Cost estimate single-family house 145 sqm with basement

What does "a lot" mean?

How much it will really be then depends on the offers that come my way. I really enjoy doing hands-on work myself and also have some skilled craftsman friends. But of course, it has to be compatible with my job. I can scale back a bit at work + take vacation. But it strongly depends on the cost-benefit factor.

: I have also thought about that. But to make the basement a living unit, too much effort has to be made. Outside basement stairs, window areas, electrical systems, water connections, lifting system, heating, etc. The benefit of the subsidy is too small.

I have considered installing perimeter insulation around the basement, doesn’t that also have energetic advantages for the whole house? Otherwise, wouldn’t you have to insulate the basement ceiling?

So, many thanks for the participation! Now I have a rough scale to work with.

I have an updated plan. I have extended the staircase a bit and added a bay window after all. This is supposed to somewhat fix the cramped space conditions in front of the stairs. In the bedroom, an open, bright space will then also be created. The shallow pitched roof should simply be extended down further at this point (I don’t know the term for this, see attachment).

What I don’t like so far: Since the staircase is now longer and runs somewhat into the living room, the basement stairs probably have to go a bit "around the corner" into the utility room to avoid bumping one’s head. Unfortunately, I’m not familiar with stairs and their spatial requirements.

Does anything strike you as completely impossible or badly designed?

Regarding heating, I am also totally undecided. We don’t have a gas connection. And the thing with a tank in the garden is supposedly not really profitable. Oil heating somehow feels unsympathetic to me. With pellet heating the opinions on storage are extremely divided. I know people who complain about unreliability of the system (apparently with feeding the pellets). And with one person there is apparently a bit more moisture in the cellar than planned, so the pellets always absorb water. With brine heat pumps, I’m somehow scared of what would happen if the pipe leaked. Then you would have no heating until half the garden is dug up. And with air-water heat pumps, there are also two camps that either talk up or down the actual annual performance factor. But somehow this option is currently the most sympathetic to me. Or still pellets?

Questions, questions... :oops:

It would be extremely practical if you added a few measurements to your floor plan ;).

You must not only see the benefit of the subsidy! For our part, we hope to have the mother-in-law as a subtenant at some point, at the latest when she retires. If that is not the case, it can be rented out to outsiders and will also generate income.

And why do you want to mount the stairs outside? Usually, the space for the stairs is already "lost" in the ground floor.

The basement ceiling is insulated anyway; it probably has a minimal supporting effect but not necessarily.

We had our basement converted into a living basement.
It required additional insulation inside and outside, partition walls, electrical and plumbing + underfloor heating + 2 apartments + 3 larger windows + terrace door + entrance door about 50k extra. Additionally, painting and floor coverings are still to be added.

As a little tip
if you register it as a separate apartment, you can get the KFW funding again and declare it at the tax office.

Is it basically possible to apply for a KFW funding for the single-family house and at the same time one for a living basement? Basically then twice the maximum amount of 50,000 euros through KFW, so a total of 100,000 euros?

What are the requirements for the living basement, does it have to be separated from the single-family house?

Thanks, regards Michael

YES the basement must meet all requirements for Kfw, that means insulation etc.. additionally separate heating control and for us also an extra apartment.

the rooms are separated by the staircase and a basement room, as we are sure that it will eventually be rented out.