ᐅ Single-family home with a granny flat on a 450 sqm sloped lot
Created on: 9 Feb 2022 11:44
K
Kristijan
Hello everyone,
Until now, I have only been a silent reader here, but I would like to present our own house concept for discussion. I am hoping for candid criticism, as well as your ideas and suggestions.
We are a blended family with four children (three are usually at home) and we are planning to build a single-family house with a secondary apartment in NRW. At the beginning of last year, we bought a sloped lot in a typical new development area and have since worked with an architect to develop a house concept. We designed a very simple building form (four walls and a roof) with an efficient floor plan. We sent our plans to several prefabricated house companies, asking for cost estimates, hoping that our budget might allow for potential expansion of the house. Now, faced with their offers, we have to admit that even our smallest possible floor plan exceeds our budget. The budget is about 550,000 euros for the house including additional construction costs (excluding the land). With the secondary apartment, we had hoped to double the KfW funding in the KfW 40 EE class with 67,500 euros to increase the budget. But it is what it is.
Perhaps our preliminary cost estimate was a bit naive. In any case, we are currently reconsidering the concept and are considering doing without a basement.
And now, please, fire away with your frank criticism and unvarnished truths. 🙂
Zoning Plan / Restrictions
Plot size: 450 sqm (4,844 sq ft)
Slope: Yes, north-facing slope (from the street toward south-southwest) with about 1.5 m (5 feet) elevation within the building envelope (1 meter (3 feet) within the planned footprint) rising
Floor area ratio (FAR): ?
The zoning plan does not provide this information
Building area ratio (site coverage): 0.4
Building envelope, building line and boundary: 19.5 m (64 feet) wide (street side), at the rear 17 m (56 feet) wide and 14 m (46 feet) deep
Edge development: Yes
Number of parking spaces: 2 for the main unit and 1 for the secondary apartment
Number of floors: 2.5
Roof type: Gable roof
Architectural style: Traditional
Orientation: Ridge runs from west-northwest to east-southeast
Maximum heights / limits: Maximum ridge height 9.5 m (31 feet) above finished ground floor level (this may exceed the reference street level by max. 0.5 m (1.5 feet))
Other requirements: Side setbacks 3 m (10 feet), setback from the street 3.5 m (11.5 feet)
Client Requirements
Architectural style and building type: Simple, economical building form with a gable roof
Basement, floors: Basement with secondary apartment, total 2.5 floors
Number of people, ages: Household of 5-6 people: parents aged 38 and 36, four children aged 7, 4, 2x 2 years. Family planning went a bit beyond the target and is now complete 🙂 plus grandmother in the basement apartment
Space needs on ground / upper floors: About 140-150 sqm (1,500-1,615 sq ft): kitchen, living room, 1 bedroom, 3 children’s bedrooms, 1 guest/office/patchwork room, 2 bathrooms
Utility room in the basement
Office: 1 flexible room required
Guests per year: About 10
Open or closed layout: Form follows function
Conservative or modern style: Hm, what exactly is meant here?
Open kitchen, kitchen island: Open kitchen adjacent to dining area (a kitchen island is welcome here), but closed off toward the living room
Number of dining seats: 6-8
Fireplace: No
Music / stereo wall: TV in the living room
Balcony, roof terrace: Covered terrace facing the garden with pass-through window from the kitchen
Garage, carport: Carport with green roof and additional storage space would be ideal
Vegetable garden, greenhouse: Small kitchen garden along the property boundary
House Design
Designer: Independent architect working with a prefabricated house company and DIY elements
What do you particularly like? Efficient use of space. Despite compactness, all requirements regarding space needs, especially number of rooms, are met
What do you dislike? Especially the ground floor could be more generous, the basement or storage spaces could be larger
Price estimate (according to architect): Not available
Price limit including fittings: 550,000 euros plus KfW funding if still available
Preferred heating system: Air-to-water heat pump
If you have to sacrifice something, which details or extensions would you give up?
-can give up: Reluctantly on the separate parents’ area
The secondary apartment is also under discussion
The sliding doors on the ground floor are due to a coordination error and can be removed
-can not give up: Number of rooms
Why did the design turn out the way it is?
We basically created the design ourselves. The architect later made some optimizations. Our main focus was to accommodate all room requirements within a compact floor plan on a small plot. Furthermore, as parents of four children, we wanted our own small private space.
What is the most important / fundamental question about the floor plan, summarized in 130 characters?
Is our house concept failing due to our budget expectations? What would you do differently and why?
