Houses without basements: Storage space, hobby basement?

Yes, and of all people, I received an interesting approach from you:

Im OG haben wir auch noch einen kleinen Abstellraum (ca 2,5m²).

For example, I hadn’t thought of providing a storage room on the upper floor. If it is under the high side of the shed roof, you can equip it with shelves all the way up to the roof or perhaps cleverly insert a second mini-level there. That’s simply about 6 cubic meters.

So always stay smooth

Edit:
Just as valuable to me is a "We were like that too and still managed it" post.

1. Dispose of as much as possible. 2. Provide accordingly large cabinets in the bedroom/dressing room, living room, study (wherever)... for winter/summer clothes, Christmas decorations, children's toys, etc., and/or plan additional rooms. 3. Larger garden shed for everything needed outside + possibly strollers, vehicles of all kinds, etc... I really can't think of anything else for the life of me. Oh yes, something else comes to mind: I recently saw an earth cellar used as a basement replacement. Whether you want something like that is up to each individual.

I have to say that I also like to keep things very much, unlike my wife, who is negatively influenced by her mother’s hoarding tendencies.

We have installed some half-height shelves in the attic (hip roof as a truss construction) and stored a lot there. In the end, there was more space upstairs than I originally thought.
Some other items that cannot withstand the temperature fluctuations in the cold attic we stored in the HAR or utility room on shelves. We also have a wall unit in the guest/office room with plenty of storage space for folders, vases, office supplies, photo albums, and other odds and ends.
In our wardrobe, I built a built-in closet myself using Ikea interiors and doors and side panels from the hardware store. There is also still quite a bit of space at the top.

What I have found problematic so far is tools and building materials. There is always something to do in a house and going through the floor hatch with tools/building materials is inconvenient. In addition, we also had bicycles and garden tools, which previously had no place and were only relocated afterward.
Now that our 9-meter-long large garage is built, there is space for everything that previously had no proper place.

Since a garage/carport is not planned with you, you would have to see about placing a larger equipment or garden shed on the property.
If the outdoor storage spaces are planned for later and you are looking for a temporary solution, a used construction container could also be an option in case of emergency, which can be sold again later.

Shed or garden house will definitely be built. Hopefully it will be a bit bigger, but it is of course possibly damp and therefore only suitable for the usual stuff you keep in such a garden house.

Garage or carport is not coming for the reason that the development plan does not allow it and the plot is very small. We would have to put the garage in the garden. Unfortunately, the most sensible spot right next to the house is not allowed to be built on.

5-year rule: what you haven't used or touched in the last 5 years, you won't touch for the next 50 years either. So get rid of it!

Of course, you can also make it a 2-year rule

I would store the stroller (and all textiles) in a dry place, meaning inside the house. We once had the situation with the older child where the buggy was kept in the garage, and the cushion eventually developed mold spores because of the moisture.

We ourselves are not collectors, but with 3 children quite a lot accumulates. Currently, we have a basement. However, due to high groundwater pressure and because we don’t like going to the basement, we decided against a basement when building the new house.

We have planned a 12 sqm utility room including technology with enough space for a large cabinet or shelf (about 2.50m of storage space) for shoes, sports bags, muddy and rain clothes.
The wardrobe will also have a very large shoe cabinet and many hooks for jackets etc.
In addition, we have a pantry of over 4 sqm and a broom closet under the stairs.
And the living room will get a large built-in wall unit 'sooner or later.'

Upstairs there is also a built-in cupboard with 2 sqm for cleaning supplies and toilet paper stock etc.
A hobby room upstairs, which also functions as a guest room and office with 18 sqm.
In the bedroom, a 3m wall for a cupboard in addition to the walk-in closet.
In the attic, a storage room with 20 sqm floor area. However, this is completely in the slope without a knee wall, so ultimately not quite that much. Everything related to decoration and children’s clothes that are saved will go there.

Additionally, we have planned a double garage for one car. The second car is parked outside. The garage will then hold 5 bicycles, a workbench, and shelves.
For later, a carport with a tool shed is planned behind the garage for firewood, a trailer, garden toys, and equipment.

That sounds like an incredible amount. I’m convinced it will be more than enough.