Construction project risk due to lack of equity

Hello to the experts in this round,
I find myself in the following dilemma and need your objective assessment:
Due to extremely unfavorable circumstances from the extended family circle, there was a long-lasting significant imbalance.
Through thriftiness and discipline, we are now almost out of the valley, i.e. the last remaining 35K of 300K will be repaid early on 15.10.2019 and thus have no obligations left, no car leasing or anything similar.
The credit report is clean and strictly monitored, it is practically my quarterly motivation booster, let's see if we can make it to 99%, currently at 98.48%.
We have long wished for a house and urgently want to get out of Frankfurt, keeping in mind that the conditions in kindergartens and schools are catastrophic, there are certainly exceptions in well-to-do districts, but then one does not even have to think about a house anymore.
We have currently found something suitable, it is about a RHM, 30 minutes driving time from the workplace and a completely relaxed area, some may find it boring there, for us it is a dream.
The whole thing is currently in the marketing phase, the semi-detached house was apparently gone within a week, the rest sells like hotcakes, in total it is about 50 little houses.
To keep my chance, I made a reservation after multiple viewings and conversations with residents of the 1st construction phase, paying 3K, which will be credited upon conclusion of the contract, but if you withdraw, 500 € are deducted as administrative costs. To preserve the chance, the 500 € were worth it to me, everything seems to fit for us at first glance.
The notarized contracts are scheduled for winter 2019 according to the developer, the construction time should be between 12 and 15 months, so that occupancy in late 2020, early 2021 is possible, I assume with a buffer of +- 2-3 months, depending on how well everything goes etc.
It is a classic terraced middle house with 5 rooms, 141 sqm and +- 130-140 sqm plot, all according to WEG as a KFW 55 house with utilization of the KFW loans regarding financing.

Position	Amount	Remarks
House price	368,000.00 €
House connection electricity, water, sewer	5,000.00 €
Carport	7,500.00 €
Sum	380,500.00 €
Property transfer tax 6%	22,830.00 €	Notarization planned for winter 2019, according to developer
Notary costs 1.5 %	5,708.00 €	Notarization planned for winter 2019, according to developer
Land registry entry	1,903.00 €	Notarization planned for winter 2019, according to developer
Broker commission	- €
Total financing requirement	410,941.00 €	excl. home furnishings, painting and flooring work and materials, as well as garden
Own contribution
Garden	3,000.00 €	plus materials, not included
Floor coverings	5,000.00 €	plus materials, not included
Wallpapering/painting	7,000.00 €	plus materials, not included
Equity
Down payment/reservation	- 3,000.00 €	Will be credited against the land price
Building savings contract	- 2,300.00 €	Terminate existing contract
Cash funds	- 5,000.00 €	Can possibly be increased to 10,000.00 €.

This is somehow a pretty extensive post, I hope someone reads it

Our income situation compared side by side is also significant, therefore presented in a list with multiple sections and calculated very conservatively, without bonuses, tax refunds, solidarity surcharge removal etc.

Situation	Husband	Wife	Child 1	Child 2
until 11/2019	Sole earner	Housewife	Adult, in training	2 years
Net income	5,950.00 €	0	left out
Child benefit	402.00 €
Fixed costs, incl. rent (warm 830 €, cold 620 €) incl. 300 € additional buffer living expenses and miscellaneous	- 2,500.00 €
Loan	- 1,337.00 €
Available net income	2,515.00 €
Situation	Husband	Wife	Child 1	Child 2
from 12/2019	Sole earner	Housewife	Adult, in training	2 years
Net income	5,950.00 €
Child benefit	402.00 €
Fixed costs, incl. rent (warm 830 €, cold 620 €) incl. 300 € additional buffer living expenses and miscellaneous	- 2,500.00 €
Available net income	3,852.00 €
Situation	Husband	Wife	Child 1	Child 2
from 09/2020		Part-time elderly care	Adult, in training	3 years
Net income	5,950.00 €	800.00 €	left out	Kindergarten
Child benefit	402.00 €		Child benefit ends in 2021
Fixed costs, incl. rent (warm 830 €, cold 620 €) incl. 300 € additional buffer living expenses and miscellaneous	- 2,500.00 €
Available net income	4,652.00 €
Situation	Husband	Wife	Child 1	Child 2
from 01/2021		Part-time elderly care	Adult, in training	3 years
Net income	5,950.00 €	800.00 €	left out	Kindergarten
Child benefit	201.00 €		Child benefit ends in 2021
Fixed costs, including 300 € additional buffer living expenses and miscellaneous	- 1,700.00 €
House fees and other incidental costs, administration etc. WEG	- 500.00 €
Available net income	4,751.00 €
Reserve for annual special repayment per month	- 1,000.00 €
House financing maximal	- 2,000.00 €
Available net income	1,751.00 €

