ᐅ Single-family home with a basement apartment on a hillside, designed for flexible use

Hello everyone,

I have been mostly a silent reader here for several years and have gained many ideas and suggestions. I have followed many projects here since we started planning our own house build and have benefited greatly, incorporating many considerations into our planning. After purchasing a plot about 2 years ago, our own house construction is now getting closer, with the goal to start next year.

So far, we have worked with 2 different general contractors (GCs), who provided similar concepts but different designs due to the placement of the stairs. We have made some independent changes to the design we preferred.

Due to professional priorities, the project did not have top priority since the beginning of this year. This will change from April, and we will consult several more GCs. Since we have an upcoming appointment with a GC soon, I would like to hear your critical and honest opinions about our concept and design beforehand.

Thank you in advance for your help.


Zoning Plan / Restrictions
Plot size: 600 m² (22 m wide x 27 m deep) (72 ft x 89 ft)
Slope: yes, steep slope (approx. 8 m on the north side and 7 m on the south side; see attached leveling plan)
Site coverage ratio: 0.4
Floor area ratio: 1
Building envelope, building line and boundary: see zoning plan excerpt
Edge development: no, 3 m setback; garage allowed; 5 m setback required from the street side
Number of parking spaces: 2 per housing unit, one of which must be covered
Number of floors: max. 2 full stories + half / stepped floor
Roof type: no restriction
Architectural style: no restriction, except no log houses
Orientation: west
Maximum heights / limits: eaves height max., parapet top max. 4 m (13 ft) on street side; eaves height max., parapet top max. 7 m (23 ft) above ground height on garden side
Other requirements:


Owners’ Requirements
Style, roof form, building type: Bauhaus, flat roof, solid construction, single-family house with a granny flat
Basement, stories: total 2.5 stories: basement: living cellar/granny flat + utility room; ground floor: living area + office; upper floor (stepped floor): sleeping area
Number and age of people: 28 (female), 30 (male); planning for 2-3 children in about 3-4 years
Office: home office for wife
Overnight guests per year: 3–5
Open kitchen, kitchen island: open plan, preferably kitchen island (if budget allows)
Number of dining seats: 6
Balcony, roof terrace: yes, large balcony on supports connected to ground floor with garden access (depending on budget)
Garage, carport: basement carport; due to zoning plan and granny flat, 2 vehicles must fit under carport
Utility garden, greenhouse: undecided yet


House Design
Designer:
Basic design by planner from a construction company, but revised by us. Hence, the less polished own design created by me using Sweet Home 3D.

Please initially disregard the arrangement of windows, furniture, and bathroom fittings. Our main focus is on the layout and distribution of rooms across the various floors, as well as the overall concept.

About our concept:
Flexibility is one of the most important aspects of our plan. We want to use the basement initially as a granny flat and later convert it into living space for the children (hence 2 versions of the basement plan). The granny flat would be used for about 10 years before the kids move down there. When the children later leave the house and we no longer need a house of this size, it should revert back into a granny flat. Possibly later, we may also live in the granny flat ourselves and rent the upper area, but that is far in the future. The idea behind this is to alleviate the mortgage payments especially during the first 10 years, when the children are still small and one of us may not be working full-time.


What do you particularly like? Why?
The stepped floor as the parents’ area, or initially a room also for children while they are small. The layout and orientation of the kitchen/living/dining area (maybe a bit small?) facing the sun.

What do you dislike? Why?
Basement: the layout in the rear area of the granny flat (basement version 1): bathroom and bedroom are too small... Any ideas on how to gain space or redesign the granny flat so that the effort to convert to basement version 2 stays minimal.


Cost Estimate according to Architect/Planner:
440k for the house (without fittings) + 20k for balcony,
62k for garage (which was a proper garage, basemented and connected to the house on the lower ground floor)
30k for earthworks (excluding removal of excavated material)

Personal Price Limit for House including Fittings:
450k for house + fittings + ?? balcony (what more affordable options are possible for execution)
+ 30k for basement carport (self-build possible)
+ 30k earthworks (+? removal)
+ 15k landscaping

Preferred heating system: geothermal (ideally combined with photovoltaic system but probably not feasible within budget)


Why is the design as it is now? / If you had to give up, on which details or extensions
Can give up: living area size, currently approx. 195 m² (2100 sq ft). We want to reduce this somewhat to save costs. Staircase from balcony to garden.
Cannot give up: Basically, this is our dream house. If the budget isn’t enough, we will have to build significantly smaller, especially without a granny flat. The question I ask myself: How much smaller can I go with the wish for rather 3 than 2 children? Does a much smaller house justify leaving out the granny flat (granny flat = relief in the beginning when salaries are lower)? We will still need the rooms from the granny flat for the future children…


What is your most important / fundamental question about the floor plan in 130 characters?
Does our project make sense in terms of flexibility or is it nonsense and difficult to plan due to many unknowns? Did we miss fundamental things in our concept?


Thank you very much for your help

Hello!

Let me add my two cents.

First: I count 5 (!) roofs: main roof, roof terrace, left and right of the stairwell, and carport.
They all need to be sealed and drained separately.
I have built with flat roofs myself and know how complex and expensive these things can get.

