ᐅ Expanding a Two-Family House into a Three-Family Home – Looking for Ideas

Hello everyone,
we are facing the following “problem”:
We have an old house (foundation 9 x 10 meters (30 x 33 feet)). On the ground floor lives my mother (65 years old), on the first floor my grandmother (almost 90 years). The attic is currently used as an office. There is one main entrance with a shared staircase. The house has an unfinished basement. It was built in 1951.

We are a family of four and are looking for ideas on how to renovate/extend the house so that we can all live in it together. So far, we don’t have any perfect solution or clear ideas. For the roof, we would prefer a single-pitched roof. Maybe an extension in the form of a cube or a terraced house on three levels with (roof) terraces, or an additional floor (although we prefer not to increase the height of the house too much). We would rather extend the house in length and width than in height.

For our apartment, we imagine a large kitchen-living area, an open living room, a small guest bathroom (not mandatory), two children’s bedrooms, a bathroom with shower and bathtub, a bedroom, and possibly a storage room. Lots of glazing/window fronts. Ideally, our apartment would have its own separate entrance.

The great-grandmother’s apartment could be rented out at some point.

We would like to renovate and rebuild the house as energy-efficiently as possible (passive house standard, if possible). The plot is about 800 square meters (8,600 square feet).

Has anyone done a similar project or have ideas for the planning?
We appreciate every tip or suggestion!
Thank you 🙂

Baubiene321 schrieb:

We appreciate any tips or suggestions!

Existing building plans? Zoning plan / building permit? Are three-family houses even allowed? Desired living area? Budget? Passive house standard as default = this will be more expensive than demolition and new construction (with an existing building of 9 x 10 m (30 x 33 ft) plus your extension, costs can reach seven figures).

Budget max. 700,000€.
There is no building plan / zoning plan.
Desired living area approximately 130 sqm (1,400 sq ft).
A three-family house is possible (since a neighbor recently converted a property into three apartments).

...Extend the building and bring the rest up to Passive House standard?
Demolish the shed, build a new structure on the site, probably saving a seven-figure amount...

Ok, it’s just difficult with great-grandma… a challenging situation

Baubiene321 schrieb:

Budget max. 700,000 euros
There is no local zoning plan.
Desired living area about 130 sqm (1,400 sq ft)
A three-family house is possible (since the neighbor recently converted to three apartments as well)

Then you should consult an architect and an energy consultant. An extension will cost around half a million euros plus the architect’s fees. However, this will only achieve a standard energy efficiency level. You can use the remaining budget for renovations. But a refurbishment to passive house standard is absolutely out of the question.