Building a single-family house with a granny flat - seeking recommendations

Hello, we have finally acquired a sufficiently large plot of land and are now planning to build a single-family house with a granny flat (like a multi-generational house). Since we are both working and have little time, we do not want to search for electricians, shell construction companies, etc. ourselves and therefore want to build turnkey. Soon we have appointments with 2-3 construction companies to get advice. The most competent one will be chosen. We are not in a hurry with the construction, theoretically we could also move in only in 2-3 years, but we keep encountering the question: Prefabricated house? Timber frame construction? Solid house?

With wood, we have concerns that it offers too little sound insulation. Especially due to living together with the parents (separate granny flat), this would be important. And that it might mold, since we live only 200m from a river, and the groundwater might also rise quickly.

Are there any other tips that we absolutely should consider? We have already sketched/designed plans (fully basemented, separate granny flat about 85-90 sqm downstairs for the parents, 60 sqm kitchen/dining room downstairs for us, 130-150 sqm upstairs for us, possibly bay window and gallery between 1st/2nd floor).

We have already sketched/designed plans etc. (fully basement, separate granny flat approx. 85-90 sqm downstairs for parents, 60 sqm kitchen/dining room downstairs for us, 130-150 sqm upstairs for us, possibly bay window and gallery between 1st/2nd floor).

Then show them. The description sounds rather atypical for what the draftsman of the general contractor is good enough for. Plan with an architect; the apparent extra cost pays off.

Soon we have appointments with 2-3 construction companies to get advice. The most competent one will be chosen. We [...] keep running into the question: prefab house? timber frame construction? solid house?

How can you reliably identify the most competent of three contractors when you are still fundamentally undecided?

Since we are employed and have little time, we do not want to search for the electricians, shell construction companies, etc. all by ourselves and therefore want to build turnkey

Turnkey

The most competent one will be chosen

Sales talks

can theoretically move in only in 2-3 years,

Commitment interest rates

With wood, we have concerns that they provide too little sound insulation.

Sound insulation wood frame construction solid Ytong

And that they might possibly mold, since we live only 200m from a river,

Ventilation systems ..... I'll say it briefly: a lot of ignorance. Best to read around on the mentioned topics here over the next week.

We have already sketched/designed plans etc. (fully basemented, separate granny flat approx. 85-90sqm downstairs for parents, 60sqm kitchen/dining room downstairs for us, 130-150sqm upstairs for us, possibly bay window and gallery between 1st/2nd floor).

There is a floor plan discussion forum here!

Thank you for the suggestions. I will read up a bit over the next weeks/months. I have created a thread for the floor plans:

Correct, I wrote turnkey. Provision interest is initially irrelevant. I will read up on Ytong and ventilation systems.