Until now, I have only been a silent reader here, but I would like to present our own house concept for discussion. I am hoping for candid criticism, as well as your ideas and suggestions.
We are a blended family with four children (three are usually at home) and we are planning to build a single-family house with a secondary apartment in NRW. At the beginning of last year, we bought a sloped lot in a typical new development area and have since worked with an architect to develop a house concept. We designed a very simple building form (four walls and a roof) with an efficient floor plan. We sent our plans to several prefabricated house companies, asking for cost estimates, hoping that our budget might allow for potential expansion of the house. Now, faced with their offers, we have to admit that even our smallest possible floor plan exceeds our budget. The budget is about 550,000 euros for the house including additional construction costs (excluding the land). With the secondary apartment, we had hoped to double the KfW funding in the KfW 40 EE class with 67,500 euros to increase the budget. But it is what it is.
Perhaps our preliminary cost estimate was a bit naive. In any case, we are currently reconsidering the concept and are considering doing without a basement.
And now, please, fire away with your frank criticism and unvarnished truths. 🙂
Zoning Plan / Restrictions
Plot size: 450 sqm (4,844 sq ft)
Slope: Yes, north-facing slope (from the street toward south-southwest) with about 1.5 m (5 feet) elevation within the building envelope (1 meter (3 feet) within the planned footprint) rising
Floor area ratio (FAR): ?
The zoning plan does not provide this information
Building area ratio (site coverage): 0.4
Building envelope, building line and boundary: 19.5 m (64 feet) wide (street side), at the rear 17 m (56 feet) wide and 14 m (46 feet) deep
Edge development: Yes
Number of parking spaces: 2 for the main unit and 1 for the secondary apartment
Number of floors: 2.5
Roof type: Gable roof
Architectural style: Traditional
Orientation: Ridge runs from west-northwest to east-southeast
Maximum heights / limits: Maximum ridge height 9.5 m (31 feet) above finished ground floor level (this may exceed the reference street level by max. 0.5 m (1.5 feet))
Other requirements: Side setbacks 3 m (10 feet), setback from the street 3.5 m (11.5 feet)
Client Requirements
Architectural style and building type: Simple, economical building form with a gable roof
Basement, floors: Basement with secondary apartment, total 2.5 floors
Number of people, ages: Household of 5-6 people: parents aged 38 and 36, four children aged 7, 4, 2x 2 years. Family planning went a bit beyond the target and is now complete 🙂 plus grandmother in the basement apartment
Space needs on ground / upper floors: About 140-150 sqm (1,500-1,615 sq ft): kitchen, living room, 1 bedroom, 3 children’s bedrooms, 1 guest/office/patchwork room, 2 bathrooms
Utility room in the basement
Office: 1 flexible room required
Guests per year: About 10
Open or closed layout: Form follows function
Conservative or modern style: Hm, what exactly is meant here?
Open kitchen, kitchen island: Open kitchen adjacent to dining area (a kitchen island is welcome here), but closed off toward the living room
Number of dining seats: 6-8
Fireplace: No
Music / stereo wall: TV in the living room
Balcony, roof terrace: Covered terrace facing the garden with pass-through window from the kitchen
Garage, carport: Carport with green roof and additional storage space would be ideal
Vegetable garden, greenhouse: Small kitchen garden along the property boundary
House Design
Designer: Independent architect working with a prefabricated house company and DIY elements
What do you particularly like? Efficient use of space. Despite compactness, all requirements regarding space needs, especially number of rooms, are met
What do you dislike? Especially the ground floor could be more generous, the basement or storage spaces could be larger
Price estimate (according to architect): Not available
Price limit including fittings: 550,000 euros plus KfW funding if still available
Preferred heating system: Air-to-water heat pump
If you have to sacrifice something, which details or extensions would you give up?
-can give up: Reluctantly on the separate parents’ area
The secondary apartment is also under discussion
The sliding doors on the ground floor are due to a coordination error and can be removed
-can not give up: Number of rooms
Why did the design turn out the way it is?
We basically created the design ourselves. The architect later made some optimizations. Our main focus was to accommodate all room requirements within a compact floor plan on a small plot. Furthermore, as parents of four children, we wanted our own small private space.
What is the most important / fundamental question about the floor plan, summarized in 130 characters?
Is our house concept failing due to our budget expectations? What would you do differently and why?
