Prefabricated bungalow from the 80s shortly before purchase

Hello first of all I am new here in the forum and urgently need your advice. My girlfriend and I are in the process of buying and renovating a prefabricated bungalow from the 80s. The prefab house was built in 1976 by the company Streif Haus and has not been renovated so far. We really like the house and it is in a relatively well-maintained condition. What makes me a bit cautious are the thin interior as well as the thin exterior walls due to the insulation, etc. According to the report, no harmful substances were used in the house. Now my question is, is there anything to consider when buying an old prefab house? What would be advisable? I would also add pictures afterwards if desired. Thank you very much in advance. Best regards

The prefab house was built in 1976 by the company Streif Haus Haus [...] What makes me a bit suspicious are the thin interior as well as the thin exterior walls because of the insulation, etc.

"Prefab" house manufacturers from that time still exist by name, although mostly under different ownership. As far as the companies from that era have continued, construction details may still be well ascertainable. The exterior walls were typically filled with insulation material to their full thickness. Structurally, this resulted in total wall thicknesses that appear incredibly slim compared to masonry walls, but this is normal. In the early eighties, timber frame panel walls of, for example, 16 cm thickness were ahead of the then still common 30 cm thick masonry walls in terms of insulation by decades.

According to the expert report, no harmful substances were used in the house.

Modern problem building materials were never considered problematic at the time of their use. From a building biology perspective, that was the (pay attention to the pun) Stone Age back then. But in 45 years, a chipboard has off-gassed everything that could ever have caused concern and leaves less residual load than if you replaced it.

Be aware that a "prefab" house from 1976 is structurally unproblematic and retains value, but at best can only be brought up to a standard from twenty years ago: turning it into a smart home passive house would be unaffordable.

In the family, there is a Streif house somewhat younger, built in the early 80s. There were no problems regarding the substance. The floor plan and the technology do not correspond to today's standards. Nevertheless, it would be sufficient to go through with a can of paint and move in.

What does the energy certificate state? It is mandatory when selling and should be available to you.