New single-family house in southern Germany

Hello everyone,
after I basically barged into the basement thread, I want to use this as an introduction and idea-collecting thread. Some things might seem a bit chaotic, but that will surely clear up.
We are expecting our first child in February. Since 2 rooms are a bit too little in the long run, we need something bigger. The housing market here in Konstanz is rightly notorious, so we didn’t search here for long but immediately focused on somewhat more distant areas (thanks to Corona home office). At first, we searched more on the existing market, but given the junk being sold, we unexpectedly ended up deciding to build and were actually lucky to get a spot in a new development area around Stockach-Pfullendorf. The area has been developed since this week and will probably be buildable from summer.

Here are some key data:
- he/I am 33, working in the software industry, work location Konstanz, come from the countryside
- she is 41 and a teacher in the Hegau, comes from a city that doesn’t exist
- one child on the way soon, no more planned and unlikely due to her age
- currently 2.5 rooms about 65sqm in a beautiful residential block…
- basically we don’t need anything overly fancy, no elaborate home automation, no luxury pad with marble and whatnot, just something solid and nice. We are not building to fulfill a long dream but to avoid renovating an old house for half a million. Textured wallpaper and laminate flooring would be okay for us if the quality is right
- accordingly, we see fewer problems taking a “standard” floor plan from a prefab builder or model house
- but since we’re already building, it should make sense energy-wise and we don’t want to build according to concepts that are politically targeted for abolition
- own work only to a limited extent as we are neither specialists nor have the right contacts. Also, the new house is a bit further away, so quickly doing something in the evening is not realistic. Painting for a weekend before moving in is no problem, also after moving in carport, terrace, and garden are no problem
- building partner must be reliable

Plot and finances
- plot about 700sqm at 98€ -> 70K, relatively rectangular
- 120K equity (a little reserve still available)
- financing and ownership entirely under my name (since unmarried and no joint assets intended)
- targeted total budget about 500K
- targeted rate 1,500€
- accordingly repayment only with rate in 25 years; medium-term a few special repayments are planned so the goal is more like 20 years

Budget estimate:
- plot 70K
- incidental plot costs 5K
- additional construction costs 60K
- basement 50K
- kitchen 10K
- driveway, carport, terrace in own work 15K
----------------
210K
Leaves about 290K in the budget for the house, which is certainly tight for the planned one
Budget would need to be adjusted for a buffer

So far we have roughly the following wish list
- not excessively large, more like 120-130sqm
- efficient, modern house
- photovoltaic (possibly with storage)
- underfloor heating with heat pump
- study for me on the ground floor (only makes sense to move that far out if I mainly work from home)
- bedroom upstairs, 1 study for her that also serves as guest room and reserve child’s room
- large living kitchen
- basement
- cistern
- carport for 2 cars and 1 trailer

First contact on building was through an ad from the local Town & Country partner. Consultant is likeable, show house in Geisingen also looks quite nice but somehow it all seems a bit too conservative to me. Building according to Energy Saving Ordinance 16, standard gas heating, sure it can be upgraded but whether heat pump still makes so much sense with the Energy Saving Ordinance... I don’t know. And if a show house has cracks in the plaster in some places, that’s not exactly helpful either. But the base price is cheaper. Current status: 2 meetings, visited show house, building specification not yet requested

Then came a bit on the prefab house topic. Most offer KfW55 standard, which is more like what we want and would also be a good basis to go to KfW40+ since a photovoltaic system is already set (albeit probably only with storage preparation). Visit to the park in Villingen-Schwenningen. Talked a bit with Schwabenhaus, impression that the consultant tries to minimize costs and also strongly wants to sell a brine-water heat pump with probe drilling. The upgrade stage of these promotional houses rather suggests even higher costs. Visit to Heldhaus, actually quite liked it but cost sketch blows the budget by about 100K.

Today appointment at Schwörerhaus. Floor plan for one of their promotional houses fits quite well, basement and KfW40+ seems more problematic in combination. Otherwise actually quite a good impression, even the briefly glanced building specification does not suggest a bad living experience in the house. Let’s see what comes out in the first offer. I don’t have the feeling you can do much wrong there.
Next week one more appointment at Weberhaus. We picked a floor plan that we like quite a bit. Price is initially the most expensive, but the price examples already include 40+ and home automation.

