ᐅ New Construction: Basement or Larger Ground Floor, Attic Conversion?
Created on: 6 Dec 2010 20:27
R
rausausBerlinR
rausausBerlin6 Dec 2010 20:27Hello,
I have read quite a bit here about whether to have a basement or not, but unfortunately, I am no wiser.
We want to build and are unsure, especially regarding costs, whether we should go with a basement, a larger ground floor than a bungalow, or a classic single-family house with attic space accessible via a knee wall. There are a few factors to consider:
- It will be solid construction
- Living area around 110-120sqm (1184-1292 sq ft), two children, guest toilet, L-shaped floor plan
- Interior work such as painting, carpentry, drywall, and flooring will be done by us
- Possibly funding through KfW
- Brandenburg
The plot is 860sqm (0.21 acres) with about 20m (65 ft) frontage to the street. A setback of 3m (10 ft) must be deducted on each side. Utilities come onto the plot from the street over a width of about 10m (33 ft). The soil is sandy and dry even at 2.7m (9 ft) depth. In front of the plots are old lime trees, which in the neighboring house even press into the basement from below (i.e., from 2.7m depth).
The part of the plot where the house is planned used to have a partly basemented building. Although the excavation was backfilled, it was not compacted.
The house should not be built at ground level but slightly raised (about 50cm (20 inches)).
So, if I basement about one-third of the footprint parallel to the street, in my opinion, the advantages are:
- The roots are initially cut off
- All utilities are not in living spaces but accessible and hidden in the basement
- The basement excavation fill ends up under the rest of the house, which will be slightly raised
- No need to compact the old excavation pit
- Convenient space for a pantry, heating system, and a 25sqm (269 sq ft) hobby room (large hi-fi system, not child-friendly, roof slopes are acoustically poor)
Downside: A basement extends the shell construction and is supposedly expensive. But how expensive? What should I expect for a 4x10m (13x33 ft) basement (interior dimensions) without moisture issues? More than the cost of about 15sqm (161 sq ft) extra floor area? Shell only inside, only the hobby room heated, only skylights on the ~10m (33 ft) street frontage...
If I skip the basement and make the attic sufficiently convertible by having a knee wall high enough, the problem is the house will be on the southwest side of the plot — so a tall house will cast shade on the property...
Please share your thoughts on this.
I have read quite a bit here about whether to have a basement or not, but unfortunately, I am no wiser.
We want to build and are unsure, especially regarding costs, whether we should go with a basement, a larger ground floor than a bungalow, or a classic single-family house with attic space accessible via a knee wall. There are a few factors to consider:
- It will be solid construction
- Living area around 110-120sqm (1184-1292 sq ft), two children, guest toilet, L-shaped floor plan
- Interior work such as painting, carpentry, drywall, and flooring will be done by us
- Possibly funding through KfW
- Brandenburg
The plot is 860sqm (0.21 acres) with about 20m (65 ft) frontage to the street. A setback of 3m (10 ft) must be deducted on each side. Utilities come onto the plot from the street over a width of about 10m (33 ft). The soil is sandy and dry even at 2.7m (9 ft) depth. In front of the plots are old lime trees, which in the neighboring house even press into the basement from below (i.e., from 2.7m depth).
The part of the plot where the house is planned used to have a partly basemented building. Although the excavation was backfilled, it was not compacted.
The house should not be built at ground level but slightly raised (about 50cm (20 inches)).
So, if I basement about one-third of the footprint parallel to the street, in my opinion, the advantages are:
- The roots are initially cut off
- All utilities are not in living spaces but accessible and hidden in the basement
- The basement excavation fill ends up under the rest of the house, which will be slightly raised
- No need to compact the old excavation pit
- Convenient space for a pantry, heating system, and a 25sqm (269 sq ft) hobby room (large hi-fi system, not child-friendly, roof slopes are acoustically poor)
Downside: A basement extends the shell construction and is supposedly expensive. But how expensive? What should I expect for a 4x10m (13x33 ft) basement (interior dimensions) without moisture issues? More than the cost of about 15sqm (161 sq ft) extra floor area? Shell only inside, only the hobby room heated, only skylights on the ~10m (33 ft) street frontage...
