ᐅ Development plan in North Rhine-Westphalia – Is an attic conversion possible?

Hello everyone,

I have a question regarding our development plan in NRW.

The requirements specify a one or one-and-a-half-story building style with an eave height of 4.50 m (15 feet) and a maximum building height of 9.50 m (31 feet).
From what I have researched so far, this means that on the upper floor (first floor) we can have at most two-thirds of the area of the ground floor.

My question is about the desired attic floor. Is it allowed under this development plan to have both a first floor and an attic floor?

I would interpret the regulation so that the combined area of the attic floor plus the first floor must not exceed two-thirds of the ground floor area, correct?
Can someone confirm this?

If this is the case, is there any reason why a balcony or roof terrace accessed from the attic floor could not be built on a bay window on the first floor?

I hope the question is not too specific...

Thank you in advance.

Best regards,
Matze

A 1-story building design, as I understand it, includes a ground floor and an attic or loft. In my opinion, there cannot be an additional floor between them.

Neither statement is correct or clearly expressed. Sorry.

A single-story building refers to a full floor. As long as the basement is not constructed as a full floor, it is permitted. As long as the additional floors above the ground floor are not full floors, they are allowed. Half floors do not exist.

Matze999 schrieb:
As far as I have researched so far, this means that we are allowed a maximum of two-thirds of the ground floor area on the upper floor.

You are allowed to build over the entire area. The two-thirds rule (assuming it applies, based on what you researched for NW) relates to the habitable height of 2.30 m (or 2.20 m), depending on the federal state. This height results from the knee wall and roof pitch. With a single-family house height of 9.50 m and a knee wall of 1.50 m (4 feet 11 inches), the attic will hardly have any significant habitable height.

Matze999 schrieb:
Is a house allowed to have an upper floor plus an attic according to this development plan?

Yes...
If you don’t have an architect yet, you should read up on the basics… just a tip.
Could it be that you’re not the only one building there? I have independently read these values here a couple of times recently.
@11ant?

Matze999 schrieb:
If that’s the case, is there any reason against building a balcony or roof terrace on a bay window on the upper floor, accessible from the attic?

Bay windows are small architectural features that become even more expensive when adding roof terraces. In my opinion, balconies are primarily intended for apartments within a building, while if you have garden access, you don’t really "need" them as much. Additionally, a roof terrace also adds usable living space, and you need to be able to access it—which usually requires raising the roof by more than 2.30 m (7.5 ft) in height...

ypg schrieb:
I recently read these values here twice independently.
@11ant?

Honestly, nothing about that rings a bell for me. The values aren’t particularly unusual anyway.

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https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/

Hello everyone,

First of all, thank you for the responses. Let's set aside the roof terrace for now. My main question is whether a converted attic is allowed if it provides living space.

ypg schrieb:
As long as the upper floors above the ground floor are not full stories, they are permitted. Half stories do not exist.

From this, I understand that a converted attic is indeed allowed in single-storey construction, correct?

I would interpret it this way: the living area of both the attic and the upper floor must not exceed two-thirds of the living area of the ground floor, right?

Best regards

Matze

Matze999 schrieb:
From this, I understand that a finished attic space is indeed allowed in single-story construction, right?

Yes, as long as all floors above the ground floor have sloped roof surfaces and do not exceed 2.30m (7.5 ft) in height over more than 75% of their floor area.

Matze999 schrieb:
I would interpret this to mean that the living area of both the attic and the upper floor must not be larger than two-thirds of the ground floor living area, correct?

Where did you get the two-thirds from? The regulation refers to 3/4 of the respective floor’s footprint.

This is also a single-story house in NRW.
The zoning plan can, of course, include many other requirements that may prohibit this, such as eave and ridge heights, floor area ratio, and roof pitch.