Bricks for garage

You are comparing apples to oranges, 24s have about 40% more mass than 17.5s, and therefore also cost nearly 40% more.

The concrete HB blocks are also list prices without discount.

Ok, but for a garage you don't need 24 cm walls if you build with KS. Even the normal exterior walls of the house, except for the basement, are only 17.5...

The OP asked about 24 cm masonry.

And what you said is nonsense. My house has 24 cm exterior and load-bearing interior walls despite highly load-bearing concrete blocks. The garage with a span of 7 m was even supposed to be built with 30 cm by the shell builder.

Ok, if he really wants 24 bricks. But that is undoubtedly dependent on the material, how thick the wall has to be.

well my house is also made of concrete hollow blocks, but can you just lay them like that? or should you already have a bit of experience? the 240mm wall was the suggestion of my architect, the garage is quite large, don’t know if that’s why it should be a 240mm wall... I also thought about aerated concrete, it’s quite easy to work with plan blocks and to process the stones, right? how is it with the price per m²?

Ok, thermal insulation is naturally more given with Ytong or similar stones, and they are also much easier to work with than KS. KS is also very heavy; by hand (without a crane) I would process max. 17.5 x 50 x 25 cm, these already weigh just over 30 kg. The advantage of KS lies in soundproofing, which is not so important for the garage, and that you can more easily attach something to the wall, whereas with Ytong you might need special anchors. I had never done masonry before and have now built a few KS walls (e.g., shower partition). Once the first row is plumb, you can build up the rest almost without a spirit level. Mortar on it and just by the weight, the very precise stones already press firmly on the one below.