Building land with buried old cellar

Hello everyone,

in the meantime, we have reserved the plot mentioned in and are dealing more intensively with the construction of the 3-story building (but more about that in another thread). The housing company from which we would buy the plot had a multi-family house that stood there demolished. The cellar was also excavated and refilled. However, the walls (I assume the exterior, or all load-bearing?) were not part of this and probably remained. Buyers of other plots, whose demolition of the houses located there was also commissioned at that time, had already experienced the surprise that some construction debris was deposited there. Therefore, they advised us to have a soil survey (or percussion survey => what is that?) conducted (already during the current reservation phase). What should be considered in this? As far as I have read, a normal soil survey does not necessarily include a contaminated sites report. In this case, that would certainly also be sensible, right? This is generally recommended here, also because the arsenic and heavy metal content is often elevated due to the historical mining. So far, of course, we still have no (concrete) ideas about exactly where our house will stand (but quite precisely, since we are supposed to attach directly to the multi-family house on the neighboring plot). Does it make sense to clarify this first, in order to then carry out the drillings exactly on their outline, or does it ultimately not depend on the exact meter and we could already commission this? The next question concerns the neighboring plot. As far as I have read, in the case of a boundary development, the consent of the owner of the neighboring plot must be obtained. Is this also to be obtained in our case, even if the city (without a development plan) prescribes the closed building style?

Many thanks in advance.

The next question concerns the neighboring property. As far as I have read, when building on the boundary, you must obtain the consent of the owner of the neighboring property. Is this also required in our case, even if the city (without a development plan) mandates closed construction?

No. If the city mandates closed construction, the neighbor does not have to give separate consent, unless the closed construction would violate existing planning law. If your neighbor does not like your building application or the closed construction, then they have to sue against the building application and/or file an objection, i.e. take action themselves. The lawsuit would not be (directly) against your building application, but against the city's fundamental and justified determination as to why it requires closed construction here, because this determination applies not only to your building application but also to other building projects, in case you withdraw yours.

In principle and theoretically, it is of course possible that in 5 years the city concludes that closed construction is totally inappropriate there and mandates open construction – then you or other prospective builders would have to ask the neighbor whether building closed is allowed. However, this would be very odd considering the existing development. For me, that would immediately and drastically reduce the value of the property, so that I would either get the property thrown at me with the specification "open construction" or I would look for something else.

Best regards
Dirk Grafe

Hello everyone,

thank you very much for the response. Are there any further indications regarding the basic procedure concerning the soil investigation? So, to have the soil report created with estimated values even before purchasing the property, where the house will probably be located? And in addition to the pure soil report also a contaminated site analysis (which apparently is not always done).

Best regards

The soil survey should always be done BEFORE the purchase. If there really could be half a basement buried there with contaminants like asbestos and so on, the property can quickly turn from a bargain into a money pit. Such hazardous waste disposal is expensive. If you already know where you want (or have to) build, the soil survey can be more detailed and you will already get foundation recommendations. I would also recommend a contaminated site investigation. Better to invest 1000 € here and possibly withdraw from the contract than to have to live with the potential dangers afterwards.