ᐅ Covered Basement Entrance for Terrace Extension. How to Construct?

Hello everyone,

I would like to expand my terrace, which would require covering part of the basement stairway.
With the terrace extension, there would also be a height difference of about 30cm (12 inches) to level out, so the covering needs to be load-bearing.

Do you have any ideas on how this could be achieved?
I was thinking maybe using formwork from below and then pouring a concrete slab in 2-3 stages?
And somehow working with lintels and steel beams? I find the attachment to the house challenging due to the 18cm (7-inch) external thermal insulation system (ETICS).

What is the best way to do something like this?
I tried to illustrate it in 3 pictures

What kind of surface does the current terrace have?
Do you want a complete replacement or just a patch?
For a full replacement, I would use decking boards and build a beam frame underneath the stairs area.
If you add a slab, there will probably be a permanent crack at the joint.

Is there a plan for the staircase / basement? Ceiling height?

Concrete walls?

The issue with a densely built-up area that blocks the view is that sooner or later you will have mud and standing water at the lower part of the basement stairs. No light or air can reach there anymore to dry everything out.

So, the basement wall is plain concrete.
The current terrace consists of gravel and concrete slabs.
I plan to completely redo the terrace. However, I would like to keep the existing gravel base because of the effort involved and just patch it up or fill around it.

The basement entrance itself has a drainage system, so the water flows away.
Additionally, since it will be covered, even less water will reach that area. Therefore, I wouldn’t be too concerned about it.

Will the wooden beams also withstand the weather? I mean, I would have to add another 30-40cm (12-16 inches) of fill on top of them. That is quite a significant weight.