Here is my problem: I have an old house - nearly 100 years old - that I need to insulate but I have a few problems and concerns I need to deal with. The walls are essentially stone and an old kind on solid cement block.
I've been looking into the insulation solutions available in my market and it is basically a matter of gluing thick boards of styrofoam-like material to the walls.
On the outwalls this is not feaseable as the house faces a road with no sidewalk, so I'd be encroaching onto the road. Inside, adding 5cm of insulation would make small rooms smaller to the point some would be, for all practical purposes, rendered into generous pantries.
Because I live in a somewhat rural area, mice and rodents are a concern, so adding materials they can chew through makes no sense. It would be like supplying an easy to move through medium to run the entire house. I have seen houses and buildings with this kind of insulation chewed into, the moment the smallest of pieces of the hard plaster gets cracked, which is very easy. The added fire hazard is a concern as well, I'll admit.
I've already seen cork insulation but the base color is always brown and does not deal well with being painted on.
What other options may I look into? I'm in southern Europe but in an area with harsh winters.
With old masonry wall construction, you need to be very careful about how you retrofit insulation to the walls. Insulating the interior makes it very likely that you'll have moisture-related degradation of the stone and grout making up the wall, as you're cutting off drying potential from the interior side of the wall. If it's possible, insulating the exterior is your best option, otherwise you'll need to be very conscious about selecting vapor-open insulation and finishes on the interior side, which will limit your options considerably. This article from Building Science Corporation goes over some of the details, and offers some options for interior-side retrofits that might not cause the wall to fail down the road.