Garage connected to the house - Where is the roof support attached?

Preliminary information:
Urban villa (built in 2019)
36.5 cm Poroton without insulation with silicone resin plaster

Garage (built later as own work)
6.50 m * 9 m
24.5 cm Poroton
1 interior wall 11.5 Poroton
Wood flat roof
Access to the house

The base slab will be made directly for both objects by the general contractor
Sketch of the garage’s location to the house is attached.

If we add the garage later, we had always thought of 4 walls so far.
Now, however, it has been suggested to us to build the garage on the house without a separate wall.
I would also prefer this option, since you would have at least 25 cm more space inside.
Now to the question that occupies me:

Where/how is the roof fastened/supported on the house side?

Is the purlin left out and the rafters attached to the masonry with joist hangers?
Is that sufficient to carry the load?

Or is there the possibility to create internal joist hangers in the house wall by cutting out the masonry bricks, so that the rafters then rest inside the house wall? (but there would have to be quite a few. That wouldn’t look good before building the garage, I think)

What other possibilities are there?
I won’t just be able to screw a purlin to the house with “arm-thick” screws, right?

Yes, we will also discuss this with an architect or general contractor, but I like to go into such a conversation with some prior knowledge before I am sold a pig in a poke.

Thanks for your information.

Support is provided on the fourth garage wall. The house must be insulated in the area of the garage. Therefore, both walls run next to each other. Insulation in between.

The point is possibly not to create a fourth wall. We have no [WDVS], i.e. the house is neither more nor less insulated at the spot where the garage will eventually be.

Energetically, the fourth wall, meaning a double wall, does not bring any benefit. Firstly, no insulation is lost, and secondly, the garage still serves as a buffer zone (even if not considered in the energy saving ordinance).

Without the fourth wall and without anchoring in the house wall, nearly 9m must be spanned there without the intermediate wall. That would become quite thick and not exactly cheap.

It is usual, as with covered terraces or balconies, to anchor the purlin along the house wall in the wall. I don’t know how the static structure works with Poroton. It should be possible without problems in the intermediate ceiling if the height fits. The screws don’t have to be as thick as an arm, since the lever arm is quite short.

As an alternative to the continuous wall, you could also support the purlin halfway with a post (wood, steel, or stone/concrete) without fastening it to the house wall. Then you only have to span 4.5m, which is much easier.

In the version without fastening to the house wall, however, I would execute the connection of the flat roof to the house wall openly with overlapping sheet metal/copper profile and not by means of a firmly attached sealing membrane on a rail.

Thank you very much for the response.

Strictly speaking, it would then be "only" 7 meters for an anchored purlin, because at the back 2 meters of masonry are again freely available for support.
Unfortunately, we cannot access the intermediate ceiling. The garage is only allowed to be 3 meters high on average, and the intermediate ceiling is... yes, at 3 meters.

Ok, how the anchoring looks statically with Poroton would of course have to be clarified, just like all other static questions.

I was once advised to pour a ring beam around the garage with Halfenschienen, which rests in the middle on a reinforced concrete column on the house side and is connected to the masonry of the house. In this case, the purlins can be completely omitted and the rafters can be attached to the Halfenschienen.

What do you think of this statement?

I know a house where the shed roof of the extension (workshop) rests on 2-3 wooden posts on the side of the house, which bear the weight. For stabilization, the ridge (would be the purlin in your case) was additionally fixed with wall-through screws (of course, this does not work in every case...).