ᐅ Price difference between slab foundation and basement. Is it possible to estimate that?

Thank you for the responses! We will simply see what other construction companies say, plan, and see what comes out of it.

Renting an apartment nearby is our Plan B.
It needs to be a fully independent living unit.

In my opinion, it is questionable whether having a separate apartment (granny flat) is the right option for someone who is no longer independent.

If you decide to go ahead with it, this apartment must be suitable for care needs (sanitary facilities, door clearance widths, etc.; possibly a guest area for care staff).

To ensure that our mother/mother-in-law doesn’t have to live alone in the foreseeable future doesn’t mean she is already in need of care. She lives 150km (93 miles) away from us and has some minor health issues. Cleaning, shopping, cooking, etc., are becoming increasingly difficult for her... Additionally, due to an eye condition, driving is already borderline for her and will likely worsen to the point where she will no longer be able or allowed to drive. However, she lives in a very rural area where nothing works without a car! These are some of the reasons why she is moving in with us.

And if the need for care ever arises, we want to have her with us. With outpatient care services, people in need of care can almost always be looked after at home, especially if family members live nearby.

Doors and bathroom will be planned accordingly. The staircase to the granny flat could have been managed if necessary...

By the way, we have since had an appointment with another general contractor. He said that adding an extension is not really more expensive when you consider all the costs. So, it will probably be an extension.