Prefabricated house built in 1970 - Is renovation worthwhile? - Experiences?

Hello everyone,

my partner and I have been looking for a house to live in for a long time, and now we have found one that is perfect in terms of location/layout etc., but it is a prefabricated bungalow with a flat roof built in 1972.

Here are the details briefly:
Plot 950 sqm, great location slight south slope edge of town, undevelopable, not visible from outside
130 sqm, fully basemented, basement made of 30cm concrete bricks,
basement ceiling 20cm concrete with a
flat roof bungalow built in 1972 using prefabrication with good room layout and orientation on the plot
oil heating built in 2000
final energy demand according to certificate 260 kwh

The price is cheap, about 2/3 to 3/4 of the price is roughly the value of the land, we can pay 100% in equity and would even have over €100,000 equity left for renovation.

Since the year of construction, nothing significant has been renewed, but I would describe the condition as well maintained. We have not noticed any obvious major damages, basement dry, roof appears to be tight, facade still looks good.

The manufacturer of the house no longer exists but I have all the construction documents in great detail, about 50 pages. The manufacturer was two towns away from the building location and apparently did not build many houses, at least Google finds no results.

I would like to buy the house, my girlfriend, a trained chemist, is still skeptical, especially because of the pollutants. I would now need an assessment of the building quality and pollutant load. We want to avoid a complete renovation as far as possible. I am of the opinion that compared to other prefabricated houses from that year, the wall structure is of higher quality and fewer pollutants were used. I could not find any asbestos-containing materials in the documents. Also no glass wool as insulation, which tends to sag. The only thing is that all the wood, as was common at the time, seems to be heavily impregnated with wood preservatives.

The wall structure with 220-240 mm thickness is described as follows from inside to outside:
12.5 mm drywall boards
Nepa vapor barrier in kitchen/bath
100-120 mm load-bearing wooden construction made of healthy wood triple effectively impregnated
50 mm building felt
15 mm rigid foam
2 mm Perkalor Diplex
50 mm Heraklith
5 mm expanded metal
35 mm exterior plaster

The roof is designed as a 2-layer cold roof construction, the build-up from bottom to top is as follows:
9.5 mm drywall boards
subsheathing of impregnated boards
vapor barrier in kitchen/bath
220 mm load-bearing wooden construction made of healthy wood triple effectively impregnated
its cavities insulated with building felt double layer of insulation mats
planed tongue-and-groove boarding
EPDM foil
5 cm gravel fill

What do you generally think of the offer and the construction quality of the walls and the roof? Is it conceivable to leave the house standing and only replace the windows, roof EPDM foil (possibly additional insulation), and heating in the next few years but otherwise, apart from the usual painting/floor coverings, not to carry out any major renovations, especially no complete renovation?
The electrical installation should run in empty conduits, I think, so easy to replace if necessary. The water pipes run all vertically through the basement ceiling and should also be very easy to replace.

Am I just talking the house up or can it really be bought like this?

Many thanks for your help.

A complete renovation of a prefabricated house is not possible. Bringing it up to today's standards will be very expensive. The flat roof has probably already been replaced once. Was EPDM already available back then? Why change the heating system? Why water pipes? Is the electrical system reasonably adequate? If one can live with the limitations, as presumably millions of Germans do, it is a good opportunity for a lot of space in a developed residential area.

I would not buy without testing for pollutants. Of course, it depends on how sensitive one is to the issue, but prefab houses from that period were usually heavily contaminated, which besides the obvious health effects can also lead to unpleasant odors (chloranisoles). It is best to have a professional inspect it if the property is to be purchased. Why should the electrical wiring run through empty conduits?

A complete renovation of a prefab house is not possible

Why should that not be possible?

We want to avoid a complete renovation of the house as much as possible.

Why not?

I am of the opinion that, compared to other prefab houses from the same year of construction, the wall structure in this house is of higher quality.

You hardly have any insulation. That’s actually something you want to improve. Possibly install underfloor heating, renew and upgrade the electrical system to modern standards, renovate everything in a contemporary way.

Still skeptical, especially because of the pollutants.

Many say that the pollutants and odors have long since dissipated.
But that can also be improved.
You buy the house without financing and still have €100,000 left. Just for maintaining the value after 40 years, some work should be done. You are probably financially capable of comfortably repaying a loan of €200,000. Once you live in it, you won’t have access to certain things anymore. The construction dust should not be underestimated either.

Is there a prospectus online on a portal?

Of course, it makes sense.

The location fits, the property fits, the basement fits, and the house as well as the price also fit.

I’m also not a fan of prefab houses. You could completely gut the house except for the load-bearing wooden structure.
Insulation and cladding renewed, electrical, plumbing, etc. as well. Maybe even install underfloor heating with a heat pump.
The roof could also be re-covered. Does it pay off? It will definitely be cheaper than a new build.

But then you would have an almost new house on a perfect plot, even with a basement. Just what you save in planning costs, etc.
Everything is developed, and a basement today is almost priceless.