Calculation of a prefabricated house

So, thanks for the answers and suggestions.

1) we will not undertake any own work
2) Basement construction > see text below.
3) The children's room also has access to the master bathroom according to the floor plan. Maybe the wording was not quite right.

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We had our initial consultation today.

We were shown a 3D floor plan that presents the technical room in the garage extension as one option.
This way, no space is lost on the base plate and the ground floor room can even be used as a guest room. This actually allows us to avoid basement construction.
The roof structure can be easily climbed, as it will have a height of 190cm.
Also, no construction contract has been presented to us yet.

In September, we will do a trial overnight stay at a show house at the factory, and at the same time, we can view a preliminary selection for further cost calculation and visit the production.
Furthermore, we have scheduled an appointment to visit a FischerHaus construction site during the erection of the shell.

Payment agreement is regulated as follows:
5% of the contract amount upon house order
65% of the contract amount after house erection
30% after handover of the keys

He also broke down the costs for the floor plan.
House Kfw40, turnkey. 146sqm, 2096 €/sqm = 306,083 €

Total: 306,083 €

Special requests without selection.
Exterior blinds 1.10 x 1.19 m: 6*354 € = 2,124 €
Exterior blind 0.72 x 0.865 m: 1*295 € = 295 €
Exterior blinds 1.975 x 2.11m: 6*644 € = 3,864 €
Loxone Intercom: 1*1883 € = 1,883 €
Double washbasin including connections: 1*1500 € = 1,500 €
Cooling function heating: 1*1945 € = 1,945 €
Rain shower: 1* 800 € = 800 €
Terrace sliding door 3.97*2.11m*: 1*2070 €
Spotlights swivel and dimmable including installation + cables: 37*107 € = 3,959 €

Total: 18,440 €

All other items can be purchased through FischerHaus or contracted independently.
He gave us experience values so we can calculate better.
Photovoltaic: 6.12 KWp + battery storage 5.5 KW = 20,916 €
Base plate: 95sqm, 218 €/sqm = 20,708 €
Earthworks excavation: 20,000 €
Soil survey: 1,500 €
Surveying: 2,000 €
Building permit: 3,221 €
House connections: (telecommunications, electricity, wastewater, rainwater, fresh water) = 12,000 €
Other incidental construction costs: (construction power, construction water, insurance, etc.) = 1,000 €
Double garage: 6x9m, 2 parking spaces, at 15,500 € each = 31,000 €
Garage substructure: 54sqm, 100 € = 5,400 €
Outdoor facilities: approx. 5% of house price = 15,304 €

Total: 133,049 €

Overall, if we were to build like this, the calculation does not fit our budget framework.
Because of this, we will receive a new adjusted offer for a single-family house of 130sqm.
Here and there we are also thinking about possibly retrofitting some positions at a later time.
For example:
- Cooling function of the air heat pump (apparently feasible)
- Garage
- Outdoor facilities
- Reduction of spotlights
- Ground floor exterior blinds, upper floor roller shutters
- Photovoltaics
- Battery storage
- Smart home
- a smaller terrace sliding door

Alternatively, we could indeed get a bit more budget from our bank, but this still needs to be clarified.

I could imagine that both downsizing and "trimming" in one place or another will become necessary in order to stay within the budget, although I maintain that implementing the planned room program will be difficult with at least 130 square meters. If you separate the utility room [HAR] into the garage extension, you do gain space inside the house, but then you have to upgrade the utility room because otherwise it is not allowed to be used for that purpose. So it probably won’t be much cheaper – and you lose the space in the garage extension.

Would you perhaps like to show the current floor plan? Or have I simply overlooked it so far?

I don't think the budget is enough, but you can already see that from the initial consultation. We are currently building in a rural area, 133 sqm + approximately 25 sqm almost finished attic and a double garage, and our price already starts with a 5, even though our plot was one third cheaper. We only have one roller shutter over a 4 meter front, photovoltaic 7.4 without battery, KFW 55 and no smart home, just the cheap alternative merten wiser which controls the roller shutters and 3 light switches. We do have some spots, but they are surface-mounted. We are doing the outdoor facilities ourselves and the material alone is already over 10,000.00.

He also itemized the costs for the floor plan.
KfW40 house, turnkey. 146 sqm, €2096/sqm = €306,083

€


Special requests without sampling.
Raffstore 1.10 x 1.19 m: 6*€354 = €2124
Raffstore 0.72 x 0.865 m: 1*€295 = €295
Raffstore 1.975 x 2.11 m: 6*€644 = €3864
Loxone intercom: 1*€1883 = €1883
Double washbasin including connections: 1*€1500 = €1500
Heating cooling function: 1*€1945 = €1945
Rain shower: 1*€800 = €800
Terrace sliding door 3.97*2.11 m: 1*€2070
Spotlights rotatable and dimmable including installation + cable: 37*€107 = €3959

Total: €18,440

Cool!
My calculation matches that of the builder, even if I calculate differently as an amateur:

€2100/sqm living space
€20,000 special requests and equipment
€70,000 basement
€60,000 technical upgrades (KfW40, photovoltaics, smart home, etc.)
I’d say: Your wishes definitely come from the „I-want-everything“ box.
There is a reason why some houses look quite „bare“ inside and out to others, or why a normal light switch has to do. Also, most wouldn’t have to discuss the pros and cons of a basement if the budget were an unlimited treasure chest or if the basement cost nothing. Add another third for living space expansion.
Skip the freezer gadgetry, you can retrofit that later. Also, the basement costs more than it’s worth; an expanded attic could be an alternative for additional rooms.
I remember someone here had the dream of a shisha room in the basement, Grym or Baugrym... Stylish man cave... in the end it was built without fuss and without a basement: when you have kids, you don’t have time for things like that anyway.

Cooling function heating: 1*1945 € = 1945 €

A house seller once told us that reversible heat pumps and ventilation systems are not Kfw 40 Plus compatible. No idea if that's really true.

Photovoltaic: 6.12 KWp + battery storage 5.5 KW = 20916€

The photovoltaic system is too small or the battery storage too large. Besides, the system is way too expensive.

Double garage: 6x9m, 2 parking spaces, at 15500€ each = 31000 € Substructure garage: 54 sqm, 100 € = 5400 €

So our single garage with an attached 7 sqm storage room costs 38 kEUR. I find 36.4 kEUR for a double garage a bit low. How is it supposed to be executed? Directly attached to the house or somewhere separate (= prefabricated garage)?

You are tight on money but you want KfW 40, I never understood that by the way [Technikraum] outside the shell is not allowed