ᐅ Semi-detached house within a building plot measuring 8.5 m by 15 m (width x depth)
Created on: 20 May 2025 19:02
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GregorBerger
Dear housebuilding forum,
After several years of searching, we have finally purchased a plot of land (with an existing building to be demolished) in our desired location. This also marks the end of my many years of purely passive participation in this forum. Since we were primarily looking for renovation projects rather than new builds, we naturally have some initial questions.
The plot, approximately 500 m² (5,400 sq ft), lies within the scope of a development plan that was last updated 20 years ago.
Basic data about the plot and development plan:
The development plan places no restrictions on, among other things:
The plan is to build a semi-detached house with another family. Both families have two children each and require two home offices, resulting in a need for six rooms per semi-detached unit. If we make progress here, I will create another thread in the floor plan forum and fill out the questionnaire.
Since the building envelope width of 8.5 meters (28 ft) is too narrow for semi-detached units side by side, they would have to be arranged one behind the other. Garden access and terraces would then be located on the narrow sides (one facing the street and one facing the main garden at the rear). This type of semi-detached house is quite rare. I have looked around in real life but have not found any examples. Only the Büdenbender semi-detached house Gemello SD 135 roughly corresponds to this layout (though not to the measurements).
I have had some informal discussions with an architect I know (who now only works on office buildings) and the building authority, without encountering any fundamental contradictions so far.
I have already applied the @11ant basement rule, according to which a basement seems obligatory because there is more than 2 meters (7 ft) of height difference within the building envelope. However, I do not understand how this relates to the “base (plinth)” restriction of max. 60 cm (24 in) in the development plan. My layperson assumption would be that one floor (the ground floor? the lowest residential floor? the lowest full floor?) may start a maximum of 60 cm (24 in) above street level.
My first questions for you:
Thank you in advance,
Gregor
After several years of searching, we have finally purchased a plot of land (with an existing building to be demolished) in our desired location. This also marks the end of my many years of purely passive participation in this forum. Since we were primarily looking for renovation projects rather than new builds, we naturally have some initial questions.
The plot, approximately 500 m² (5,400 sq ft), lies within the scope of a development plan that was last updated 20 years ago.
Basic data about the plot and development plan:
- Building is permitted from 3 meters (10 ft) to 18 meters (59 ft) depth (so 15 m (49 ft) for the house)
- After deducting setback areas, a width of 8.5 meters (28 ft) is possible
- Slight slope across the building envelope with a rise of approximately 2.2 meters (7 ft)
- 3 full floors permitted
- Site occupancy index (ground coverage ratio) 0.4
- Floor area ratio 1.2 (cannot be fully utilized due to the aforementioned building envelope)
- Roof pitch 35–45°
- Knee wall (dormer wall) height 60 cm (24 in)
- Base (plinth) max. 60 cm (24 in) above the midpoint along the width of the access area, which is itself 30 cm (12 in) lower than the start of the building envelope
- General residential zone
- Open building style (detached buildings, no shared walls)
- Covered terraces allowed up to 1.5 meters (5 ft) outside the building boundary, provided the site occupancy index is not exceeded
- Roof indentations and structures permitted up to half the eaves length and at least 1 meter (3 ft) from the gable wall
- Fencing with native hedges. Along the street, an additional fence up to 1.2 meters (4 ft) high is permitted.
The development plan places no restrictions on, among other things:
- Building type
- Number of residential units per building
- Height limits
- Basements
- Parking spaces
The plan is to build a semi-detached house with another family. Both families have two children each and require two home offices, resulting in a need for six rooms per semi-detached unit. If we make progress here, I will create another thread in the floor plan forum and fill out the questionnaire.
Since the building envelope width of 8.5 meters (28 ft) is too narrow for semi-detached units side by side, they would have to be arranged one behind the other. Garden access and terraces would then be located on the narrow sides (one facing the street and one facing the main garden at the rear). This type of semi-detached house is quite rare. I have looked around in real life but have not found any examples. Only the Büdenbender semi-detached house Gemello SD 135 roughly corresponds to this layout (though not to the measurements).
I have had some informal discussions with an architect I know (who now only works on office buildings) and the building authority, without encountering any fundamental contradictions so far.
I have already applied the @11ant basement rule, according to which a basement seems obligatory because there is more than 2 meters (7 ft) of height difference within the building envelope. However, I do not understand how this relates to the “base (plinth)” restriction of max. 60 cm (24 in) in the development plan. My layperson assumption would be that one floor (the ground floor? the lowest residential floor? the lowest full floor?) may start a maximum of 60 cm (24 in) above street level.
