Floor plan ideas for a detached single-family house as an extension with 3 children's rooms and an office

I still understand that. You want to turn a single-family house into a semi-detached house. Or rather, it already is a semi-detached house. Regarding that, the first thing I would check (have checked) is whether that is feasible on the property. Second residential unit, house number, possibly division of the land, floor area ratio fitting etc. That’s what the building authority is for. Homebuilder companies don’t check such things initially; they first calculate a flat house price, and only much too late do they put their hands in the fire.

I am already in contact with those. Floor area ratio = 0.6, with access, etc. it is 0.8. A sketch from a developer with an extension of 8.5 x 8.5 would also be fine.

I actually thought you needed the rooms. So why _renting_ then?

The apartment has been rented out for years. The space is only now getting tight with the children.

In the old building or the new house?
And how is that supposed to work in everyday life? Kids sleep in the new building, you in the old building? And then constantly go back and forth between two entrances and houses?

No one commutes anywhere. It is supposed to be an independent house with an independent entrance, which due to avoiding setback distances should only be attached.

Do you mean the age of the basement? – I estimate the house itself, as said above, to be younger, and your sketched overall building would have a building depth of 22 meters (!)

Attached is a sketch of the object. I hope that makes it clearer (?).
Black is the semi-detached house from 1939, red the extensions from 1981 (balcony, "living room" and double garage).
Regarding the depth, you are right. But I find nothing contrary in the building plan and the planning office also did not complain about it.

Do you want to move the cellar of the old building? Tear down the old building? Or how do you want to use the existing cellar? There’s a house standing on it!

No moving. Concrete slab next to it and the new house on that. If I have to put anything in the cellar, I use the existing building. It’s basically my house. I am also the only one using the “living room cellar.” There is also an entrance from the garden for that (marked on the above plan, right next to the extension).

Not much will be left of it then. The little girls get the balcony.

Unfortunately, that’s true. The 3 meters to the property boundary. Roof terrace on the balcony would be an option. I unfortunately have to face some kind of compromise.

Why don’t you terminate the tenants and put the kids in the attic and do an interior renovation for yourselves with that money?

There are several reasons:
- The whole thing is hard to imagine without a long construction site and dust in the house (my wife is ultra scared of asbestos “and all that toxic stuff” and doesn’t want anything to be “stirred up.” I know the problem isn’t that big. But you know, women…
We want to avoid the long construction site in the house. We live and work inside.

- The tenant would be gone and would not refinance anything
- The “funding” (or loans) is better for new buildings and there are more options. For example, new technology will be installed, new photovoltaic on the roof, heat pump, air exchange.
- I could eventually completely tear down the old house and put up something new. With a renovation I can only partially modernize. It still remains an old building.
With the new building I would have “peace” for a while.
- We need a separate entrance. The problem with my wife and own mother “is somewhat more severe with me.” The stairwell should be separated for us and my mother with her partner (ground floor) as well as the tenants (upper floor).

Do you mean the age of the cellar? – I estimate the house itself, as said above, to be younger, and your sketched overall building would have a building depth of 22 meters (!)

See above.

I am open if I’m wrong. That’s why I am here in the forum. But those are the reasons for now.

I agree with the previous speakers. Before you wildly plan any crazy ideas, first use the existing space optimally. How large is the rented area? Can the tenant be terminated or is it family or similar?

The area is 64 sqm. The toilet is in a separate small little room. The attic above is even converted. The remodeling idea itself would be nice. If the costs weren’t so high that I could almost build a new house and it wouldn’t be an “eternal” construction site.
It makes a difference whether I refinance amount x with the tenant and can live dust-free in the new house or whether I have to spend amount y, finance it completely alone and then have a long construction site with noise and dust in the house.

As said, just our understanding. Please correct me and put me on the path of enlightenment. :) That’s why I am here.

Danwood delivers decent quality for standard solutions, and is hard to beat when it comes to price/performance for fully turnkey solutions without luxury demands. But with you, a standard solution will certainly not be possible (fire protection etc.), so I don’t think Danwood should necessarily be contact number 1.

