ᐅ Site Planning for New Single-Family Home Construction, 180 sqm, with Space for a Grand Piano

Hello everyone,

I have mostly been a silent reader until now, but I’m stuck with my plans and need some advice. Here are the basic details first:

Plot size	900 sqm (already owned)
Slope	Entire plot drops from north to south by about 1.2 m (4 ft) over 29 m (95 ft), within the building envelope of the house over 13 m (43 ft) it drops about 0.6–0.8 m (2–2.5 ft)
Site coverage ratio	0.2
Floor area ratio	0.33
Building envelope, building line, and boundary	House 15x11 m (49x36 ft), garage 6x8.5 m (20x28 ft); garage width can increase if it remains within the building envelope of the house. The building envelope was defined for a smaller plot, which was later extended eastwards (see image Baufenster.jpg). I assume the envelope may be moved east accordingly, but approval is still pending.
Edge development	Garage only
Number of parking spaces	2
Number of storeys	2 full floors
Roof type	Gable roof with 25–30° pitch
Orientation	View from living-dining area towards northwest, as this side is unobstructed

Maximum heights / restrictions	- Wall height 6.1 m (20 ft) (measured from top of ground floor slab) - Base height 0.3 m (1 ft) (from top of ground floor slab) - Excavations not allowed - Filling up to 0.5 m (1.6 ft) allowed - Width-to-length ratio must not significantly deviate from 1:1.2 - Excavations and fillings allowed for garage access (base height up to 1 m (3.3 ft))
Basement, floors
Number of occupants, age	Currently 2 adults + 1 child (space for a second child must be possible)
Space requirements on ground floor	Large entrance area with lots of storage, generous living-dining room with pantry, guest room, guest bathroom
Space requirements on upper floor	Bedroom with optional separate walk-in closet, bathroom, child’s bedroom 1, home office. (If there is a basement, the guest room will move there to make space for a second child’s room upstairs. Without a basement, a second child’s room is needed on the upper floor.)
Office	Required (1 home office)
Occasional overnight guests per year	Occasionally for 1–2 days, about 5–10 people.
Open or closed design	Mixed. Staircase outside the living area, but an atrium in the entrance area would be nice. Open living-dining area is good for spaciousness, but it would be advantageous if it can optionally be separated.
Open kitchen, kitchen island	Open kitchen yes, kitchen island not required. We prefer a U-shaped kitchen for short distances.
Number of dining seats	6+2 (dining table size 2.2x1 m (7.2x3.3 ft))
Music/sound system wall, TV wall	Should be on one wall and provide storage space. We didn’t like a design where the TV acts as a room divider between living and dining.
Balcony, roof terrace	If there is space in the bathroom for a sauna, a balcony would be nice. Probably omitted for cost reasons.
Garage, carport	For 2 cars. Garage obviously preferred but not essential. Possibly a combination where the carport also covers the main entrance.
Special considerations	View towards southeast is not pleasant due to industrial sites.

Homeowner requirements
Bright with lots of space, modern, open but not too stylish. Function follows design.
Lots of space and storage, no dark hallways, entrance area ideally with an atrium.
Guest bathroom and staircase to upper floor should not be directly at the main door (to avoid dirt area).
We have a grand piano (1.6x1.8 m (5.2x6 ft)), which must be accommodated in the house (an heirloom with personality, occasionally played). Ideally in the living room on the ground floor in a dark corner to avoid direct sunlight. Alternatively upstairs, but definitely not in the basement.
Well insulated. We are considering QNG certification to qualify for the KfW loan, but not if it leads to unreasonable extra effort.

House design
Planned by: Do-it-Yourself

What do you especially like?
The version with a straight staircase is basically just a larger version of the sample house with a 10x12 m (33x39 ft) footprint. I’m not a fan of straight stairs, and the basement access would go through the living room. However, the entrance with a separate wardrobe is appealing.

With the bay window variant: the bay window likely increases costs. The guest bathroom is accessed through the dirt zone near the entrance door. If I swap staircase and guest bath, the bathroom won’t have a window unless I move the garage forward as well.

With the 10x12.5 m (33x41 ft) variant: The grand piano somehow doesn’t fit well.

Personal budget limit for house, basement, including fittings, garage, terrace, driveway
900,000

Preferred heating system:
Air-source heat pump with underfloor heating and ideally also central residential ventilation.

If you have to give up on certain features or expansions, which ones would you drop?
The grand piano can be moved upstairs if necessary. The garage can be replaced by a carport.

Which features can you absolutely not do without?
The basement is still under discussion. My wife prefers having a basement. I could live without one.

Why is the design like it is now?
Experimenting with SweetHome 3D after studying many show homes and floor plans, none of which suited us because a room was always missing or there wasn’t enough space for the grand piano in the living area.
The goal is to get a rough idea of how much living area is needed to fit all the desired rooms, so we can then estimate costs.

I try to keep the footprint to 10x12 m (33x39 ft) so that the overall living area doesn’t get out of hand. However, this limits fitting a guest room as well as the grand piano on the ground floor. The space shouldn’t feel cramped. I definitely do not want to make it bigger since we don’t need extra space upstairs.

I’m open to all criticism. My thinking is probably stuck on these floor plans, so a push in a completely different direction might be helpful.

Questions I am asking myself:

• Is a budget of 900,000 enough to cover house + basement + garage + driveway + terrace and garden fence?
• Is a basement significantly more expensive? If I need a utility room, storage, and a second child’s bedroom instead of a basement, that’s also quite costly.
• Does it make sense to put the guest room in the basement? We hope to get some daylight in a southeast-facing basement room, as this is the lowest part of the plot and excavation will be necessary for garage access anyway.
• Can I fit all my requirements into a 10x12 m (33x39 ft) footprint without the grand piano feeling too cramped?
• Is a standard house (or free planning with a general contractor) enough for our needs, or should we definitely consult an independent architect beforehand?
• Is the house orientation reasonable or are there better options? We are quite restricted by the building envelope but other houses in the development deviate considerably. We intend to request moving the house eastwards since the plot has been expanded there.
• Does it make sense to put the garage basement instead of the house? We don’t need a large basement, but 50 sqm (540 sq ft) would be good.