ᐅ Multigenerational house (two households) on an existing plot of land
Created on: 16 Feb 2021 21:37
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EineEULE
Good evening everyone,
I have been considering this for a while now, and I would like to start defining things more concretely. Naturally, I haven’t thought through every detail yet, but I do have a rough concept. I would appreciate it if you could review it as well to check whether, due to my lack of building experience, I might have some fundamental misunderstandings or if there are certain topics I should approach differently from the start.
Situation:
I am fortunate that my family already owns a building plot of 650 square meters (7000 square feet). It was developed about 20 years ago, is located at the end of a dead-end street (private road, already paid for), and is basically just waiting to be built on. I have obtained the zoning plan from the early 1980s, which naturally imposes certain restrictions. To what extent exceptions are possible is still beyond my construction-related knowledge — if they are necessary at all.
Some key data: floor area ratio 0.4; floor space index 0.5; one full story; roof pitch 25-35 degrees Celsius (77-95 Fahrenheit); gable and hip roofs permitted; building height 3.50 meters (11.5 feet), measured from the ground floor finish level to the top of the rafter at the outer wall at roof section.
The plot is trapezoidal, approximately 30 by 20 meters (100 by 65 feet). I can prepare a sketch if needed.
I would basically build on my own, which financially should not be a problem given my income. An initial consultation with a mortgage advisor based on my first, naively estimated budget of around €500,000 (about $545,000) did not raise any major concerns, especially since I have significant equity and the plot is quite expensive, which obviously increases the overall value.
What is to be built:
The basic idea is to completely finish the larger unit to make it immediately habitable, while the smaller unit will be kept in reserve. I am not sure to what extent finishing is necessary there to maintain the building fabric. There definitely won’t be a bathroom, except for any required connections.
Of course, I have looked for inspiration among the usual prefab house providers for possible realizations. I am not sure how welcome direct references or links are here.
My question: with these key data, do I already have a fundamental planning mistake at this stage? Is a budget of about €450,000 (roughly $490,000) plus 10% contingency (for the first construction phase only) totally unrealistic? I have of course browsed through this forum seeing price per square meter figures, but I have no idea how these two construction phases would influence the costs. I understand costs vary drastically depending on fittings and finishes — but hopefully, during planning, one can get closer to more reliable values.
My approach now would be, after your plausibility check, to find a possible floor plan in the prefab house sector and based on that evaluate other building types or discuss further with the prefab house provider.
Thanks in advance 🙂
I have been considering this for a while now, and I would like to start defining things more concretely. Naturally, I haven’t thought through every detail yet, but I do have a rough concept. I would appreciate it if you could review it as well to check whether, due to my lack of building experience, I might have some fundamental misunderstandings or if there are certain topics I should approach differently from the start.
Situation:
I am fortunate that my family already owns a building plot of 650 square meters (7000 square feet). It was developed about 20 years ago, is located at the end of a dead-end street (private road, already paid for), and is basically just waiting to be built on. I have obtained the zoning plan from the early 1980s, which naturally imposes certain restrictions. To what extent exceptions are possible is still beyond my construction-related knowledge — if they are necessary at all.
Some key data: floor area ratio 0.4; floor space index 0.5; one full story; roof pitch 25-35 degrees Celsius (77-95 Fahrenheit); gable and hip roofs permitted; building height 3.50 meters (11.5 feet), measured from the ground floor finish level to the top of the rafter at the outer wall at roof section.
The plot is trapezoidal, approximately 30 by 20 meters (100 by 65 feet). I can prepare a sketch if needed.
I would basically build on my own, which financially should not be a problem given my income. An initial consultation with a mortgage advisor based on my first, naively estimated budget of around €500,000 (about $545,000) did not raise any major concerns, especially since I have significant equity and the plot is quite expensive, which obviously increases the overall value.
What is to be built:
- Two separate residential units — it’s still open whether they will be divided between ground floor and upper floor or via a granny flat / secondary unit
- About 200 square meters (2,150 square feet) of total living space, with approximately 120/80 square meters (1,300/860 square feet) planned — based on my initial research, this size might make a secondary unit somewhat complicated. Basically, 70 square meters (750 square feet) would also be sufficient, but it should not fall below that
- Either a basement or a larger living area for the bigger unit — this might sound odd, but I don’t particularly care where I can have some extra space for a small gym, hobby room, etc.
- I am indifferent about the construction method — it doesn’t have to last forever but should offer a high standard of sound insulation, especially between the two units. The surroundings are far from noisy, but I always expect the worst-case scenario
- Double garage for the first construction phase; two carport spaces planned for the second phase, but not realized immediately
- Exterior landscaping will be done by myself; the residential unit delivered turnkey
The basic idea is to completely finish the larger unit to make it immediately habitable, while the smaller unit will be kept in reserve. I am not sure to what extent finishing is necessary there to maintain the building fabric. There definitely won’t be a bathroom, except for any required connections.
Of course, I have looked for inspiration among the usual prefab house providers for possible realizations. I am not sure how welcome direct references or links are here.
My question: with these key data, do I already have a fundamental planning mistake at this stage? Is a budget of about €450,000 (roughly $490,000) plus 10% contingency (for the first construction phase only) totally unrealistic? I have of course browsed through this forum seeing price per square meter figures, but I have no idea how these two construction phases would influence the costs. I understand costs vary drastically depending on fittings and finishes — but hopefully, during planning, one can get closer to more reliable values.
My approach now would be, after your plausibility check, to find a possible floor plan in the prefab house sector and based on that evaluate other building types or discuss further with the prefab house provider.
