ᐅ Demolishing a prefabricated house from the 1960s and rebuilding

Hello everyone,

We are just starting to explore the topic of property acquisition and have the family opportunity to purchase a plot of land with a prefabricated house from the 1960s.

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

• Demolish the prefab house
• Keep the basement
• Build a new (prefabricated) house on the existing basement

Unfortunately, we currently have no knowledge of how best to approach and discuss such a project in advance. Are there people with experience who can recommend which types of companies to contact in order to evaluate the feasibility and costs of such a project? (Specific company recommendations for Hamburg are also welcome, if available.)

I’m not sure if this is relevant for a general question like this, but as mentioned above, it is a Hanse prefabricated house from the 1960s.

We would appreciate any advice.

Best regards from Hamburg

Hanse was and still is basically a fairly respectable manufacturer, until 1962 also based in Lübeck, so I assume a Hanse house in Hamburg dates from that period (?) – you should provide more details on this (and add photos to your comments). The 1960s were, however, a very dynamic decade in terms of construction technology (I would not call it "innovative") both for wood and masonry, so it was basically several decades in one. Even among the fairly reputable manufacturers, there was therefore a wide range of technical modernity. I assume that, on closer inspection, you will find not only the building fabric somewhat lacking, but also the simpler design: we are talking about the early days of today's standards, with bathrooms fully integrated into homes even for ordinary people; and also about the then-new trend of fitted kitchens. Both within a framework that today would be considered sparse. Furthermore, I suspect a footprint of seventy square meters or less, and accordingly a living space around or below one hundred square meters. The idea of continuing to use the basement is something I generally view positively – but this would also have to be evaluated based on the specific property. I would be less concerned about hazardous building materials: asbestos, yes, would need to be properly disposed of. But with wood preservatives and binders, I would be less worried – they mostly off-gas over time, and remaining concentrations are below those of brand-new alternatives. Such a house could certainly be gutted (removing internal wall paneling, etc.) – I just think, as I said, that one would probably not want that, because the layout would remain outdated. But: tell us more (and especially show more), then a more precise assessment is possible. My prediction is: I am most likely to recommend continuing to use the basement as part of a larger new build project as a base, but advise against keeping the house itself. But let's see. It’s best if you now add the completed questionnaire at the top of the floor plan section (pinned there) while your thread is still at the beginning, and include pictures, including an aerial photo and/or cadastral map.

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Hi 11ant,

thank you very much for your detailed response!

I’m not so much interested in discussing every last detail about the most sensible approach. We are quite certain that we would need to demolish everything above the basement to be able to realize our ideas and create a home that meets modern standards.

At this stage, we are looking for a feasibility assessment. That means:
a) how much would it cost to demolish up to the basement ceiling, including hazardous material disposal
b) how much would it cost to build something new on top (we are currently undecided whether to go for a prefabricated house or a solid construction. The budget will likely be the deciding factor)

To investigate this, we would like to know which companies are best to contact. Over the past few days, some personal contacts have suggested general contractors as a useful first point of contact. If you or others in the community have advice on this, it would be very helpful for us.

Best regards from Hamburg

NormanHH schrieb:

a) What is the cost of a demolition down to the basement ceiling, including hazardous material removal?

No one has a crystal ball here. It depends on various factors, from size to the building’s condition. There are quite a few companies, especially around Hamburg, that specialize in this. Just call and schedule an appointment. Getting a quote is often free of charge. Ehlert & Söhne, Wilko Wagner, TH Rückbau are just a few examples.

NormanHH schrieb:

b) What does it cost to build something new on top (currently still undecided between a prefabricated house or a solid house; money might be the deciding factor)?

You could put a tiny house on it, which might cost around 25,000€. Or are you thinking of a 3 million euro villa?
Unfortunately, this question can’t be answered precisely either. But to give you a rough estimate, expect around 2,600–2,800€ per square meter (10.7–11.6 sq ft) plus additional costs. For a simple single-family home, that would be about 400,000–500,000€.

NormanHH schrieb:

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

Simply get in touch with as many companies as possible and request catalogs. Visit the various model home parks around Hamburg to get a better idea of what you really want in the end. Once you find something suitable, arrange an appointment and have a conversation. They will tell you how much it will cost. And if it’s too expensive, just move on to the next provider.

11ant schrieb:

I generally see the idea of reusing the basement in a positive light – but this would have to be assessed for the specific property in question.

Agreed.

But especially with prefabricated houses, it’s unlikely to find a new floor plan that fits exactly on the top edge of the basement and has all the pipes positioned correctly.

Asbestos removal can get really expensive. To my knowledge, only certified companies are allowed to handle it.
It’s not something you can just do on the side.
So maybe it’s better to apply a sealing plaster instead?!

konibar schrieb:

But especially with prefab houses, it is unlikely to find a new floor plan that fits exactly on top of the existing basement wall and places all the pipes in the correct positions.

Thank you for pointing out two misconceptions (which some other readers might also have). Building on existing basements does not necessarily require such exact alignment—not even of the outline—and pipes can also be rerouted.

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