New construction after triplet birth. Looking forward to your ideas.

A gable-side extension would be significantly cheaper in terms of effort - but for that, we would first need to know what "is possible".

I thought the same today: on the ground floor, design the office as a passage to an extension at the top of the plan. Then in the extension, the parents' wing, preferably also with a small shower bathroom. What fits in there... upstairs the former bedroom as a hallway including a large storage area under the roof leading to two children's rooms... so that is probably the most economical alternative.

The most expensive option is probably if you do a roof raising, i.e., a repositioning of the roof truss including a higher ridge, so that the staircase can be extended into the attic where additional rooms can be created.

if you do a roof elevation, that is, a relocation of the roof truss including a higher knee wall,

I also don’t see that here (insider knowledge of those who opened the PDF): the eaves height has increased by 50 cm between the old and new version. Currently, there is apparently 0 cm knee wall – the height lines and the knee wall at least suggest this interpretation – which in turn indicates that the old eaves height did not leave significant "space." So if you can only insert a 50 cm knee wall, the effort of raising it is certainly not worth it.

Wow, triplets right away! Now that's life in the house. You should first consider whether each child really gets their own room, or if you want to work with shared sleeping spaces. Especially since there are 3 boys, you could consider one room with beds (separated somewhat with room dividers) and one room for playing/gaming and a small sofa area. Boys are usually more tolerant than girls when it comes to sharing space. But it's a matter of taste. Otherwise, I would also advocate for extending the gable towards the garden. That looks most sensible.

Hello,
thank you again for your suggestions. Now we had a few hours and have made some progress in our planning.
A gable-end extension is now our absolute favorite. An additional storey is actually not possible due to the max eaves height.
Additionally, we want to insert a captain's gable. On the ground floor, it should create more brightness and space (and partially fulfill my wife's wish for a conservatory). Upstairs, the additional gable allows us to take a bit from the middle room and turn it into a corridor. This way, we could realize 6 bedrooms upstairs. I’ve attached a sketch (where you can also see that Sketch Up and I are not best friends yet )
The only question we currently have is how to make good use of the space in the living room. Somehow we haven’t come up with a nice room layout yet... Do you maybe have any ideas?
I’ve also attached my idea, but something is missing. It’s practical, but not yet nice?!

Gable-side is a good decision

Take graph paper, draw in the furniture you would buy, and go through your daily routine again and again. Write to the user Arifas. She has 5 children and might see something we don’t recognize.