Optimize and expand the floor plan of an existing house

The stable roof itself is quite certainly asbestos and actually needs to be removed.

And even during the dismantling, proper procedures must be followed, which limits the selection to certified companies. Yes, I only mean the corrugated cement roof; given its age, anything other than asbestos would really surprise me.

I am afraid that €80k will not get you very far with the stable expansion. Everything has to be done from scratch. I imagine the attic conversion to be much easier, also in terms of own contribution.

I have been dealing with the planning of old building renovation on two properties for quite some time now. One of them is a former farmhouse with a stable and a barn. To convert this into living space, the cost estimates are around €2000/m2 (+/-10%). The resulting living area then meets new building standards and all technical systems are new. If you take the floor area of the stable and consider whether the attic should also be developed in the stable, that can then be calculated. I think that with the expansion of the attic you will be cheaper. But then not everything is "new". As a concept, the stable could be developed as the "parents' house," i.e. bedroom, bathroom, and maybe a study / relaxation room. In the old house then the children's rooms and living / dining / kitchen. Plus a (glass) transition from one house to the other ... then we quickly come to an investment of €500K +X.