Large single-family house with 4 children's rooms - convertible into 2 residential units

Hello everyone,

we are planning a larger house for prospectively four children with the option that grandparents could move in later. Since the space requirement will not be permanently that high, the house should be dividable into two residential units – e.g. for subletting, for an adult child with family (as we ourselves grew up) or for flexible use and/or better resale value. My parents live on the northern neighboring plot; we try to take this into account (they want to continue living there but are still fit).

I look forward to honestly justified criticism – the more detailed, the better.

Plot and framework conditions

[*]Location: infill development, no development plan → oriented to inhomogeneous surrounding buildings
[*]Plot: approx. 740 m², slightly elevated (approx. 1 m) compared to the street, then level
[*]Site occupancy index: 0.4
[*]Floor area ratio: not specified, 2 full floors are common locally
[*]Distances: 3 m to neighbors, up to 6 m at property boundary possible
[*]Edge development: only carports allowed
[*]Parking spaces: 2 required (driveway counts as second space)
[*]Roof shape: gable roof 23°, permitted 20–45°
[*]Neighboring houses: height 7.8–9.2 m → planned building 8.81 m
[*]Orientation: street in the east, entrance planned in the north

Requirements of the builders

[*]Style: efficient cuboid with gable roof, flexible in appearance
[*]Basement: no (too many rooms that do not fit in the basement)
[*]Floors: 2 + attic as storage
[*]Residents: currently 2 adults, 2 children → long-term 4 children + possibly grandparents
[*]Space requirement: 4 children's rooms, 1 study (home office), 1 guest/grandparents' room, kitchen, living area, utility room, sufficient storage
[*]Kitchen: open with cooking island, 6–8 dining seats
[*]Fireplace: no
[*]Balcony/Terrace: no upper terrace, focus on garden
[*]Garage/Carport: carport
[*]Kitchen garden: available but not prioritized
[*]Area: preferably under 200 m² living area (tax advantages, lower ancillary costs)
[*]Goal: place the house as far south as possible so that the parents’ house still gets sun in the south

Design status

[*]Planning: by a freelance planner at a fixed price → intended as a basis for offers from homebuilding companies
[*]Current status: largely final, last optimization round planned

What we like

[*]Room program meets all requirements
[*]Utility room directly next to the bathroom (laundry without stairs)
[*]Large, bright kitchen-living area with plenty of storage
[*]Attic compensates for the missing basement
[*]Good size of the children’s rooms
[*]Overall efficient floor plan

What is not yet ideal

[*]Hallway width (1.25 m) rather narrow
[*]Minor compromises in furnishing, but overall satisfied

Financial aspects

[*]Planner’s estimate: 550–600 k€ (outdated)
[*]Own expectation: approx. 650 k€
[*]Upper limit: 700–750 k€
[*]Heating technology: heat pump with underfloor heating

Priorities

[*]Indispensable: 4 children’s rooms
[*]Dispensable: some area or number of windows, if necessary

Design development
We planned for a long time ourselves and then hired a planner. Optimization was done back and forth in a ping-pong process.

Furnishing
A large couch and a TV in the shelf still belong in the living room. The large wardrobes in the rooms will probably not be that long and in the end, e.g., the desk will be there. The bed will probably also not be in the study. The kitchen island includes stove and sink with a workspace in between and storage areas at the edges.

Special features
If you remove the wall between the two western children’s rooms, a fully-fledged 4-room apartment is created upstairs (kitchen-living room + three rooms + 2 bathrooms). The separation then takes place, e.g., along the red lines. This significantly increases flexibility – e.g. for tenants, renting or later adult children. Even in the worst case (sale), the floor plan remains value-stable and versatile. Overall, the house feels to us like a very efficient implementation of a large room program – but we are open to any well-founded criticism or suggestions for improvement.

Specific questions:

[*]Floor-to-ceiling window in the bedroom or not (possibly desk space)?
[*]Is the small window in the upper hallway sufficient?
[*]Is an additional south-facing window for the children’s rooms in the south useful?
[*]The house stands quite far on the southern boundary – is this understandable from your point of view (because of parents’ house in the south)?
[*]Utility room directly next to the bathroom with prepared washing machine connection for possible separation of residential units – practicable like this?
[*]Should the wall between living room and kitchen be designed as non-load-bearing as an option? Probably costs about 5 k€ more.

We look forward to comments on:

[*]Room layout
[*]Lighting / orientation
[*]Proportions / furnishability / everyday suitability
[*]Rentability and value development
[*]Anything else you can think of

Thanks for thinking along!

In the floor plan game, others are definitely more involved. Basically, I like the flexible idea. Of course, there is the risk that not all details are achieved 100% but there are compromises. However, the following caught my eye when skimming through: - leave out the ring anchors on the ground floor and install the windows including shutter boxes on the existing concrete ceiling - you can do the same in the attic if you also make the upper ceiling a concrete ceiling - with a little more steel it should be possible to make the walls between the kitchen and living room non-load-bearing. It actually can't cost 5k - skip the roof window and plan the photovoltaic system fully. Light through the two gable windows is enough - I would design the front part of the attic as a playroom and use the back area as storage space - in the guest WC I would take a shower instead of a bathtub

We planned ourselves for a long time and then hired a planner.

Whoever the planner is, they are not worth their money. Best to quickly throw the botch in the bin.

I do not see the first part of the planning. Where is the house supposed to stand on the property?

You want to build a house for 4 children, which might later be divided into 2 residential units, and plan 2 parking spaces, one of which is also trapped? Just a little joke, right?

In my opinion, the photovoltaics are not well planned. Assuming the DF have a N/S orientation, then fully cover the roof on the south side. In my opinion, 33 modules fit there. The north only if you have money to spare. From October to March, there is zero yield there. But the WP needs that then. In my opinion, the roof pitch should also be a bit steeper, 30 degrees.