Build a small multi-family house in Cologne

Hello everyone, I am new here in the forum and warmly greet the community. So I will start from the beginning. I bought a mid-terrace house in 51105 Cologne, built around 1900, with the dimensions 6.15m wide and 11.50m deep, and the plot 6.15m wide and 22m deep. 2 floors plus an attic, unfortunately the attic is only 2 meters high. Since it is a very old house and almost nothing has been done over the years, it looks accordingly. Originally, I wanted to have it completely refurbished, from top to bottom..!! However, the carpenter who wanted to build me a new roof structure said that a building permit etc. is required and advised me to demolish the thing and build a new one in principle, just like the other craftsmen who saw it did as well.. Ultimately, I have now come to the conclusion and now plan demolition and rebuilding.. At an info day (building authority Cologne) the employee told me that I can build as high as the neighbor!! That means my right neighbor has a mid-terrace house of the same height and the left neighbor house is a multi-family house (3 floors + attic with residential units). So, in principle, I may build that high!! That means one more floor for me. I want to use the first two floors myself (maisonette apartment), and I would then like to rent out the third floor as well as the attic. But I have no experience at all and do not know exactly what I have to do except get a permit.. I look forward to your valuable tips.

I would not make any hasty decisions. I initially doubt that the house is ready for demolition. This should not primarily be decided by a carpenter, but by an architect in collaboration with a structural engineer. Apart from that, demolition can be quite costly, for example if neighboring buildings need to be secured or if a basemented new building must potentially be founded deeper than the neighboring buildings. It is also possible that the existing use protection expires and a new building may no longer be erected in the same form. This can only be assessed on site.

A house built in 1900 can basically be completely renovated, which would be the usual approach. Almost always, the roof structure must be renewed because the rafter layout is undersized and cannot accommodate the required roof insulation according to the Energy Saving Ordinance. With a new roof construction, the roof structure can possibly be raised to allow the attic to be converted into living space. The attic conversion is basically subject to a building permit, as is the renewal of the rafter structure. The carpenter cannot carry this out independently. In addition, you need a renovation concept for the complete renovation of the house in relation to the entire building, in which all trades are coordinated.

If demolition is unavoidable or the best solution for a intended new use at this location, it must first be clarified from a building and planning law perspective what type and extent of new development are possible. The development plan provides information about this; it must be interpreted by an architect and negotiated with the building authorities in order to be able to build the design you desire. If no development plan exists, the procedure according to §34 of the Building Code must be followed: the building project should correspond to the built environment. For this, a preliminary building inquiry must be submitted.

You should therefore commission an architect to 1.) inspect the property and assess the condition of preservation, and then discuss the desired construction measures with you if the object is worth preserving. If it is 2.) actually ready for demolition, the architect can prepare a preliminary design for your construction project, if a development plan exists or after assessing the situation, and coordinate this with the building authorities for feasibility.

No decisions should be made without an architect and an independent expert assessment of the existing situation. Where is the property located in Cologne?

It is the green house in the photo And thank you for the detailed answer the house is located at 51105 Cologne on Rolshover Street so not only the carpenter but also the craftsmen I trust have given me the same advice

Year of construction approx. 1900 and the dimensions 6.15m wide

Six meters fifteen is still just as narrow today as it was back then, so I don't expect much potential for improvement from a new building that would justify the extra effort. On the other hand, the house looks too well maintained to consider demolition hastily. Both together are, in my view, good arguments to have an architect experienced with old buildings take a closer look.

At an info day (building authority Cologne) the staff member told me that I can build as high as the neighbor!!

Keep in mind that this information is by far not equivalent to a building pre-approval. At info days, many "text modules" are conveyed. It is nothing more than an FAQ collection presented in person. In a §34 situation, I would fear that the more similar neighbor is weighted as more decisive – unless the taller house is the successor of two houses in the format of the two small ones.

The usual and proven procedure to arrive at a usable result for further action would be:

1. Construction consultation appointment with an architect as an on-site meeting: Assessment of the quality and condition of the load-bearing and non-load-bearing building structure for renovation/conversion/extension/expansion. For this purpose, building components may also need to be opened (ceiling/wall constructions). Of particular interest is always the condition of the ceiling above the basement – probably a steel beam ceiling with masonry caps – and the wooden beam ceiling above the top floor for the extension or the addition of the attic.
2. When using the existing structure: Building survey + preparation of current as-built drawings, development of a renovation concept/renovation schedule, clarification of building and planning law possibilities and static requirements for the attic conversion/addition, cost estimation, possibly preliminary building inquiry, building application, etc.
3. In case of demolition: Clarification of the building and planning law framework conditions for a new building, if necessary negotiations with the authorities according to §34 of the Building Code and missing development plan, possibly preliminary building inquiry, preliminary design with cost estimation and calculation of demolition costs, etc., and further processing as a building application up to building realization.

Hi Bastürk, what can you afford?