K
Kristijan9 Feb 2022 13:17Tamstar schrieb:
If you move into the basement apartment (having your own space is completely understandable to me), because grandma doesn’t necessarily have to come along (it’s not senior-friendly anyway, everything is quite cluttered) and the non-permanent child moves to the ground floor, you could simplify the floor plan a bit—have you tried that?
The full bathroom on the ground floor could then be completely removed, and the bathtub would go into the already fairly empty kids’ bathroom. Nevertheless, I find this approach interesting. You could still rent out the granny flat once the kids have moved out, and have more space upstairs. I would need to run the numbers. Would a saving of an estimated 10cm (5 inches) of floor space make it possible to convert the basement into living space within our budget?
K
Kristijan9 Feb 2022 13:19Kristijan schrieb:
In my rough calculation, the estimated 350 euros monthly rent (cold rent) at an assumed interest rate of 2% and an equally high repayment rate generated about 100,000 euros of additional financing volume. This roughly corresponds to the finishing costs of the basement level. Therefore, the monthly financial burden would remain about the same, assuming the plan includes a basement. The calculation looks different in my opinion if you skip the basement and build on a slab foundation instead. However, with my floor plan, I would need expensive basement replacement rooms, and the suggestion from Hausbautraum20 to have the utility room on the ground floor could be the solution.
It is questionable whether our plot can accommodate a slab foundation. I fear that the cost advantage of the slab could be offset by additional expenses for landscaping. What I mean is:
Without the income from the granny flat, the budget would shrink by about 100,000 euros.
B
Benutzer2009 Feb 2022 13:49Kristijan schrieb:
In my rough calculation, the estimated 350 euros cold rent with an assumed interest rate of 2% and an equally high repayment generated about 100,000 euros additional financing volume. This roughly corresponds to the finishing costs of the basement level. Therefore, the monthly financial burden would remain about the same under the assumption of planning with a basement. In my view, the calculation is different if you forgo the basement and build on a slab foundation. In that case, I would need expensive basement replacement rooms for my floor plan, and the suggestion from Hausbautraum20 with the utility room on the ground floor might be the solution. Kristijan schrieb:
What I want to say is:
Without the rental income from the secondary apartment, the budget would shrink by about 100,000 euros. And without the expensive basement, it would be a break-even scenario. However, the net cold rent is not what ultimately ends up in your pocket — taxes, operating costs (maintenance/renovation, etc.) come into play.
Without the secondary apartment and only with a slab foundation (if feasible), you also save additional heating and ventilation systems. Plus, by giving up KfW 40 energy standard—which you would only do because of subsidies—the house gets significantly smaller. At the end, perhaps you also avoid having to deal with inconvenient (external) tenants...
K
Kristijan9 Feb 2022 15:07@Benutzer200
Regarding building on a slab foundation, we first need to wait for our soil report. It was suggested that the ground might be soft and that a basement could potentially be beneficial. Another question is how this relates to the slab foundation and the slope.
Regarding building on a slab foundation, we first need to wait for our soil report. It was suggested that the ground might be soft and that a basement could potentially be beneficial. Another question is how this relates to the slab foundation and the slope.
How many square meters is it? Depending on the area, 2,500€/m² (approximately $2,700/ft²) might still be enough in more expensive neighborhoods, but with better equipment or finishes, it can be significantly higher.
On top of that, there are the full additional costs as well as the landscaping.
All in all, you won’t get more than 120-150m² (about 1,300-1,600 ft²) in the cheaper areas.
So you will have to make compromises and reduce the size.
Please write a bit about your financial situation.
A granny flat or accessory dwelling unit is generally not cost-effective because of the construction costs. If you don’t mind having strangers in the house, a separate apartment might be a better option.
On top of that, there are the full additional costs as well as the landscaping.
All in all, you won’t get more than 120-150m² (about 1,300-1,600 ft²) in the cheaper areas.
So you will have to make compromises and reduce the size.
Please write a bit about your financial situation.
A granny flat or accessory dwelling unit is generally not cost-effective because of the construction costs. If you don’t mind having strangers in the house, a separate apartment might be a better option.
Kristijan schrieb:
Floor area ratio? The development plan doesn’t provide any information on that.
Plot ratio 0.4 The combination of mentioning floor area ratio and not plot ratio is "unusual"; it’s more common the other way around.
Kristijan schrieb:
We basically created the design ourselves. Then, the architect made some optimizations here and there. For a non-professional plan, the design is actually quite good, but it’s already quite detailed to only now check whether it fits the budget—especially considering that fundamental decisions, like whether grandma will move in, are still unresolved.
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