Narrow house extension with access to the attic: Retrofit of an elevator

Hello,

my wife and I are currently looking for a way to expand the existing house (3 condominiums) to create more living space for us and the future.

Initial situation: The house with a double garage (see attachment) has 3 condominiums (ceiling height 2.75m). The ground floor (parents-in-law) and the attic with flat roof belong to us. The attic apartment with approx. 100m² would then be intended for us.

Idea: Since an extension of the house was not approved by the building authority, the architect recently suggested the first idea to build an extension where the double garage is, which is about 5m wide (red drawing). The area of the extension would thus be 9x5m. Since the house is about 11m high, the idea was to build an integrated garage on the ground floor, create living space on the 1st floor, and additional living area in the attic with a passage to the existing apartment and enlargement of the balcony. The existing staircase to the attic apartment would be separated. Thus, an independent house would be created through the extension, but connected to the existing one (like an L rotated by 90°). The double garages for the other owners would be built on the other side of the property.

Problems: The house stands on a plinth (1.5m). Therefore, a staircase height of almost 4m would have to be covered from the integrated garage to the 1st floor.

We have already somewhat fixed the layout for ourselves; independent of all the theory, the problem of the stairs and later the possibility of retrofitting an elevator should perhaps be considered.

Ground floor: integrated garage
1st floor: kitchen + pantry, dining room (groceries would not have to be carried far)
Attic: usual living and sleeping area with 2 bathrooms.

Conclusion: We find the idea very interesting, as living space in Frankfurt (Rhine-Main area) is very expensive. I would be happy if you could contribute ideas, especially regarding the staircase issue. I hope this is somewhat understandable.

Many things are possible, but not everything makes sense. What is your assessment? I would be grateful for positive and negative comments.

Attachment: (Black: current; Red: conversion)


Best regards
Obsthaendler

Addendum: The small red rectangle to the left of the balcony (X) would be the roof terrace extension on the top floor. I sketched that a bit confusingly.

Have you already inquired at the building authority? The garage is located on the property boundary? You now want to create living space there, which is usually rejected in our community. That would mean all your plans are then off.

The idea even came from the building authority because the roof extension was rejected. Yes, the garage is on the property boundary.

Do you want to get from the garage to the upper floor? If not, there would be the possibility to build an outdoor staircase over the garage roof (the small red box in front of the house would then be a bit smaller). This would give you a small forecourt on the garage roof in front of your upper floor.

Well, the idea of coming directly from the garage into the apartment/house is really nice and above all practical. I made another 3D view and edited it a bit with Paint. The situation is really difficult to explain.

The red area would be the 9x5m extension. The green area would be the apartment/house. Yellow are the individual floors. Behind the house is the garden and the south side.

Here is another view from the south side, as I could imagine it with the roof terrace. On the right you can see the extension again