I need some advice from experts.

Currently, I only have a size of 1.5m x 2.5m, and my plan is to expand it to 2.5m x 2.5m.
To achieve the new 1m x 2.5m, a platform about 0.6m - 0.8m high is necessary so that I am on the same level as the existing part. I still have a lot of [Waschenbetonplatten] 0.5m x 0.5m lying around and wanted to build the platform out of these and then cover the area with gravel and slabs.

In detail, I would stack 2 rows of 5 slabs each and build them together with mortar staggered until I reach the height.

Now the question to the experts:
Can this work and hold long-term? What else do I need to consider? Frost protection?

Thanks in advance

Best regards

Hello Maik0018

I don't quite understand your plan.
You want to extend the terrace. Good. For that, you need to retain between 60 and 80 cm in height? Is that correct? You have 50 x 50 cm exposed concrete slabs for this.
Do you want to stack the 'exposed concrete slabs until you reach 60 cm in height? The exposed concrete slabs are 5 cm thick. You would have to stack 10 slabs on top of each other to reach that height.
I would use L-shaped stones. For 60 cm height retention 80 cm stones and for 80 cm height 100 cm stones. You have to keep in mind that at that height of retaining, considerable pressure builds up, which will slowly but surely push the slabs away from you.
Maybe you have a bit more space and if you want to use the exposed concrete slabs, I would approach it as follows:
At a distance of 50 cm from the terrace, you dig a trench 50-60 cm deep (frost line), fill it with 30-40 cm RCL and compact it thoroughly. Then you take tamped concrete (earth-moist concrete), pour it in and tamp it properly with, for example, a wooden beam. You will notice when it is good. On top of that, you set the exposed concrete slabs upright (the 50 cm upwards). This all around. Then, when after three to four days the concrete is reasonably firm, at the edge of the later terrace you make a small formwork and towards the terrace fill 30 cm again with RCL and compact it. On top of that, concrete and the slabs, which you have to place so that you reach the final height. After a few days remove the formwork and fill the gap with, for example, soil. That then withstands the pressure and you only spend little money.
I hope I was able to write it understandably in short. It is actually quite simple but hard to explain.

Steven

Hello

I forgot: The exposed aggregate concrete slabs must of course be set in concrete. That is, place concrete about 15cm high at a 90° angle from the ground against the slab. Otherwise, it will tip over.

Steven

Yes, that’s roughly my plan. I have attached a picture of the current status. 1 is the existing area and 2 is the expansion area, which should be raised to the level of 1. For this, I want to use the concrete slabs to build the platform in order to reach the height.

What if I don’t set up the 10 blocks individually and mix them with mortar, but instead build them offset with mortar and thus create only one complete block?

Unfortunately, I don’t have much leeway, so your option with the annex is out.

Or would it perhaps be better to build a wooden platform at 2 and then install a WPC terrace afterwards?

Best regards