Renovating the roof or expanding the attic: help, tips, and advice

Hello everyone,

as already mentioned in the thread, it is about the expansion/renovation of the attic.
Since I am still at the very beginning of the project, I wanted to get some information beforehand.
About the house:
Two-family house built in 1975 (continuously modernized, except for the roof)
Floor area 12.50 m x 10.50 m
Roof currently covered with corrugated sheets, no roof insulation (insulation in the form of approx. 5 cm thick panels laid on the concrete slab)
Floor in raw condition (concrete slab, without screed, no water or electrical lines)
Due to family growth, living space is to be gained, i.e. the attic is to be converted.
The attic should contain 1 master bedroom, 2 children's bedrooms, 1 WC and a storage room.
What I would of course be interested in:

[*]Reuse old roof truss elements? (Roof is tight and all beams are in good condition)
[*]Solid or drywall partition walls?
[*]Costs for fully insulated roof truss, the two children's rooms should have dormers, otherwise only normal roof windows (2 pieces), glazed tiles?
[*]Is funding possible/sensible?

Maybe someone here is planning or has already completed similar construction work and can give me a rough overview of what the whole thing might cost us.
Two appointments for a site inspection have been arranged, but it will take a little longer as I am currently only at home on weekends due to work.
Of course, I do not want to go into the appointments completely unprepared.
I understand that no exact statements about costs can be made here, but at least a rough framework.

Thank you very much in advance.

Best regards

Stephan

0. Is one allowed to do what one can?
Does the building volume / floor area ratio allow this attic conversion?

1. Reuse old roof truss elements? (Roof is tight and all beams are in good condition)

Are supports included - if so, can they remain as they are, i.e., are they "integrable" instead of disturbing?

2. Solid or drywall partition walls?

Rather drywall, this is easier in terms of statics, easier to build, and the roof has supported itself so far without partition walls.

the two children's rooms should have bay windows, otherwise only normal roof windows (2 pieces)

Do you mean dormers or gable dormers?

4. Funding possible / reasonable?

Conceivable. Attic conversion instead of new building land demand is sometimes funded. Roof modernization with regard to thermal insulation as well.

Hello 11ant,

thank you for your reply.
The children's rooms are to receive dormers (I already changed this shortly after creating the thread).
The roof structure has supports which could also be integrated.
During house construction/roof structure construction, a later use of the attic as living space was already planned and the supports were adjusted accordingly.
The building mass ratio/floor area ratio should not be a problem, as the plot is 1200 m2 in size.

Best regards

Stephan