Upper floor extension of residential settlement house

The ground floor is inhabited; the conversion measures should not be noticeable there. The wish was for a transverse gable (4 m) starting at the ridge to the south, over the raised terrace on the right side of the house. The cellar external staircase comes up on the left side. The south side has two rooms. In the attic a bedroom.

We have submitted a preliminary drawing; the building authority requests the gable in the middle. Use of the attic is not possible. There is still a chimney in the middle of the house.

We have about 48m2 of living space on the upper floor; what is more cost-effective: to add a "non-fitting" independent concrete box or two north-south dormers with a max. of 3 m.

We would be grateful for rough cost estimates. The roof structure must be stabilized and insulated: collar beam roof.

We would be very happy about ideas.

We would be grateful for rough cost estimates..

Somewhere between €20,000 and €150,000, but it can also be more expensive........:cool:

Then I'll ask differently: which could be cheaper, an extension made of timber frame construction or brick.

Or rather, who has ever expanded a settlement house with an L-shaped extension. We only wanted one more room on the upper floor, so we had the (rejected) idea of sleeping in the attic. Now we are considering building an extension of about 4 x 4 m...

Attached is the drawing of our rejected desired modification