ᐅ Corner house based on a diagonally shaped plot – options and budgetary implications

Hello everyone,

We are currently considering buying a plot of land in southern Lower Saxony and building a house.

I have shown the plot below. The buildable area lies within the points K, O, M, M1 (red lines). The required setback distances to the neighboring properties (3m (10 feet)) have already been taken into account.

Cardinal directions: South is on the left, West at the top, North on the right, and East at the bottom.
The road runs along the property boundary D-A.

Due to the diagonally running buildable area on the left, a “standard house” seems difficult to layout, and we are leaning toward an L-shape, as we don’t want to build too “deep” into the garden. Toward the back (west), the plot slopes downward somewhat. That means that the area to be built on might need to be filled (or a basement could be added). Toward the garden at the back, a step or level difference could be used, for example.

Basic idea (where W-V-Z-A represents a garage with an attached shed):

Gross floor area: 6 x 10m (6 x 33 feet) + 7 x 7m (7 x 23 feet) = 109 sqm (1,173 sq ft)
Upper floor according to the development plan as an attic (no two full stories allowed) with up to 75% of the ground floor area, i.e. 102 sqm (1,098 sq ft) * 0.75 = 81.75 sqm (880 sq ft)

Total: 190.75 sqm (2,053 sq ft) – I would expect about 15% “loss” from the total area to the living area, so around 162 sqm (1,744 sq ft) of living space.

- The house does not border the edge of the buildable area on the right side, so the garage can be a bit wider (4m (13 feet)).
- The house is planned as a solid construction, probably with an architect because of the L-shape, as I couldn’t find such floor plans in the catalogs of solid house providers (e.g., Viebrockhaus).
- We are currently leaning toward KfW55 standard, as we want to avoid a ventilation system (sensitive to drafts).
- A basement would be nice but seems too expensive at first glance.
- A photovoltaic system must be included in the planning (system size is still flexible).

Do you think a project like this could be realized within a budget of €550,000 (excluding the land), especially considering the L-shape and the accordingly more complex roof shape (gable or hip roof is required)?

Often, price per square meter figures of €3,000 - €3,500 are mentioned here, which might be just within our budget (€486,000 - €567,000).

However, I am unsure a) which components of the construction are included in those prices (architect, incidental building costs, earthworks, connection of utilities from the street, etc.) and b) to what extent the L-shape and the related complexities increase this figure. Since we do not live in the immediate vicinity, we cannot supervise the construction every day, so we would either a) appoint the architect as the construction manager (for individual contracts) or b) hire an independent expert to oversee the construction if a general contractor is responsible for execution.

Potential DIY contributions:
Painting / wallpapering / possibly door frames
Through our close family circle, we have access to farming equipment such as tractors and trailers (which might be useful for earthworks, for example)
We also have a tiler in the close family circle who has helped on other family construction sites and who we might involve for the sanitary areas

I would appreciate your opinions and experiences. I am happy to provide further information if needed.

Thank you and best regards,
Bob