ᐅ Single-family house approximately 160 sqm with flat roof – Optimization / Planning

Good morning,

the plot has finally been purchased... now the actual planning begins. Attached is our first draft, which I would like to open for discussion here. It is still very basic at this stage; no windows or furniture are drawn in yet, that will follow in the next step.

Development Plan / Restrictions

Plot size: approx. 500 sqm (5,380 sq ft)
Slope: no
Site coverage ratio
Floor area ratio: 0.4
Building envelope / building line / boundary setback: 3 m (10 ft) distance from plot boundaries
Edge development: yes and no, garage with 1 m (3 ft) side setback, 5 m (16 ft) front setback
Number of parking spaces: 2
Number of stories: 2 full stories
Roof type: -
Architectural style: -
Orientation: -
Maximum heights / limits: ridge height < 6.2 m (20 ft); eaves height < 9.7 m (32 ft)
Further regulations

Client Requirements
Architectural style, roof type, building type: flat roof
Basement, floors: no basement, ground floor, upper floor
Number of occupants, age: 4 (two adults, two children)
Space requirements on ground and upper floors:
Ground floor: open living/dining area with kitchen, pantry, utility room, bathroom with walk-in shower, guest room (later bedroom for older age)
Upper floor: bedroom, 2 children’s rooms, walk-in closet, 1 bathroom with walk-in shower, laundry room
Office: family use or home office? no
Overnight guests per year: yes, about once a month over the weekend
Open or closed architecture: open
Conservative or modern style: modern
Open kitchen, kitchen island: open kitchen with freestanding island
Dining seats: 6-8 persons
Fireplace: no
Music / stereo wall: yes, integrated with the TV
Balcony, roof terrace: no
Garage, carport: yes, preferably a double garage with storage / hobby room due to no basement
Kitchen garden, greenhouse: no (possibly raised beds)
Other wishes / special features / daily routine, including reasons for design choices or exclusions:

• Straight staircase (even though it takes up more space)
• From the kitchen, the dining area and living room should be visible

House Design
Who designed the plan: Do-It-Yourself
What do you particularly like? Why?

• Straight staircase
• Open kitchen/dining/living area

What do you dislike? Why?
Price estimate by architect/planner: -
Personal price limit for the house (including fittings): 350-400 thousand EUR
Preferred heating system: air-to-water heat pump (underfloor heating)

If you had to give up something, on which details / expansions
- could you do without:
- could you not do without:

Why was the design made this way?
No architect involved yet, own planning inspired by online sources, magazines, and model/holiday homes

What do you think makes it particularly good or bad?

What is the most important / fundamental question about the floor plan in 130 characters or less?

Thank you very much for your suggestions, criticism, etc.!