Goal would be to narrow down the number of companies we continue with to a maximum of 2 by Christmas and then decide on a building partner in the new year. In spring there should be time for the baby and not only for planning the house.

I’ve already posted a few thoughts about the basement or basement replacement room. The insulation costs apparently completely consume the additional funding for the basement, so the photovoltaic storage then goes at our own expense again. One thought on the way back from the appointment was whether it makes sense to build the house as KfW55 first without the additional insulation. Regarding heating costs, the difference is rather small. From the manufacturer then only install the empty conduit for the photovoltaic and with storage preparation. In a few years add a storage when they become cheaper. That would probably also fit the planned budget better than a 40+

So far these are my considerations. Did I forget anything important?

after I basically barged into the basement thread, I want to use this as an introduction and idea collection thread.

This is a rather moderately good idea insofar as the wind directions in the categories floor plan and financing are quite different here, so as a layperson you have to be able to quickly duck into the trench under the crossfire of well-meaning and know-it-alls. So better discuss finances and technical/design house construction in separate threads – incidentally, the financing section is largely 11ant-free ;-) If there is already a specific plot of land, it should also be presented in more detail, preferably including its zoning plan and topographical framework conditions. Be clear about what standard you want – and best weed out early those providers who want to convince you that things that are not important to you are practically cost-neutral thanks to funding programs. For the average consumer-patient, there is the Energy Saving Ordinance – anything beyond that addresses the clientele "avant-garde." Simply put: if you don’t shop several times a month at the organic store, leave KfW40 or even passive houses to other home builders. Or as says, simple rugged reliable. Don’t reinvent the wheel: every deviation from the standard costs (not just money), so pick your (manageable handful of) fronts on which you want to fight, e.g. "eco-bio-sustainable" OR "smart". Linking several fronts with AND requires above-average financial power and willingness to learn about technology. Today, you can do a PhD on different extraction hood concepts, but you don’t have to ;-)

When it comes to financing, I’m now less worried. The budget is roughly set and there will be a bank to finance it on reasonable terms. Now it’s about aligning the wishes with the budget. There should be no budget overrun before construction even begins ;) That’s why I’m also considering possibly not going for KfW40+ even though I find the idea with the battery exciting. But in the end, it’s more of a nice-to-have and not a must since it can be retrofitted quite reasonably anyway. The 12TE difference in subsidies is just not enough to cover the gap between the set budget and what is needed. I’ll present the plot this evening, unfortunately we don’t have many details yet, only a scan of the graphical development plan showing the available plots, I also took a few photos during the viewing. But since the development is just starting, it’s naturally difficult to determine the exact boundaries and estimate the slope.

I’m now less worried about the financing.

I’m not worried about your financing either, but about your mental and emotional health if you get told in the same thread into the same ear what to make of your plans – simply because the composition of the discussion community here in the foundation area is completely different from the financing area. In one area your vest has to be bulletproof, and in the other stab-proof ;-)
So you basically have to alternately hold one of your ears shut, otherwise you’ll go crazy if at the same time you’re told in one ear: “turn your staircase out of the dirt area” and in the other: “my gross-net calculator says your calculation doesn’t add up.”

Since a custom-designed house probably isn't worthwhile for us, walls and stairs are fixed anyway and only changeable through a completely different floor plan. Accordingly, such discussions should hopefully be avoided here. But I think I will change that again this evening.

Basement for 50k is very ambitious 290k for 120-130 sqm should be feasible. Would drop KFW40+. Your house is not big. Make a precise room plan. Not kitchen, sleeping, bathroom, but kitchen with peninsula 4m continuous work surface bedroom with 2.20 m long bed (because you are a giant after all), 4m wardrobe + 1m for towels 6m bookshelf, XXL sofa etc. You have no flexibility with the area. Large area compensates for planning errors. For every floor plan you like, draw in your furniture. That's how you find your floor plan out of the huge pile. In addition, the development plan means not every house is allowed on every plot