ᐅ Cost Estimate for a Prefabricated House with Owner-Performed Work
Created on: 14 Apr 2025 09:56
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PurpleBeeP
PurpleBee14 Apr 2025 09:56Hello everyone,
In our area (greater Stuttgart), there is a 500 sqm (5,382 sq ft) plot of land for sale in a very good location. The price is 450,000 €. The plot is serviced and ready for immediate construction. Building on the plot alone is financially absolutely not feasible for us (both 32 years old, one child + one planned), so we would like to build a semi-detached house. My sister and brother-in-law with two children are also interested in building, and we can well imagine doing it together.
My brother-in-law is a civil and landscape construction contractor with his own company (excavators, trucks, etc.), and we think we are quite skilled with DIY work. We also have access to painters and heating technicians within the family, a friend who is an architect, and if needed access to trained or affordable helpers.
We can well imagine taking on at least the entire interior finishing ourselves (or subcontracting if necessary). To get the ball rolling, I would like to make a first rough cost estimate. The prefabricated house should come as a shell with exterior facade, windows, front door, staircase, roof, and connections included. This and other items (e.g., electrical work) would of course need to be finalized with the supplier. I would also likely subcontract the foundation slab to be safe. We might take on the earthworks ourselves, but that probably would not save us much money. The plot is mostly level, with minimal soil removal needed. A basement would be nice but probably not financially feasible. Since the land is already serviced, I assume there will be no significant additional ancillary costs (surveys, etc.).
I have estimated the following costs and would be interested to hear your opinions. As I said, I have no concrete offers yet (except for the land cost). The goal is just to roughly check the feasibility or financing.
At first glance, this seems high to me considering that we plan to do a significant part of the work ourselves. Turnkey semi-detached houses here start at around 650,000 €. Is my estimate too high? Where do you see potential for savings? Have I missed any important items?
In our area (greater Stuttgart), there is a 500 sqm (5,382 sq ft) plot of land for sale in a very good location. The price is 450,000 €. The plot is serviced and ready for immediate construction. Building on the plot alone is financially absolutely not feasible for us (both 32 years old, one child + one planned), so we would like to build a semi-detached house. My sister and brother-in-law with two children are also interested in building, and we can well imagine doing it together.
My brother-in-law is a civil and landscape construction contractor with his own company (excavators, trucks, etc.), and we think we are quite skilled with DIY work. We also have access to painters and heating technicians within the family, a friend who is an architect, and if needed access to trained or affordable helpers.
We can well imagine taking on at least the entire interior finishing ourselves (or subcontracting if necessary). To get the ball rolling, I would like to make a first rough cost estimate. The prefabricated house should come as a shell with exterior facade, windows, front door, staircase, roof, and connections included. This and other items (e.g., electrical work) would of course need to be finalized with the supplier. I would also likely subcontract the foundation slab to be safe. We might take on the earthworks ourselves, but that probably would not save us much money. The plot is mostly level, with minimal soil removal needed. A basement would be nice but probably not financially feasible. Since the land is already serviced, I assume there will be no significant additional ancillary costs (surveys, etc.).
I have estimated the following costs and would be interested to hear your opinions. As I said, I have no concrete offers yet (except for the land cost). The goal is just to roughly check the feasibility or financing.
- Half of the plot including ancillary costs: 250,000 €
- Prefabricated house as a shell (approx. 120-130 sqm (1,292-1,399 sq ft), 75 sqm (807 sq ft) footprint, 7x11 m (23x36 ft)): 250,000 €
- Material costs (flooring, landscaping, wall work, plumbing): 50,000 €
- Heating: 30,000 €
- Ancillary costs (construction electricity, foundation slab, utility connections): 30,000 €
- Total: 610,000 € plus any potential gratuities
At first glance, this seems high to me considering that we plan to do a significant part of the work ourselves. Turnkey semi-detached houses here start at around 650,000 €. Is my estimate too high? Where do you see potential for savings? Have I missed any important items?
