Hello - I am planning to renovate and partially extend an older house. I want to raise the ceiling height from approximately 3 m to 3.5 m (partly to install taller windows, partly to achieve better proportions in a new larger room). Since the house, which is shaped like a long building with an unbroken gable roof, will not only be lengthened but also widened, perhaps the current roof trusses cannot be reused. What can be estimated about the construction cost specifically for 1) removing a roof including tiles, trusses, etc., on the house approximately 180 m2 and 2) (when the house is widened) building a new mansard roof for the new house area approximately 240m2 (excluding tile material as existing tiles and available stock are used)? There should be no windows or similar in the roof, and the attic should remain for storage only. I know it's very expensive, risky, etc., and I would need more number-based estimates. 