If I skip the basement and make the attic sufficiently convertible by having a knee wall high enough, the problem is the house will be on the southwest side of the plot — so a tall house will cast shade on the property...
Please share your thoughts on this.
B
Bauexperte7 Dec 2010 10:41Hello,
The choice of building material is initially secondary, as there are factors that apply equally to all construction methods: a basement is always the most expensive option, and an L-shaped bungalow leads to a higher initial cost due to the larger roof area. Using the attic space by extending the stairwell opening, routing installations, and fully boarding the area is typically around EUR 7,000 +/- EUR 1,000 for a standard-sized detached house.
If you build without a basement, you will likely need soil replacement and compaction because the new house cannot be constructed on „naturally settled“ ground.
That, in turn, depends on the text-based zoning requirements for the plot and the existing elevation of the adjacent street; there are usually limits within which you must stay. If 50 cm (20 inches) is within tolerance, you should calculate additional costs for the excavation, including working space, multiplied by 50 cm (20 inches).
The advantages will be limited, as a partial basement—contrary to common belief—will only be marginally cheaper than a full basement.
South-facing plots have the „disadvantage“ that a significant portion of the site will be shaded; are you perhaps overestimating the sun’s path and the time you spend in the garden?
Best regards
rausausBerlin schrieb:
We want to build and are uncertain about the costs, whether to build with a basement, a larger footprint bungalow, or a classic detached house with potential for expansion via knee walls…
The choice of building material is initially secondary, as there are factors that apply equally to all construction methods: a basement is always the most expensive option, and an L-shaped bungalow leads to a higher initial cost due to the larger roof area. Using the attic space by extending the stairwell opening, routing installations, and fully boarding the area is typically around EUR 7,000 +/- EUR 1,000 for a standard-sized detached house.
rausausBerlin schrieb:
The plot where the house is to be built once had a partially basemented building; the pit was backfilled but not compacted.
If you build without a basement, you will likely need soil replacement and compaction because the new house cannot be constructed on „naturally settled“ ground.
rausausBerlin schrieb:
The house is not to be built at ground level but slightly elevated (~50cm (20 inches)).
That, in turn, depends on the text-based zoning requirements for the plot and the existing elevation of the adjacent street; there are usually limits within which you must stay. If 50 cm (20 inches) is within tolerance, you should calculate additional costs for the excavation, including working space, multiplied by 50 cm (20 inches).
rausausBerlin schrieb:
If I basement one-third of the footprint parallel to the street, I believe I have the following advantages
The advantages will be limited, as a partial basement—contrary to common belief—will only be marginally cheaper than a full basement.
rausausBerlin schrieb:
If I skip the basement and make the upper floor expandable with sufficient knee wall height? Unfortunately, the future house is located in the southwest of the plot — so we will shade part of the yard with a tall house
South-facing plots have the „disadvantage“ that a significant portion of the site will be shaded; are you perhaps overestimating the sun’s path and the time you spend in the garden?
Best regards
Personally, I would ask what benefits a basement would bring you or what you plan to use it for. In my opinion, basements are becoming outdated, but I realize I am quite in the minority with that view.
100-120m² (1076-1292 sq ft) for two people or more?
Isn’t the house freely positionable on the plot?
The plot isn’t small, but an L-shaped bungalow naturally uses more space compared to a one-and-a-half-story detached house (for 110m² (1184 sq ft) living area, around 85m² (915 sq ft) footprint).
How expensive a basement will be depends of course on many location factors, but if you need a lot of unused space, it’s often cheaper to simply enlarge the house or add a separate garage or hobby building.
100-120m² (1076-1292 sq ft) for two people or more?
Isn’t the house freely positionable on the plot?
The plot isn’t small, but an L-shaped bungalow naturally uses more space compared to a one-and-a-half-story detached house (for 110m² (1184 sq ft) living area, around 85m² (915 sq ft) footprint).
