We are also building in the south of Baden-Württemberg and have also gone quite deep into various timber frame prefabricated houses. I assume you will be building such a house? Since you require Kfw 40.
In advance: With your ideas, you will definitely not be able to stick to the budget. Because we are building similarly and have similar demands/requirements, but gradually became more and more aware of what one can/should do without, I would like to share our experience with you:
- As already mentioned by various people here in the forum: With your room requirements, you will not be happy with 140sqm and/or 130sqm with a cellar! You definitely need 150sqm to get everything you want. So it is important to clarify very precisely here: What do you really need and what can you afford? Good benchmarks with our builders were always around €2,000/sqm more or €2,000/sqm less.
---> Although we are building with a cellar and would never change that, if your budget is tight and you are not totally set on having a cellar, then better make the house 10sqm bigger and save yourself the approx. €50k extra cost of the cellar. Put together a floor plan from companies and look carefully at what you need and how big the rooms then are. The prefabricated house companies very much like to sell such "mini-houses" with 120-130sqm and claim that there is enough space everywhere, even for a family of four, etc. I always find this difficult and very individual... Do not let anyone talk you into this and think carefully about what you really need/want.
- Think about: smart home, blinds everywhere, all electrically controllable, cooling function of the air-water heat pump, room lighting, KfW 40 (can be useful with timber frame construction because of subsidies), cistern, bathtub (general bathroom layouts) --> All of this costs a lot, partly unnecessary money, and you will notice during further planning that most of these things can usually be left out. It reads to me as if you want everything but with a small budget. That definitely will not work.
- Have the preparation for photovoltaics done now, everything else will be too expensive if you do it later!
- Regarding the listed additional costs: The structural engineer costs SIGNIFICANTLY more than €1,000, soil surveys are also a bit more expensive, building permits (consider switching to the notification procedure here – costs not even half and may be possible), excavation with €11,000 is far too low. We have no hillside location and are currently at €30,000 - 35,000. This item can quickly rise significantly. The prefabricated house companies always calculated €10-15k for this with us... You need to be very, very careful here! You simply won’t manage with that nowadays! Otherwise, that should fit.
- Remember, if you want a large garage (prefabricated garage like Kemmler), you’re looking at €26,000 including foundations.
- For furniture/initial fittings, you’ll quickly be at €20,000, so be sure to watch this and calculate accordingly.
- You also need about €15,000 for the kitchen.
- For the outdoor area (you can do the garden later), you still have to budget around €15,000 if you do some of it yourself. Otherwise, the amount can quickly rise to €25,000!! Definitely keep this in mind!
---> Now, about the house:
Calculated on your wishes, without cutting anything here (about 140sqm with cellar), WITHOUT garage, WITHOUT additional construction costs, WITHOUT outdoor facilities and furniture, you are estimated at around €400,000. Since we are also building here in the south of Baden-Württemberg and already have several offers for similar projects, I know what I am talking about. You won’t get it cheaper with your expectations.
So I can tell you: Our plot cost exactly that much and we are currently at a total house and plot sum, including all additional costs, of around €620k-650k. I would estimate your total sum at around €580k-600k because we are not far from you regarding services/requirements etc. However, we do floors/painting work as well as the outdoor areas ourselves... So I can’t imagine you will get there with €500k-550k...
Also ABSOLUTELY note: The cost transparency of the prefabricated house providers we struggled with at the beginning was ZERO compared to the transparency of the regional solid builders. With prefabricated house suppliers, several services/costs will come at you afterwards that are not yet budgeted now. So very important: always stay realistic and maybe also look regionally at a company to have cost comparisons. The prefabricated house providers will tell you a lot, especially if you are still at the very beginning, all day long xD