Floor planning - Extend the house - What costs arise?

Hello dear house construction forum,

since 3 single-family houses are going to be built just around the corner where we currently rent, we got into conversation with the construction company.

They planned to put up 3 identical single-family houses.

Key data:

KFW 55 house in Bavaria (rural area)

approx. 8.3m x 10m + plot
no basement, 2 full floors, unfinished attic + garage 6m x 6m
insulated exterior walls
insulated floor slab
concrete ceiling on the 2nd floor
underfloor heating + heat pump
electrical and sanitary fully completed
also exterior fully plastered and painted
own contribution only flooring installation and painting + exterior landscaping
he would charge €240,000 for such a house.
I hope these key data are sufficient to answer my question.

However, since we need 3 children's rooms, such a house would be too small for us,

so the builder offered to extend the house by 2 meters (8.3m x 12m), so that upstairs instead of a storage room we gain a children's room + storage room and on the ground floor a pantry, and the kitchen becomes approx. 5m² larger.

For this property, he would charge €300,000.

Now to my question:

Is the surcharge justified?
€60,000 more for 2m house length?

Thank you already for your answers and efforts...

Best regards,

Andreas

2m extension means about 32 sqm more area on the ground floor/upper floor, let’s say 30 sqm more living space. Thus, the 60000 euros correspond to the often mentioned 2000 euros / sqm here. It does not seem completely unreasonable at least. One should check the offer 240000 again ... really including the [Grundstück] etc.? One should really check the scope of services carefully.

Where the 2k/sqm includes all the expensive building services, additional space is generally somewhat cheaper. On the other hand, it is not really decisive whether the surcharge for something you don't need is high or low – in the end, only the price in the bottom right counts. For example, if I want to buy a California, I don’t base it on the price of a Golf and what the difference is. Much more, I’m interested in how the comparison with the Marco Polo turns out.

New plans and a new structural analysis must be created. I do not find the 60,000 unreasonable.

In my opinion, it is somewhat plausible. In the original post, does House 8.3m x 10m include the plot of land or is it excluding the plot of land?

The property cannot be included for the price.