Development plan and the resulting house plan

Hello everyone,

we are planning to build a new house and now have some questions about the development plan.
Maybe you can give some concrete answers or estimates about the situation here.

On Friday, I will probably go to the municipality again and try to clarify things more concretely.

Briefly about the background or framework conditions:
We own the parcel number 2414 and the adjacent plot at the back, which is outlined in purple and marked with a circle for better identification.
The plot area is about 750 sqm.

We currently live in the front house on parcel number 2414 and use the back plot as a large garden.
The street adjacent to the north is not yet built. It is planned for 2020.
Since the current house is an old building from the 70s with two apartments, we would like to build a new one at the back. Currently, we live with 2 children in only 95 sqm. Since my wife, as a self-employed person, has an office and the kids only have a shared children's room, it is all quite tight.

The street has been planned for many years, but now the city has acquired the last plot to implement it. According to the municipality, it should now be built next year.

So we took a closer look at the development plan. Unfortunately, I am not very happy about it.
I’ll try to structure the individual points and questions a bit.
Let's see how far we get with this thread.
Attached is the relevant excerpt of the plan.

1. It is a mixed-use area.
2. The number of full floors is set at 1 (mandatory). This means for me, first of all, that I may only build one full floor and then the attic may have a ceiling height of 2.2m or more on max. 2/3 of the area.
3. Roof pitch is specified in the development plan statute as 22 - 28°.
4. The great sentence in the statute: "The height of knee walls, measured from the top edge of the ceiling to the intersection of the outer edge of the masonry with the top edge of the purlin, may not exceed 0.5m."
So there's no big leeway here either. Thus, the usable attic will be significantly smaller than the ground floor.
5. Site coverage ratio = 0.25; I see this as uncritical for our project
6. Floor area ratio = 0.3; I see this as uncritical for our project
7. According to the statute: "Dormer windows are only permitted in main buildings with flat-lying windows." This means for me, dormers are not allowed and only roof windows are possible, right?

We once considered building a house with ground floor + upper floor. Also with some knee walls on the upper floor, but 0.5 m is really quite extreme. Thus, a lot of space will be lost on the upper floor and I have to make the ground floor larger.

The plan is a house of about 130 sqm for a family of four including an office.

We currently have the following 3 ideas (all still very rough)
1. Ground floor + upper floor with reduced area. So the ground floor a bit larger and the upper floor with knee walls. Ground floor maybe about 75 sqm, upper floor about 60 sqm. Roof pitch as steep as possible with 28°.
2. Alternatively, basement + ground floor each with about 75 sqm and possibly a "cold" attic and gable roof with 22°. But then living rooms (children's room/office) would have to be in the basement. So a basement is needed that must also be well insulated and have large basement windows.
3. Or a bungalow with about 125 sqm. Advantage: living space is somewhat smaller overall as no stairs are needed and one bathroom suffices. No intermediate floor. Space under the roof can be used as storage. Disadvantage: large slab, large roof. More plot area is lost.

How would you rate the three options in terms of cost?
We want to build as cost-effectively as possible, without much frills.
Possibly relevant info: it shall be a KFW40 house. It shall have either controlled residential ventilation or a decentralized ventilation system.
Own work for sure: plastering, flooring, electrical work.

What other suggestions do you have? Advantages, disadvantages?

It was also considered to build a multi-family house with 3 or 5 units. But after looking at the development plan, that is definitely off the table...

I think there will be more threads about our planning as it gets more detailed. This is just a first starting point.

Thanks in advance for your help.

Best regards
Specki

a ceiling height of 2.2m

Where do the 2.2m come from?

1st floor + upper floor with reduced area.

My favorite, if it weren’t for the meager 28° roof pitch.

2. Alternatively basement + 1st floor

Only if there is at least 1m difference in terrain height on the building plot.

3. Or a bungalow

Plot and floor area ratio are large enough (from when is the development plan?). Considering the limited roof pitch my preferred solution.

Disadvantage: ..., large roof.

With south orientation and photovoltaics rather an advantage.

Where does the 2.2m come from?

I got the definition from the internet: "What is understood by a full storey? “A full storey is an above-ground storey that has a clear height of 2.20 m or more over at least half of its floor area. A top storey is only considered a full storey if it has the clear height mentioned in sentence 1 over more than two-thirds of the floor area of the storey below.”

My favorite, if it weren’t for the meager 28° roof pitch.

Yep, I kind of think so too.

Only if there is at least 1m terrain height difference in the building plot.

That’s not the case. Absolutely flat.

Plot and floor area ratio are large enough (from when is the development plan anyway?). Given the limited roof pitch, my preferred solution.

Yep, the bungalow would be no problem. The development plan is from 2001 and still valid according to the city.

With a south orientation and photovoltaics rather an advantage.

Sure, you can put a nice big photovoltaic system on it. I’m currently installing a 24.5 kWp system on my current house. But roof area costs more than the photovoltaic modules could make up for, I would say. So it’s not necessarily an advantage, but due to the photovoltaics it’s not quite such a big disadvantage.

Thanks for your answers!

I just don’t understand the severe restrictions in the development plan. I totally understand that you can’t just put a huge block there now. But I find the plan really limits you quite a bit.

Best regards Specki

I would build a shed roof house on it, if allowed. Expand the top so that the children's rooms are there and only theoretically "half a floor." If the remaining rooms are on the ground floor, then the KS will suffice. By the way, I find 130sqm including the office a bit too little if built without a basement.

Only gable roofs with a 22° to 28° roof pitch are permitted according to the statutes.

Yes, most people probably see that as too little. It's enough for us.

Only gable roofs with a pitch of 22° to 28° are permitted according to the statutes.

Ok. Then the bungalow and in the roof the storage room including the technology.