My first questions for you:
- Are you familiar with similar houses, possibly with names for Googling or similar?
- Would you approach this topic differently?
- What does the rule about the base (plinth) mean?
Thank you in advance,
Gregor
G
GregorBerger21 May 2025 09:44Good morning everyone,
Building on your questions, I’ve taken a closer look and need to correct some details.
The building zone does not start 3 meters (10 feet) from the street but 6 meters (20 feet) from it and then extends 15 meters (50 feet) further inward.
The natural terrain height difference is not 2.2 meters (7 feet), but only 1.8 meters (6 feet), as the re-measurement in the geospatial data portal showed (see attachment).
From the same source, I also created a clearer drawing of the plot with appropriate dimensions (see attachment).
I apparently wasn’t clear enough. On the neighboring house to the left, you can see how it looks. In each building setback area (left and right), there is a garage (one parking space per side) with a driveway in front (one additional parking space per side). That way, you get four parking spaces.
Is that only AFTER the 15 meters? Or also before, meaning within the 6 meters (20 feet) between the street and the house?
So, ground floor? Does that mean that the first full floor has to be at least 60 cm (2 feet) above street level, even if less than 1.4 meters (4.6 feet) of the floor height is visible above the natural terrain along its depth?
Building on your questions, I’ve taken a closer look and need to correct some details.
The building zone does not start 3 meters (10 feet) from the street but 6 meters (20 feet) from it and then extends 15 meters (50 feet) further inward.
The natural terrain height difference is not 2.2 meters (7 feet), but only 1.8 meters (6 feet), as the re-measurement in the geospatial data portal showed (see attachment).
From the same source, I also created a clearer drawing of the plot with appropriate dimensions (see attachment).
ypg schrieb:
You can’t expect two families to block each other’s cars, and that to work. And where are the four parking spaces? You can’t just line up four parking spaces one after another.
I apparently wasn’t clear enough. On the neighboring house to the left, you can see how it looks. In each building setback area (left and right), there is a garage (one parking space per side) with a driveway in front (one additional parking space per side). That way, you get four parking spaces.
ypg schrieb:
After the 15-meter building zone, you are allowed a 1.5-meter built-over terrace.
Is that only AFTER the 15 meters? Or also before, meaning within the 6 meters (20 feet) between the street and the house?
11ant schrieb:
The top edge of the finished ground floor slab.
So, ground floor? Does that mean that the first full floor has to be at least 60 cm (2 feet) above street level, even if less than 1.4 meters (4.6 feet) of the floor height is visible above the natural terrain along its depth?
H
hanghaus202321 May 2025 10:11Thank you for the site plan.
I have added the terrain according to your specifications.
This way, it can work.
Who will get the garden plot? Is it intended to be legally divided with a right of way?
I have drawn it with 2.2 m (7.2 feet) added.
I have added the terrain according to your specifications.
This way, it can work.
Who will get the garden plot? Is it intended to be legally divided with a right of way?
I have drawn it with 2.2 m (7.2 feet) added.
GregorBerger schrieb:
You can see how it looks at the neighbor’s house on the left. In each side setback area (left and right), there is a garage (one parking space per side) with a driveway in front (one additional parking space per side). That results in four parking spaces in total. However, you should also keep in mind that this arrangement blocks direct garden access for larger gardening tasks, which can then only be done through the garage or the house.
hanghaus2023 schrieb:
Who will own the garden plot? Is it meant to be legally divided with an easement?
I drew it with 2.2 m (7 ft 3 in). I think the slope from the street over the first 6 meters (20 ft) should probably not be preserved as a steep incline.
H
hanghaus202321 May 2025 10:58kbt09 schrieb:
I think the slope from the street over the first 6 meters (20 feet) shouldn’t necessarily be maintained as a slope.
The original poster uploaded an elevation plan while I was sketching, showing the first 6 meters (20 feet) as rather flat.kbt09 schrieb:
One must also be aware that this means access to the garden for larger gardening tasks is not free and can only be done through the garage or through the house.Unfortunately, it could no longer be changed ... it will be very difficult anyway due to the sloped terrain.hanghaus2023 schrieb:
The original poster posted an elevation plan while I was sketching; the first 6 m (20 feet) are relatively flat.I know, but that's still about 40 cm (16 inches)... and it’s not yet decided how terraces can be arranged at all in a design like this.Similar topics