Sealing of floor-to-ceiling windows from the outside

You are allowed to do it. You will just have to sign for it... My parents also don’t have a gutter under the roof. Instead, there is a steeper slope on the terrace. We also have gutters in front of the covered windows (whether fixed or movable). Additionally, there is drainage for the entire terrace area.

Who am I supposed to sign something for?
Our GU finds this sealing "enough."
And nowhere is it mentioned that we have to install a gutter...

With us, I had to sign that if the terrace is built, it will only be installed with a gutter. Since we have a flat exit about 2cm high. Still, no one has the slope away from the terrace and drainage under the slabs is enough.

I'm facing the same situation..... but for me it's individual trades. The window installer pointed it out to me, but said it shouldn't be his responsibility, he told me: either the landscaper or the roofer.

My roofer doesn't do that.

My shell builder wanted to name a partner for that, but I don't know what something like that costs.

So it costs a lot of money, you can easily count on 500 euros per door. For us, it would have been 2500 euros. Doing it yourself only costs you about 300 euros for materials. So you save over 2000! Working time about 6 hours.

It's very simple and if you do it yourself, you'll do it more thoroughly than a company. I can really only recommend doing it yourself.

So it really costs a lot, you can easily calculate 500 euros per door. For us, it would have been 2500 euros. Doing it yourself only costs you about 300 euros in materials. So you save over 2000! Labor time about 6 hours.

It’s very easy and doing it yourself is more thorough than a company. Can really only recommend doing it yourself.

Shall we continue via private message?

the slope away from the terrace and drainage under the slabs is sufficient

In heavy rain events, no.
Do you have a barrier-free/close-to-the-floor lift-and-slide door? Then take a look at the fine print, driving rain and the like are excluded; those things are never 100% tight. I feel considerably more comfortable with a channel, especially since the terrace faces the weather side.
With a roof over it, you could rather speculate about doing without it.

So it costs a lot of money, you can easily calculate 500 euros per door. For us, it would have been 2500 euros. Doing it yourself costs you only about 300 euros for materials. So over 2000 saved! Labor effort about 6 hours.

A bucket of sealing paste costs 50€, the work is a joke. What should cost 2500€ there?