Is it advisable to build a new house on an existing old basement?

Hello everyone,

I have a question that has been bothering me for a long time.

Many years ago, my family and I bought a plot of land with an old settlement house from the 50s. The settlement house has a 150 sqm extension facing the garden. The settlement house and the extension each have their own entrance but are also connected to each other. The extension has been extensively renovated and this is where we live. We only use the settlement house for the laundry room and hobby room. Both, the settlement house and the extension, are built as boundary developments.

The condition of the settlement house is not good. The roof will need to be replaced within 10 years at the latest. The facade has cracks. In the basement are the house connections for oil condensing boiler, oil tanks...

I am now considering whether I should demolish the settlement house, leave the basement standing, and build a new house on the old basement. The new house does not need any bathrooms, no entrance, no staircase (everything is available in the extension).

What would you do?

Best regards,

André

How is the basement constructed?
Can all the pipes be installed that way?
What would it cost to also tear out the old basement and build one?
(The most expensive part is often the digging.)

Otherwise, why not? If the structural engineering is okay, I might consider doing that too.
The question might still be which type of floor slab is installed.

I would then plan the construction so that you have the option later to create one or two additional apartments through a small renovation.
In case you don’t want to clean the whole house anymore when you’re older and want to have some extra money coming in, that would be practical.

When building on the boundary, the builder may need to plan for underpinning the neighbor's house, right? It can make sense to leave the basement in place, especially if the basement is still 'good' (i.e., dry)... Of course, all the debris from the demolition will fall into the basement... but it sounds like you can get the additional space fairly "cheaply" - the question is whether you even need it (with a 150 sqm extension...)