Detached house with a granny flat - is financing feasible?

Hello everyone,

I came across this forum through a Google search. I’ve already read one thing or another - that really makes me scared and nervous. Now I wanted to inquire first or ask for your opinion before I go to the bank or request the first financing offers.

About us:
We (Me 34 / Her 32 / Our child 4)
Monthly household net income: approx. €5,500 net (both tax class 4) (She currently works only 50%)
At the end of the month (after rent (€650) / living expenses / vacations etc.), we save an average of €2,200 per month.
(Don’t be surprised, we are currently relatively frugal (no big vacations etc.))

Plot
We bought a fully developed plot two years ago.
Plot approx. 1,100 m²
Plot price per sqm (as of 2024): ~€250
Back then we invested almost all of our equity and no loan was taken out.

About the construction project:
Bungalow with a granny flat approx. 250 sqm
A friend who is an architect drew us a plan for free, he estimates €600-650K
The granny flat will be permanently rented to relatives.
(We will certainly do some things ourselves, but I have not yet calculated that in)

Equity:
Equity approx. €40,000 - planned equity to be used max: €20,000

Monthly payment
In consultation with relatives (mother and her partner) - (regarding the rent costs etc., how we will internally settle that, I don’t want to go into detail ;),
we plan to repay approx. €3,800 monthly.

If any information is missing to better assess the situation - feel free to ask anytime.

How do you see the framework conditions?
Thanks for your input

In my opinion, the construction costs for a bungalow are set far too low. 3000 €/sqm will more likely be the minimum. With the additional costs, you will probably end up at ~850,000. If you cannot contribute a lot (!) of your own work, you’d better forget about it quickly.

Don't be surprised, we are currently relatively frugal (no big vacations, etc.

Relatively frugal?
€2,650 living expenses (does the child benefit come on top of that or is it already included in the €5,500) for three people is not relatively frugal. But that's off topic

Bungalow with granny flat approx. 250 sqm
A friend who is an architect drew us a plan for free, he estimates €600-650K

Better plan for €850K, I agree with . Or your architect calculated net.

we planned to repay about €3800 per month.

Since you asked the question "Is financing feasible," I ask for a complete question including all necessary facts.
I do financing myself and with the information you provided, I send you home first to give me reasonable and complete numbers.

All right. Thanks in advance. I already had my doubts about the project. What surprises me is that both of you are expecting 200K more - I already considered that realistic. Reference - bungalows that were built nearby in the last two years, the 3000€ / sqm would also fit with that. But thanks anyway - maybe we should just plan a bit smaller.

What surprises me is that you both are calculating with 200K more

Experience from the job - my clients do not perform any work themselves, but always build 100% with craftsmen (professional clients). There, the 3,000€/sqm as pure construction costs are no longer feasible, but higher.

With a granny flat, some expensive things are incurred twice, so I also consider the 650,000.-- clearly too little.