Seal garage against house wall

We are possibly planning to build a garage on the east side, 540x300 cm, which is to be placed directly against the house wall with about 2 cm clearance. What are the options for sealing, both on top and on the sides? Drilling into the facade is out of the question for me. I am afraid that mold might develop in between.
Regards

If it forms, so what. We have placed a concrete garage from Rekers, measuring 6 by 3, against the unplastered Ytong wall on the east side. Then it was plastered. The remaining gap is sealed vertically with a permanently elastic jointing using MS polymer compound. A angle iron was mounted on top, bolted into the wall and the garage roof, additionally sealed with MS polymer. Moisture can of course still get into the gap from below, but that doesn't matter to the wall and the concrete.

The building is already plastered, so I wanted to avoid mechanical fastening.

Then you glue the angle bracket pure without screws. MS Polymer sticks like hell, is elastic, seawater resistant, UV resistant, and typical for a poly....chemically insanely stable. The bolts are actually unnecessary. And it sticks devilishly well to metal and to stone or concrete, also incidentally to the paws and can't be gotten out of the pants by any white giant anymore.