Thanks in advance 🙂
N
nordanney17 Feb 2021 09:31EineEULE schrieb:
The basic idea is to completely finish the larger apartment so it is move-in ready, while keeping the smaller apartment in reserve. To what extent finishing work is necessary there to preserve the building structure is still unknown to me. However, no bathroom or similar facilities will be installed there—except for any essential connections, of course. Then be careful that a bank will agree to that. They usually want completed properties. If you want KfW funding, it also won’t work without a bathroom. Just something to consider.
EineEULE schrieb:
At my building site, three zoning plans intersect, and about 150 meters (490 feet) of a fourth zoning plan. This means that the next plot to the south of me is developed with 2.5 stories, the other two sides follow my zoning plan and a former agricultural operation (house with two full stories). In the line of sight (150 meters (490 feet) away), cube-style houses with flat roofs and three full stories have already been built. The issue might be that with the boundaries of the zoning plans, someone at the municipality considered and decided why up to one corner only 2 full stories and then just 1 plus attic are permitted. Your advantage is likely that the plan is quite old, and the "decision makers" from back then are no longer in office. This makes exceptions with arguments like densification, neighboring developments, different roof shapes, etc., more feasible.
To enhance the apartment with an upper floor portion (i.e., yours), a stepped floor design might also be possible, creating a kind of "penthouse feeling."
@nordanney: Thanks for the tip regarding the bathroom and KfW funding – the mortgage lender only mentioned two residential units visible on the plan as eligible for the grant. I definitely need to look into that since that’s exactly what we’re planning. Regarding financing, it’s relatively straightforward because the building plot significantly increases the overall value of the house. For example, with a hypothetical 500,000 Euro house, the plot adds 250,000 Euro in land value, which effectively counts as equity. I also have some equity myself, so the financing requirement will be around 300,000 to 350,000 Euro based on a rough calculation.
@RomeoZwo: Does it make sense to feel this out with the local municipality first? Personally, I don’t know the current decision-makers, but my parents still have “connections” there. Or should something like this be addressed directly with the district office? As I said, I would try to keep deviations as minimal as possible – a hipped roof is already planned, but not the building height or two full floors. However, in our region, that represents the minimum due to chronic land shortages. The municipality is fully built out except for the last available plot – only a few small privately owned gaps remain. Therefore, I assume there’s a good basis to argue for two residential units. Maybe I’ll just have to be persuaded to rent one out...
@RomeoZwo: Does it make sense to feel this out with the local municipality first? Personally, I don’t know the current decision-makers, but my parents still have “connections” there. Or should something like this be addressed directly with the district office? As I said, I would try to keep deviations as minimal as possible – a hipped roof is already planned, but not the building height or two full floors. However, in our region, that represents the minimum due to chronic land shortages. The municipality is fully built out except for the last available plot – only a few small privately owned gaps remain. Therefore, I assume there’s a good basis to argue for two residential units. Maybe I’ll just have to be persuaded to rent one out...
EineEULE schrieb:
I’m not planning to build a high-rise there, but currently a hip roof with two full floors is my favorite. EineEULE schrieb:
My current favorite for Apartment 1 on the ground floor includes a utility room, guest WC, kitchen, and living/dining area, with the remaining rooms on the first floor. Apartment 2 on the ground floor has its own laundry room and two well-arranged rooms around the corner. Your favorite conflicts with the zoning plan.
EineEULE schrieb:
Does it make sense to get legal advice on building regulations here? Of course, the plan is quite old, but with the generous floor area ratio (FAR) and building coverage ratio, the zoning plan does not significantly restrict house construction. You are allowed to build 260 sqm (2,800 sq ft) of floor space, which is enough for a substantial bungalow, even with a ground-level granny flat.
Just because there are other zoning plans doesn’t mean they apply; the existing one is valid for this property. The purpose of a zoning plan is to ensure a recognizable structure within an area. Yes, boundaries exist where different zones meet...
If it were so restrictive that comfortable living space is impossible, it would be worth challenging. But if you just want a standard modern townhouse, typical design, or something “nice to have,” that won’t work.
EineEULE schrieb:
Are the adjacent 2.5-story buildings an advantage? No.
EineEULE schrieb:
Am I allowed to link prefabricated houses or post floor plans here? No links, but descriptions and images are fine 🙂
I see more of a bungalow with an attached extension for a granny flat, provided the building envelope permits.
The attic could be used for a home office with a hobby room or for children’s bedrooms.
The building coverage ratio is fantastic!
You’d have to build your townhouse on another plot, but then having a ground-level granny flat might be difficult.
All well and good, but building living space half-finished that might possibly be needed in 15 years is simply a bad idea. It needs to be handled differently. For example, buying a ground-floor apartment nearby and renting it out until it is actually needed. As currently planned, nothing good can come of it.
I have taken a look at the design from Massa Haus mentioned earlier.
The ground floor could work. However, the granny flat is definitely not accessible.
A hipped roof complicates the lighting on the top floor. Two full stories are generally not possible anyway. But with a gable roof, you can accommodate the usual bedroom, two children’s rooms, and a bathroom.
I can’t imagine the building authority will approve a townhouse like this.
Develop a solid concept first, then submit a preliminary building permit application if you want to deviate from the development plan.
Please upload the site plan.
The ground floor could work. However, the granny flat is definitely not accessible.
A hipped roof complicates the lighting on the top floor. Two full stories are generally not possible anyway. But with a gable roof, you can accommodate the usual bedroom, two children’s rooms, and a bathroom.
I can’t imagine the building authority will approve a townhouse like this.
Develop a solid concept first, then submit a preliminary building permit application if you want to deviate from the development plan.
Please upload the site plan.