You are completely right. A standard solution can’t work alone because of the party wall. That side is practically dark and I then need light through other windows or openings.
We have already had appointments with prefabricated house providers (Schwörerhaus, Allkauf Haus, Hanse Haus) and on Friday again two (Bien-Zenker, Fingerhut Haus). I have also had phone contact with others. A developer has also been here. They are always familiar with the problem. There are no concrete offers yet.
According to the manufacturers, they can get there with a crane. The street on the north side is a large main road and would have to be partially closed for that.

What does the development plan say about the building envelope? I really can’t imagine such a huge building envelope. Isn’t the floor area ratio already exhausted?

According to the planning office, it fits. I just must not build more, otherwise it becomes critical. 8.5 x 8.5 should be okay.
The bigger problem is probably the parking spaces. If I somehow get 6 on the existing site overall, that’s okay.
But that will probably be difficult.

I hope the whole thing is now clearer?

The pure subsidies for old buildings, especially if you can plan everything as energy-efficient renovation & age-appropriate remodeling (possibly also implemented in sections), are actually much, much better than for new buildings.

And even in old buildings, a lot can be achieved - including photovoltaic (if the roof shape even allows it), heat pump, etc.

According to the planning office, it fits. I just shouldn't build any more, because then it becomes critical. 8.5 x 8.5 should be ok. The bigger problem is probably the parking spaces. If I can somehow get 6 in total on the existing site, it's ok. But that will probably be difficult.

The statement from the office is worthless. Your building application should prove that the floor area ratio is complied with. Also the compliance with the number of parking spaces.

Parking spaces can already be planned.

It is supposed to be a separate house with a separate entrance, which should only be attached in order to avoid setback areas.

That was not clear: You only mentioned 3 children's rooms, kitchen and 2 bathrooms, and an office, but not living and bedrooms (hence the inquiry and misunderstanding).
You do not even want to plan a technical room... so the new house will not function independently.

Rental and thus refinancing of the house possible

What did you mean by that?

The problem is obvious and lies in your planning, that you are mixing many things. While an extension belongs to a residential unit, you want to attach an independent house. If you take independence seriously, you would probably have to divide the plot, possibly ideationally divide it. Storage space belongs to a house as well as technical installations. Connections are laid to the house. Of course, you can still privately use the old cellar of your old house, but economically that creates a dependency. Simply using technical equipment from the old building and later tearing down the old building is not possible. A new building must comply with the new Renewable Energy Act requirements. A house should also function for a later separation (sale, rental... whether old or new).

I assume that the 8.5 x 8.5 results from the calculation of the floor area ratio or plot ratio?
At 8.5 x 8.5 you have about 55-60 sqm of living space per floor. Have you calculated what room areas come out if you assume you do not want to build a 3-story tower? It's not like you need 50 sqm of all-purpose room. But 4 bedrooms each 12 sqm, small bathtub and small shower bathroom together 12 sqm, technical room of 8 sqm, storage room of 2 sqm, office of 8 sqm and hallways including stairs of 20 sqm, I am at 22 sqm for the rest (kitchen, dining and living room)...

In addition, the plot is being abused so much that you can hardly find a garden anymore. Where would the added value be then?

The area is 64 sqm. The toilet is in a separate small little room. The attic above is even developed. The remodeling idea itself would be nice. If the costs were not so high, so that I could almost build a new house, and also not be an "eternal" construction site.

That sounds ideal: area-wise ideal for 3 children's rooms. It is the most comprehensible, ecological, and with the subsidies the most economical, and ultimately the most obvious to have the rooms upstairs developed for the children, even for half a year moving out into a holiday apartment and making everything fancy during that time.
I would not want to live in such confined space even with two people, and a garden by definition is more than a 3-meter strip.
You currently, I think, have too many disadvantages because of the old property and are fixated on the idea of a new building. The consequences should be foreseeable.
Therefore, I advise against ruining a beautiful residential plot.

But you know, women...

No, what do you mean?

Here with an extension. 3 m distance to the boundary.



and upper floor



that is 100 m2 living space.