ᐅ Comparison of Internal and External Insulation: Is External Insulation Significantly Better?

I am going to renovate a roughly 100-year-old four-sided farmstead. I love the old bricks and would like to keep them on the main house, which currently has no insulation at all. However, I am starting to have doubts. Based on the information I have gathered so far, exterior insulation is significantly more practical, easier, less expensive, and more durable than retrofitting interior insulation. Is this correct?
If so, after insulating, the facade would probably end up as a classic smooth finish (unless I add another, costly brick wall in front).

Best regards,
Karl

karl.jonas schrieb:

If I evaluate my information correctly so far, exterior insulation is significantly more cost-effective, easier, cheaper, and more durable than (retrofit) interior insulation. Is that correct?

Yes. However, it is not more durable—it is basically just attached insulation (whether ETICS or ventilated façade). The biggest advantage is that you insulate on the cold side and don’t have to deal with the issue of dew point shifts and moisture problems in the interior insulation.

This cannot be generalized. With interior insulation, there is now very good experience in historic buildings if it is carried out professionally. Especially in combination with clay plaster and wall heating, it has become a proven system.

@Myrna_Loy do you mean "historic" simply as old (like in my case), or more like "heritage protection requires the facade to be preserved, so significantly higher costs might have to be accepted"? Is a wall heating system something you would prefer to avoid due to the lost usable space? I assume it has to be about the same size as a floor heating system, right?

Old buildings. Not only historic monuments. In an uninsulated old building, it is also best not to place anything against the exterior walls to prevent mold. You lose some living space due to the approximately 8-10 cm (3-4 inches) wall thickness, but with low ceilings or narrow joists, you can avoid using underfloor heating. Additionally, only environmentally safe building materials are used instead of polystyrene, etc. The insulation lasts several decades or even longer indoors.

We are currently planning the renovation of our house from 1930.

We have now ruled out interior insulation (and mourn our beautiful brick facade). Interior insulation really needs to be done 100% correctly to work; otherwise, you risk condensation and mold inside the house. Most of the time, you only notice the mold late because you are not constantly checking your insulation.

Apart from that: there are specialists who can handle this. For us, it is out of the question to sacrifice living space just to preserve the exterior appearance and to accept the potential risks.