Tear down a prefabricated house from the 60s and rebuild it

Hello everyone,

we are just starting fresh with the topic of property acquisition and have the family opportunity to purchase a plot of land including a prefabricated house from the 60s.

Unfortunately, the prefabricated house is contaminated with hazardous materials such as asbestos due to the construction methods used at that time. For this reason, and because the prefabricated construction methods back then are probably not as good as today's, we are currently considering the following option:

[*]Tear down the prefabricated house
[*]Leave the basement standing
[*]Build a new (prefabricated) house on the basement

Unfortunately, we currently lack any knowledge on how best to approach and discuss such a project in advance.
Are there people with experience who can recommend companies to contact with this kind of request to examine the feasibility and costs of such a project? (Preferably specific company suggestions for Hamburg, if available)

I don't know if this is important for such a rough question, but it is a Hanse Fertighaus, as mentioned above from the 60s.

We would be grateful for any advice.

Best regards from Hamburg

Hanse was and is basically a fairly decent manufacturer, until 1962 also based in Lübeck, so I assume a Hanse Haus in Hamburg dates from that time (?) - you should tell us more about this (and add photos to your words). The 1960s, however, were a very evolutionarily active ("innovative" I would not want to say) decade in construction technology (equally in wood and stone), so quasi several decades in one. Even among the fairly decent manufacturers there was therefore a wide range of technical modernity. I assume that upon closer inspection of the property, it will be less the building fabric that is barely satisfactory for you, but rather the simpler design: we are talking here about the infancy of today’s standard, having bathrooms fully integrated into the apartments even in the homes of ordinary people; and also about the still new trend of fitted kitchens. Both in a framework that is now considered sparse. Furthermore, I assume a ground area of seventy or fewer square meters, and accordingly a living area around or below one hundred square meters. The idea of continuing to use the basement, I generally see positively - but this too would have to be assessed on the specific property. On the other hand, I would worry little about construction pollutants: asbestos, yes, would have to be properly disposed of. But I would be little concerned about wood preservatives and binders: these will mostly have outgassed, and the remaining concentration will be below the values of brand-new alternatives. Such a house would certainly be gutted (removing wall cladding from the inside, etc.) - I just think, as said, that you will not want to, because you would end up with an unmodern house in terms of layout. But: tell (and above all show) more, then it can be assessed more precisely. My prognosis is: I will most likely assess the basement as worth keeping, using it as the partial basement of a larger new building as the basis, and rather recommend rejecting the house itself. But let us wait and see. Best now, while your thread is still at the beginning, you fill out the questionnaire pinned at the top of the floor plan section, and add pictures including an aerial photo and/or a cadastral excerpt.

Hi 11ant,

thank you very much for your very detailed answer!

For me, it's not so much about discussing in the last detail what the probably most sensible way is. We are quite sure that we would have to demolish everything above the basement in order to implement our ideas and to get a home that meets today's standards.

In the next step, it's about a "feasibility check". That means,
a) what does it cost to demolish down to the basement ceiling including hazardous material disposal
b) what does it cost to build something new on top (currently still quite undecided whether a prefabricated house or a solid house. Money may be decisive here)

To check this, we would like to know which companies are best to contact. In the last few days, through personal contacts, general contractors have occasionally been mentioned as a sensible first point of contact. If you or others in the community have advice on this, it would be super helpful for us.

Best regards from Hamburg

a) what does a demolition down to the basement ceiling including hazardous waste disposal cost

No one has a crystal ball here. It depends on various factors from size to the building structure. There are quite a few companies especially in Hamburg that specialize in this. Call and make an appointment. Often up to the offer this is even free. Ehlert & Söhne, Wilko Wagner, TH Rückbau just to name a few.

b) what does it cost to build something new on top (currently still quite undecided whether prefabricated house or solid house. Here the money may be decisive)

You can put a TinyHouse on it. That then costs maybe 25k. Or should it be the 3 million villa after all? Unfortunately, this question also cannot be answered. But to give you a rough price, calculate about 2600-2800€ per sqm + additional costs. For a simple single-family house that would be about 400k-500k.

To check this, we would like to know which companies are best to contact.

Simply contact all companies and get catalogs. Visit the various model house parks around Hamburg to even know what you actually want in the end. When you find something suitable, make an appointment and have a conversation. They will then tell you how expensive it will be. And if it is too expensive, then just go to the next provider.

The idea of reusing the basement is basically positive in my view - but this would also have to be assessed on the specific property.

Agreed.

But especially with prefabricated houses, it is unlikely to find a new floor plan that fits perfectly on the basement upper edge and provides all pipes in the right place.

Asbestos disposal can get really expensive. As far as I know, only certified companies are allowed to do it.
Just doing it casually on the side is not an option.
Maybe it's better to apply a sealing plaster after all?!

But especially with prefabricated houses, it is unlikely to find a new floor plan that fits exactly on the basement top edge and provides all pipes in the appropriate place.

Thank you for your input on two misconceptions (which are probably also made by some other readers). Building on existing basements does not at all require such congruences – not even in terms of the outlines, and pipes can also be "shifted".