Cost estimation review for two-family house (450 sqm)

  • Erstellt am 2017-04-18 15:15:54

sichtbeton82

2017-04-18 15:15:54
  • #1
Two-family house with granny flat – Description of construction project

Development plan / restrictions:

· Size of the plot: 1,200 m² (18m wide)
· Slope: south-facing slope, street to the north
· Plot ratio: 0.3
· Floor area ratio: 0.6
· Building envelope, building line and boundary: see “Enlargement of building envelope”
· Edge development: garages
· Number of parking spaces: 3 required according to building authority
· Number of stories: see 3.1 of the statute (two stories from the valley side)
· Type of construction: open construction
· Building setback: 3m
· Roof shape: ridge roofs 15-30°, hipped roofs to be avoided etc. see statute
· Maximum heights/limitations: see 5.2 of the statute (eaves 3m single-story)
· Exterior design: see 6. of the statute

Requirements of the clients

In advance: The clients (1982 male, 1988 female and two children 2014 female, 2016 male) shall live on two floors (basement and ground floor). A third children’s room should also be included in the planning. On the third floor (e.g. attic) the parents as well as the sister of the female client are to move in. The apartment should be barrier-free (accessible).

· Style: Bauhaus (optional exposed concrete),
· Roof shape: with large south-facing side (solar, photovoltaics). For example, a gable roof.
· Building type: two-family house
· Basement, floors: basement, ground floor, attic
· Number of people, ages see above: (2+3 in basement, ground floor / 2+1 in attic)

· Open or closed architecture: open staircase ground floor/basement
· Conservative or modern design: modern
· Kitchen: open kitchen, cooking island (at least on ground floor)
· Fireplace: optional (preferably with external flue for cost reasons)
· Balcony, roof terrace: probably reasonable on all three floors given the view
· Parking spaces: if possible carports that can later be converted into garages (temporary cost saving)
· Heating/thermal technology: solar thermal in combination with air-to-air heat pump (underfloor heating), optional photovoltaics

· Technology:
· Energy efficiency: at least KfW70 (attic KfW55)
· High sound insulation (especially to ceiling of granny flat)

*** The plot is on a south-facing slope. The ground floor lies within the building envelope max. to the south. The upper floors (ground floor and attic) are each recessed according to the terraces (2.5m / 2.75m).

The following net floor areas result:

Basement 01 5.67
Basement 02 22.15
Storage room 6.77
Hallway 19.26
Bathroom 6.59
Children’s room 01 19.62
Children’s room 02 19.62
Children’s room 03 19.57
Total 119.25

Ground floor (m²)
Bathroom 10.58
Dressing room 8.06
Bedroom 16.63
WC 1.90
Entrance area 3.51
Hallway 10.75
Living/cooking 61.55
Terrace 26.97
Total 139.95

Attic (m²)
Bedroom 01 12.62
Bedroom 02 14.77
Bathroom 7.19
Utility room 9.04
Entrance area 4.36
Hallway 9.11
Kitchen living 28.88
Terrace 35.98
Total 121.95

In total thus 381.15 m² net floor area (including terraces). 318.20 m² excluding terraces.
In total thus 452.27 m² gross floor area (including terraces). 386.27 m² excluding terraces.

The following costs according to DIN 276 are assumed:

200 Site preparation and development: 13,000
300 Building construction - building structures: 343,250
400 Building construction - technical systems: 135,600
300+400 Building construction - total: 479,120
500 Outdoor facilities: 38,448 (for 432 m²)
700 Additional building costs: 95,824.00
Total: 626,392

This results in a unit price per m³ of constructed volume (at 3m story height!!! including terraces!!!) of 353.13 EUR (incl. VAT) without additional building costs. Is this realistic?

Thank you very much!
 

sichtbeton82

2017-04-19 07:16:34
  • #2
... forget the most important thing! Simple to medium equipment.
 

sichtbeton82

2017-04-20 10:42:40
  • #3
For example, if I use a house construction cost calculator from "bauen und heimwerken" with the following values:

Building type: single-family house
Living area: 350 m² (actually 290 plus 60 roof terraces)
Basement area: 30 m²
Building geometry: lively
Number of floors: 3
Roof shape: gable
Floor plans: open, clear structure
Foundation: deep foundation
Building construction: solid
Prefabricated parts: no
Conservatory: no
Glass area proportion: a lot
Fittings/finishing: normal
Access to construction site: normal
Location: outside
Economic situation: high

I get:
300 Building - Construction: 309,366 net
400 Building - Technical installations: 54,588 net
300+400 Building - total: 433,105 (i.e. 46,015 cheaper)

There is also a similar calculator at "deutscherbau", which is a bit more detailed (e.g. selectable federal state, roof covering, etc.). Also here with 350 m² living area (including the 60 m² roof terraces). There, the total price is about 590,000 (i.e. about 36,000 cheaper).

Thus, with two different approximation methods, I come up with lower values (even though, for example, I included more living area).

What do you think about these "calculators"?
 

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