ᐅ Terrace in Split on a Concrete Slab

Hello everyone,

Here is my third question regarding the construction of my new terrace:

Basically, I would like to install the surface with gravel, possibly partially bound, but this is not yet finalized. It is also undecided whether to use concrete slabs, porcelain stoneware, or natural stone slabs.

There is already a base slab, or it will be extended, but I plan to raise the level significantly higher than it was originally. From the top edge of the base slab to the top edge of the terrace, the height difference is about 25cm (10 inches).
Assuming I use 5cm (2 inches) thick slabs as the surface, 5cm (2 inches) of gravel, this would leave 15cm (6 inches) of crushed stone on top of the base slab.

Question 1:
Is this acceptable?

Question 2:
So far, there has been no drainage on the base slab. I also assume that the base slab itself has no slope, and I would do it the same way again (since it has been fine so far). Does it make sense to create a slope with the crushed stone first, then add drainage membrane, and finally the gravel, or is that unnecessary?

Question 3:
I would prefer to work without an edging stone; what is the best approach for this? (The base slab is 10cm (4 inches) wider than the terrace).

Thanks in advance for your input!

My opinion on this: if the bottom is solid and waterproof, it forces the top to be the same. Otherwise, you will have issues with frost because the water cannot drain properly.

WilderSueden schrieb:

My opinion on this: if the base is solid and waterproof, the top must be the same. Otherwise, you will have issues with frost damage because the water cannot drain properly.

What exactly does that mean as a recommendation?

That would then be mortar with a waterproof joint. I’m actually not a fan of that at all, but if there’s a concrete slab 15cm (6 inches) underneath... Although with the concrete slab, a wooden deck would actually be more suitable than paving or slabs.

Why do you install a concrete slab if you plan to use gravel?
As mentioned before, you need to make your patio waterproof now and ideally fully cover it. Heavy rain combined with wind can cause significant problems quite quickly.

Covering is not necessary, but an appropriate slope and height difference are. According to standard guidelines, without a gutter this means a height difference of 15cm (6 inches), and with a gutter about 5cm (2 inches).

In heavy rain, infiltration plays almost no role since the rainfall exceeds the infiltration capacity by far. Much more important is ensuring that no water from the surrounding terrain can flow onto the terrace.