Questions about costs and notary contract regarding the demolition of a freestanding terrace

Hello,

I have just received my notary contract for the purchase of a plot of land. The neighbor (not the seller of my plot, but the father of the seller) has a garage with a gable roof. Attached to this garage is a small outbuilding that was built on the boundary (about 2m and on the boundary about 3.5m). The roof of the outbuilding is a shed roof and covers both the outbuilding and then extends onto my property, where it serves as a covered outdoor area (about 3.5mx2.5m). The drainage is carried out over my property (infiltrates).
I want to dismantle the covered outdoor area later. The notary contract states:
In the event of dismantling the aforementioned covered outdoor area, the buyer undertakes to carry this out properly. In this context, no impairments or damages to the outbuilding shall occur.

The roof of the outbuilding will certainly be damaged during the dismantling. I am also unclear who must take care of the drainage for the then shorter roof.
To be honest, I am not an expert and have no idea what costs will be incurred, whether it is 100 €, 1000 € or more. Maybe you can give me some tips here.

I would like to include in the notary contract that the costs for the damage repair be shared and the costs for the drainage be entirely borne by the neighbor.

Depending on how many interested parties there are, the seller will not respond to it. Currently, everything is set, so why should the seller financially harm his family?

You are paying a lot for the notary. Discuss this with him. "No impairment" and the demolition of the drainage are contradictory and need to be clarified. Best to bring a photo. (Is the outbuilding perhaps only the garage?)

I have attached a picture, maybe that will make it clearer. The border runs exactly along the wall where the ladder is leaning.

So I would understand it that in case of the demolition of the shelter you have to make sure that his buildings are not affected. That would mainly mean that you have to have the roof professionally shortened accordingly. The drainage needs to be discussed, although basically he would have to drain on his property. But if there is enough space, you could also put a water tank there and use his water for the garden.

Everything else strongly depends on how sought-after the property is. But cost sharing will be rather difficult to implement if you are not the only interested party and they are under pressure to sell.

I still don't understand. What does professional mean - it is not specified in detail. For example, if I have the roof shortened and install a plastic gutter, what happens if the owner says they are not satisfied with it?

Since I am not from the construction field: is there a way to simply cut off the roof with a grinder and then install a gutter? Who is best to ask about this?