My concern is to plan for bad times, i.e. if I unexpectedly become unemployed, then the unemployment benefit I (ALG1) will still cover the financing and a few extras + my wife's income, with which one could survive a certain dry spell if it gets tight.
We want to be done with the whole project in 15-18 years, possibly KFW 3 years interest-only and pay the other loan higher depending on the interest rate etc.
I know it would be better in every respect with saved equity, but at the moment the problem is rather that building costs and the availability of properties are actually getting worse and I have had to watch for the last 3 years how the whole thing continues to climb.
After the repayment of the last obligation in October, I am for the first time even remotely able to get financing. A preliminary inquiry with a Postbank consultant had already signaled green light, but with a corresponding interest surcharge.
I will of course treat the whole thing as a tender so that there are comparisons from different sources, and we have also already decided that professional help will definitely be involved for contracts etc., I think the money is well invested and I have no idea, not my field and you cannot just casually read up on it.
So, now I have really laid my cards on the table, I hope this will not bite me in the behind
For all those who have made it this far, thank you for still having the patience and curiosity to read such treatises. I look forward to objective and honest feedback, of course, there is always a lot also between the lines regarding development etc., but that would go beyond the scope, haha.

Best regards
Family Storch

I have read the long post. Please forgive me if I now give a short answer. I find your income sufficient for this amount. It may be unevenly distributed, but compared to families who are still planning to have children, it is much more calculable and is more likely to increase than to have financial dry spells. What does not add up at first glance is being done with a monthly rate of 1337 within 15-18 years. For a €400,000 full financing, I roughly come to 28 years until full repayment. A €1000 special repayment does not significantly shorten that.

I have read the long post. Please forgive me if I now give a short answer. I find your income sufficient for this amount. It may be unevenly distributed, but compared to families who are still planning children, it is much more predictable and is more likely to increase than to have financial dry spells. What does not add up at first glance is to be done within 15-18 years with a monthly rate of 1337. For a €400,000 full financing, I roughly come to 28 years until full repayment. €1000 special repayments do not shorten that significantly.

Hello Tassimat, thanks for your perseverance The 1337 is the current ongoing obligation until October this year, it will then fall away as a burden.

Oh, misread.
Is there already a more concrete financing concept?

Regarding your question about the risk: I understand you as being afraid that you might not be able to service the loan anymore. That usually only happens with general life risks such as unemployment, disability, separation, death, or similar. Two of those things can be covered with insurance. Unemployment can be bridged for a short time. No idea what you do and how easy it would be for you to find something similar new at a certain age, but if things go really badly, then both of you will have to work full-time in bad jobs. So how to insure against unemployment? You can basically only do it the way you plan: low monthly repayment, high special repayments. Or agree on a flexible repayment rate change.

Anyway, if the money stops flowing, then selling naturally remains the last resort. The risk with full financing is especially high in the early years, when the sale cannot cover the loan plus the prepayment penalty.

I have read here at the beginning "division according to WEG". Appropriate service charge payments still need to be taken into account here....

I have also read through it, but I am not an expert in financing. I always see the risk when the hidden costs are not recognized in the house offer. Can the offer be accessed on IS24 or Immonet? If so, please provide the ID. Then one can take a look. Or do you already have the construction service description? A classic example is the electrical package, which offers the number of sockets from the 1970s. Then upgrades are needed, which the builder charges dearly for. Including floor plan changes, controlled residential ventilation, or shutters, five-figure amounts in the medium range add up.