ᐅ Reduce the basement size because you plan to add external insulation?

Hello everyone

We have the following question:

We are planning to insulate our basement ourselves together with our neighbor, adding 10cm (4 inches) of Styrodur insulation from the outside.

The basement is currently designed to align flush at the top with the insulated wall of the ground floor and upper floor.

Our construction company now suggests making the basement 10cm (4 inches) smaller so that, with the additional basement insulation, the alignment is maintained and no water can get between the house and the insulation.

Does anyone here think this makes sense? We have heard so many different opinions on this and are now quite uncertain.

Thank you in advance.

Best regards

Hello, I believe this is not only practical but also a commonly used method to have the masonry extend, for example, over the reinforced concrete basement. I would even recommend setting back the first two layers.
Best regards, Ronny