Well, let’s start with the plot of land: Is there a soil report? What matters is not the green lawn, but the condition beneath the topsoil. In the Stuttgart metropolitan area: earthquake zone? This is a perfect point to generate addenda (sometimes completely unreasonable). A surveyor for the building permit / planning permission, etc., is also required.
If everything is "normal," I consider 250,000 € for a shell house to be excessive. Especially when I see that a manufacturer, who has already been mentioned in this forum, wants 257,000 € for a semi-detached house of that size, turnkey from the top of the foundation (even though foundation and some other costs come on top, it should then be capped at about 300,000 €). Whether you like that or not is another matter. The fact is, many providers make their living from sales, and the people staffing their show homes also have to be paid.
Of course, it depends on personal preferences—you can build luxury or mid-range. I wouldn’t build anything below KfW 40+ standard (photovoltaic systems are already mandatory in Baden-Württemberg, right?)
And so on and so forth.
If everything is "normal," I consider 250,000 € for a shell house to be excessive. Especially when I see that a manufacturer, who has already been mentioned in this forum, wants 257,000 € for a semi-detached house of that size, turnkey from the top of the foundation (even though foundation and some other costs come on top, it should then be capped at about 300,000 €). Whether you like that or not is another matter. The fact is, many providers make their living from sales, and the people staffing their show homes also have to be paid.
Of course, it depends on personal preferences—you can build luxury or mid-range. I wouldn’t build anything below KfW 40+ standard (photovoltaic systems are already mandatory in Baden-Württemberg, right?)
And so on and so forth.
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PurpleBee14 Apr 2025 10:59Rübe1 schrieb:
Well, let’s start with the plot: Is there a soil report? What matters is not the green grass, but what lies beneath the surface. Greater Stuttgart area: Earthquake zone? A perfect reason to generate addendums (sometimes completely absurd). A surveyor for the building permit / planning permission and so on is also required.
If everything is “normal,” I consider €250,000 for a shell house overpriced. Especially when I see that a manufacturer already discussed here in the forum wants €257,000 for a semi-detached house of this size, turnkey from top of foundation (although the foundation and some extras are additional, it should then be capped around €300,000). Whether you like that or not is another matter. The fact is, many providers make their money from sales, and the folks in their model homes also need to get paid.
It naturally depends on personal preferences—you can build luxury or mid-range. I wouldn’t build anything below KfW 40+ standard (photovoltaic obligations are already in place in Baden-Württemberg, aren’t they?)
and so on and so forth. This concerns a municipal new development area. I have the development plan, soil, noise, and environmental reports. No addendums are known to me. According to the listing, the plot is immediately buildable. Only a building permit / planning permission would need to be applied for.
According to the development plan, the roof must be greened, which, according to a guide, halves the number of required photovoltaic modules.
I have not yet given much thought to KfW standards and similar issues. We would have to discuss that with the architect.
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PurpleBee14 Apr 2025 11:00Musketier schrieb:
What does the floor area ratio say for the plot?
If the plot is not explicitly designated for a semi-detached house, it could get tight.The floor area ratio is 0.4, with 2 full floors allowed. The plot may only be developed with a single-family house; subdivision through condominium ownership (WEG) is permitted.
PurpleBee schrieb:
At first glance, this seems quite high to me, and some costs might still be missing.
PurpleBee schrieb:
Additional costs (construction electricity, foundation slab, utility connections): 30k € Additional construction costs can range from 30,000 up to 50,000. The foundation slab is not included in that. It is listed separately or included with the house. That can be between 20,000 and 30,000.
A soil survey for the new development area can serve as a rough guide, but a separate, project-specific soil report should definitely be commissioned to ensure the house’s warranty.
PurpleBee schrieb:
Floor area ratio is 0.4, 2 full stories. The plot may only be developed with a single-family house; subdivision under condominium ownership (strata title) is permitted. It is important to know whether two separate dwelling units can be built on the lot.
I would calculate it the other way around: what is financially feasible for you? Subtract the cost of the land from that, then deduct additional construction costs estimated at about 3,000€. What remains? What kind of house can you afford with that?
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