How expensive a basement will be depends of course on many location factors, but if you need a lot of unused space, it’s often cheaper to simply enlarge the house or add a separate garage or hobby building.
R
rausausBerlin8 Dec 2010 14:24Thanks first of all for the inputs.
The unique shape of the house results from the neighboring buildings and local regulations. Building is only allowed in the middle of the plot, and orientation towards the street is "customary." The left neighbor’s house is quite tall, with 2 floors plus a fully converted attic, and behind it there is a carpenter’s workshop. The right house is built right up to the property line, and behind it is a shed (the plot belongs to my in-laws). Hopefully, I can manage a sketch this evening.
That’s why it’s an L-shape, opening towards the parents and closing off the plot towards the workshop.
The house is designed for 4 people (2 toddlers), so the planned approximately 110 sqm (1,184 sq ft) of floor area is quite fully utilized. Although there is still a 20 sqm (215 sq ft) shed planned between the house and the parents’, it will be unheated and already occupied by our bikes, workbench, and garden tools, so likely no further use potential.
Until now, I have only lived in houses with basements and find that very practical—building services out of sight, clear spatial separation of functions, and still a roof as a flexible expansion reserve. However, I’m not sure about the financial implications or if there might be alternative solutions I’m overlooking.
For a basement covering about one-third to one-half of the footprint in a rectangular shape without an external staircase, only lightly insulated and masonry-built, with 2 solid interior walls, unfinished interior shell, precast concrete ceiling, and 3 or 4 skylights, where would I end up cost-wise? €300/sqm (about $320), €400, or rather €500?
The construction effort for a slab foundation must be significantly higher than for the floor of a basement, right? And every additional square meter of ground floor surely adds about €1,200 (approximately $1,280) to the cost as well...
The unique shape of the house results from the neighboring buildings and local regulations. Building is only allowed in the middle of the plot, and orientation towards the street is "customary." The left neighbor’s house is quite tall, with 2 floors plus a fully converted attic, and behind it there is a carpenter’s workshop. The right house is built right up to the property line, and behind it is a shed (the plot belongs to my in-laws). Hopefully, I can manage a sketch this evening.
That’s why it’s an L-shape, opening towards the parents and closing off the plot towards the workshop.
The house is designed for 4 people (2 toddlers), so the planned approximately 110 sqm (1,184 sq ft) of floor area is quite fully utilized. Although there is still a 20 sqm (215 sq ft) shed planned between the house and the parents’, it will be unheated and already occupied by our bikes, workbench, and garden tools, so likely no further use potential.
Until now, I have only lived in houses with basements and find that very practical—building services out of sight, clear spatial separation of functions, and still a roof as a flexible expansion reserve. However, I’m not sure about the financial implications or if there might be alternative solutions I’m overlooking.
For a basement covering about one-third to one-half of the footprint in a rectangular shape without an external staircase, only lightly insulated and masonry-built, with 2 solid interior walls, unfinished interior shell, precast concrete ceiling, and 3 or 4 skylights, where would I end up cost-wise? €300/sqm (about $320), €400, or rather €500?
The construction effort for a slab foundation must be significantly higher than for the floor of a basement, right? And every additional square meter of ground floor surely adds about €1,200 (approximately $1,280) to the cost as well...
B
Bauexperte12 Dec 2010 11:45Hello,
More likely around €500.00.
A slab foundation is always necessary, whether you build with or without a basement...
Kind regards
rausausBerlin schrieb:
With a one-third to one-half basement in a rectangular shape without an external staircase, lightly insulated and built with masonry, 2 solid interior walls, unfinished interior shell, prefabricated concrete ceiling, 3 or 4 skylights, where would that put me? €300/sqm? 400? More like 500?…
More likely around €500.00.
rausausBerlin schrieb:
The construction effort for a slab foundation is definitely higher than the foundation for a basement, right? And every additional square meter on the ground floor will probably cost about €1200...
A slab foundation is always necessary, whether you build with or without a basement...
Kind regards
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