Regarding the floor plan:
- How is the basement granny flat supposed to be accessed? Via the outdoor stairs at the carport?
- To me, the ratio of sleeping area to living space in the granny flat doesn’t work at all.
I would rather turn it into a three-room apartment. So, arrange the walls in a way that the children’s rooms are already planned, and with a few clever wall openings that can later be closed or opened, the granny flat could be integrated into the main apartment.
- What is the huge basement under the carport for, especially since it can only be reached from the utility room?
- I find the pantry on the ground floor unnecessary. It just causes a lot of visual clutter, and its usefulness is close to zero—at least given the size.
- I like the niche between the office and guest WC. A nice coat rack with a bench and so on should fit perfectly there.
- On the upper floor, I find the bay window for the stairwell somehow odd. I would probably move the walls of the guest room and dressing room downwards.
That would eliminate two roof surfaces right away. The house would get bigger overall, but then the entire northwest wall of the bedroom and bathroom could be pushed down as well to balance things out.
As a side effect, the roof terrace in front of the bedroom and bathroom would become large enough to use. Who knows, maybe a future spot for a hot tub or sauna? For that, it would make sense to furnish the bathroom differently.
- Windows above the bathtub seem quite impractical since you’d have to lean over the tub every time.
What is the niche between the shower and washbasin for?
- The dressing room loses most of its storage space due to the window.
- The guest room is also very awkward to furnish because of two windows and a door.

Nice house for 2 people – not suitable for a family with 2-3 children

Children spend almost the entire year outside if allowed. There is nothing more impractical than having the garden and living/cooking areas separated.
I would never build without direct access to the garden from the living space – even without children.

When do you plan to move the children to the basement? The children’s room upstairs is too small for 2-3 toddlers/babies.

Otherwise, Matte 1987 has already listed a lot.

There are even six roofs. The parking area under the carport roof also needs to be waterproofed and drained, since the basement is located underneath.
It’s worth calculating the costs directly to compare with building a garage instead.

First of all, thank you very much for the many responses.

matte1987 schrieb:

How is the basement granny flat supposed to be accessed? Via the exterior stairs at the carport?

Yes, we also don’t find that ideal yet. But a staircase between the building and the garage would further reduce the width of the plot on the south side. We would be very happy to hear alternative suggestions.

matte1987 schrieb:

The proportion between the bedroom and the living area in the granny flat doesn’t work for me at all.
I would rather make it a 3-room apartment. So, position the walls in a way that the children's rooms are basically already there and, through some cleverly placed wall openings that can later be closed or opened, integrate the granny flat into the main apartment.

We don’t like that either. But so far, we haven’t come up with a good idea. Your suggestion is definitely not bad, even though I’m not yet sure how to implement it well.

matte1987 schrieb:

What is the purpose of the huge basement under the carport, which is only accessible from the utility room?

Oops, I must have forgotten the main door to the basement. It’s actually meant to provide access from the utility room (washing machine) to the garden as well.
Due to the granny flat, the zoning plan requires two covered parking spaces. We are struggling with this and don’t know how else to solve it. In our view, a garage at street level is the only option that makes sense given the sloped site.

matte1987 schrieb:

I find the bay window at the stairwell on the upper floor a bit awkward. I would probably extend the walls of the guest room and the dressing room downwards.
That would remove two roof areas. The house becomes larger overall, but then you could also push the entire northwest wall of the bedroom and bathroom down to balance that out.
As a side effect, the roof terrace in front of the bedroom and bathroom would become large enough to be usable. Who knows, maybe a prelude to a hot tub or a sauna.

We would definitely prefer that too, especially because of the roof terrace option (*dream*). However, the zoning plan prevents us here as well, allowing only two full stories. At this location, only a recessed floor (setback level) or a gable roof is possible, which must remain within a semicircle starting from the front and rear façades. I have attached the cross-section requirement from the zoning plan.

matte1987 schrieb:

It would also make sense to arrange the bathroom furniture differently.
- I find a window over the bathtub quite impractical because you’d have to lean over the tub every time.
What is the niche between the shower and the washbasin for?
- The window in the dressing room takes up most of the storage space.
- The guest room is also extremely difficult to furnish because of two windows and the door.

We haven’t really given much thought to the furnishings/interior layout yet. I am quite sure there are better options, especially for the bathroom. My future spouse dreams of enjoying the view from the bathtub, which is why we put the window there. I am open to more good arguments against the window at that location.
Honestly, I also think the dressing room could be better; that idea was just a random thought to keep the exterior appearance harmonious. The niche could be used as a seating area when dressing... well, that can surely be improved.
The guest room remark is a good point!

But thank you very much for these comments as well.

haydee schrieb:

I would never build without direct garden access from the living area – even without children.

When do you plan to move the children to the basement? The kids’ room upstairs is too small for 2-3 toddlers/babies.

Thank you very much as well!
We have been considering this topic extensively. I have also read all the posts in the forum on this subject, but nevertheless, we came to this conclusion, although I fully understand the option you suggested.
We still plan to have direct garden access via the balcony (even if it is not yet drawn in). If we were to place the living area in the basement, this would not be possible together with the separate apartment. I also think it’s good that the children can access the garden from their bedroom, also for the reason you mentioned.

When the children will actually move downstairs is hard to say. I think it depends on their personalities as well. But we roughly aimed for 10 years of use as a separate apartment. The kids’ room is definitely too small for 3 (we acknowledge that). For 2 children, I find it okay at that age. Both my partner and I lived as two people in a similar space for a long time. And I see it now with my niece and nephew, where it also does not seem to be a problem (ages 3 and 5 in 12 m² (130 sq ft), roof slants not deducted, so the usable space feels significantly smaller). Considering that it could still work for another 2-3 years, the 10-year plan seems realistic.