Internal and external insulation, how should the balcony be insulated?

No. The interior insulation does not have to be removed. Although double-sided insulation is generally not optimal, the 2 cm of Styrofoam on the inside is so minimal that it is absolutely irrelevant. The exterior insulation just needs to be sufficiently thick (dew point calculation). But due to the applicable Energy Saving Ordinance, you are in any case required to install sufficiently thick insulation. In theory, the interior insulation (without exterior insulation) should have caused more damage, but there are plenty of studies showing that while the interior insulation doesn’t help much, due to the low insulation thickness it also does not cause any damage. Regarding the balcony, it would probably also need to be insulated, otherwise you would have a very cold living space ceiling, which would be very susceptible to mold growth. Best regards

In general, an internal insulation of 1 to 2 cm is physically unproblematic, but that does not mean that it cannot lead to problems. It also depends on many factors. Since you do not know how the indoor climate was with the previous owners. Because permanently high indoor air humidity can also cause mold growth with such internal insulation ([vermtl. GK mit 2 cm Styroporauflage]), since no vapor barrier exists. In the worst case, the dew point may have been shifted too close to the inside of the exterior wall by the insulation. If it is not too much work, you should make sure and open the wall in several places of the exterior wall (preferably in the room corners of the exterior wall and in the lower meter area as well as the base area) by cutting out 10x10 cm sections, which you can glue back in with adhesive binder if there is a negative finding.

Otherwise, I agree with S.D. regarding remaining with the installation of a sufficiently dimensioned exterior wall insulation.

Hopegro

Hello S.D. and Hopegro Thank you for the quick info. That really takes a weight off my mind. I had already, since I’m no expert, feared based on my gut feeling that the interior insulation would have to be removed. That would be a few hours of work just to take down about 200 sqm of exterior wall. Then there would also be the costs and time for re-paneling .... Of course I will follow the tip with the test holes. I want to see what is behind the insulation. Thanks for the tips .... more questions will certainly follow Have a nice day to you all Powerracer