New energy-efficient detached house with a granny flat

Hello everyone,

We are currently considering building a new single-family house (ideally a passive house, depending on costs) with a granny flat with a separate entrance (for grandma). An alternative would be to renovate/reconstruct the current house from the 1950s, but the effort would probably be much higher and the costs not significantly lower (this is our estimate). Therefore, we are currently researching an energy-efficient new build with a granny flat. The house should be about 200 sqm (of which the granny flat is about 65 sqm), possibly smaller depending on the floor plan. I wanted to ask if anyone has experience with new builds with a granny flat and can possibly give us tips on floor plan design. Maybe someone can also tell us the approximate costs (just for comparison) and what else needs to be considered? Exactly, the house should have no basement and will be built in Regensburg. Thank you in advance for your help!

Should the old house be demolished and then rebuilt?

The question is hard to answer, roughly like "how much does a car cost." An electric car would be good.

Demolition costs take your time and compare.

Find a company that specializes in passive houses. It will be cheaper than a company that builds according to the energy saving ordinance and well, if necessary, a passive house is also possible.

Assume 2,500 to 3,000 euros per sqm + additional construction costs + demolition.

Floor plan without consideration of the plot is difficult. Look around here and on the internet. Single-family house with a granny flat is not uncommon. Google zero barrier as a planning aid for the granny flat.

It is important that you create a precise room plan for yourselves. Bedroom bed with the dimensions xyz. Distance wall - bed edge, continuous wardrobe meters etc. Especially what perhaps distinguishes you from others must be included.

The old house is supposed to remain standing because it is currently inhabited anyway. Sooner or later it may be demolished. The new house is to be built next door. Has anyone had experiences with construction companies regarding a granny flat?

Is the old house supposed to be demolished and then rebuilt?

I. But my builder is certainly not going to Regensburg.

Any home construction company will build something like that for you.

Are you still allowed to build a house of that size on the plot?

Everyone builds a [Einliegerwohnung]. There are no restrictions on the choice of builders.