Roof sealing flat roof carport

Hello dear construction experts,

I have a small question for you.

We are currently building our new carport on our property. The foundations are done and next week the carpenter will come and set it up.

Now I have a question about the roof sealing.

I have partially read through some forums. Some say you seal it with Schweiß Bahn G200 S4 and then again you read that it would be better with an EPDM membrane?

What is the opinion here in the forum?

Normally an extensive green roof is planned for the roof, which I will not do. Instead, I will put a coarse gravel covering on it.

Regards André

.. both are feasible ... simply a question of money ... with the foil, the decisive factor is the thickness and the foil comes as the entire roof covering ....