Garage wall thickness

Hello everyone Since my neighbor and I had to demolish our garage at short notice (renovation backlog), I have a question about the wall thickness. There are 2 garages each measuring 6.5m x 3.8m. They previously shared a floor slab/ceiling. Now the whole thing has to be separated floor slab/ceiling. In the old state, about 20 gray aerated concrete blocks were installed all around. Now I am wondering what wall thickness I need for the interior/exterior wall. At the front, back, left side I wanted to use 24, do I also have to go that thick in the middle towards the neighbor or is a slightly smaller thickness sufficient there? Yes, I know, everything could have been clarified beforehand but what’s done is done and can’t be changed anymore. Thanks in advance for your efforts and regards

For garages, you should take 24 cm on the outside; this meets the structural requirements and provides sufficient protection. For the partition wall between garages, 17.5 cm aerated concrete is usually sufficient, as it is not a load-bearing exterior wall but still needs stability and sound insulation, especially if it cannot be separated there.

Think about sound insulation and check with the building authority or structural engineer whether there are any special regulations (e.g., fire protection) in your [Bundesland]. I would avoid simply building thinner blindly – that can quickly become expensive if you get into trouble later.

Thanks already for the answer, in the middle I wanted to take 17.5. Sound insulation towards the house/neighbor's garage via Styrofoam.
Regards Bert