ᐅ Demolition and New Construction – How to Make Effective Use of a 761 m² Plot?
Created on: 12 Nov 2025 11:05
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carstenhh
Hello everyone,
We have purchased a 761 m² (8,194 sq ft) plot with an existing building in Hamburg. Originally, the plan was to fully renovate the old house, but the condition is unfortunately so poor that we have now decided to demolish it and build new.
Since this is a corner lot and there is no formal zoning plan (building permit / planning permission) in place, the project will be evaluated under Section 34 of the Federal Building Code (Baugesetzbuch). There are already similar developments nearby, so we are allowed to build two units. The site coverage ratio is officially 0.20, but since neighboring plots are clearly built more densely, we realistically assume 0.25. One full story and one half story are permitted. We want to build without a basement.
Our initial dream was a single-family home that makes good use of the plot. We have two children and currently live in cramped conditions, so owning our own house would be a big step. However, building new will be financially challenging, so we are currently considering selling part of the plot and instead planning a semi-detached house (duplex) — so that we retain more land and can remain as independent as possible from the neighbor.
We want to build as cost-effectively as possible, but it doesn’t have to be a prefab house — I am open to ideas, suggestions, or alternative solutions on how to implement the project sensibly. Approximately 140 m² (1,507 sq ft) of living space would be perfectly sufficient for us.
Does anyone have experience or tips regarding:
I look forward to your assessments, experiences, or creative ideas on how to solve this project cleverly.
Best regards,
Carsten from Hamburg
We have purchased a 761 m² (8,194 sq ft) plot with an existing building in Hamburg. Originally, the plan was to fully renovate the old house, but the condition is unfortunately so poor that we have now decided to demolish it and build new.
Since this is a corner lot and there is no formal zoning plan (building permit / planning permission) in place, the project will be evaluated under Section 34 of the Federal Building Code (Baugesetzbuch). There are already similar developments nearby, so we are allowed to build two units. The site coverage ratio is officially 0.20, but since neighboring plots are clearly built more densely, we realistically assume 0.25. One full story and one half story are permitted. We want to build without a basement.
Our initial dream was a single-family home that makes good use of the plot. We have two children and currently live in cramped conditions, so owning our own house would be a big step. However, building new will be financially challenging, so we are currently considering selling part of the plot and instead planning a semi-detached house (duplex) — so that we retain more land and can remain as independent as possible from the neighbor.
We want to build as cost-effectively as possible, but it doesn’t have to be a prefab house — I am open to ideas, suggestions, or alternative solutions on how to implement the project sensibly. Approximately 140 m² (1,507 sq ft) of living space would be perfectly sufficient for us.
Does anyone have experience or tips regarding:
- Building under Section 34 of the Federal Building Code (without a zoning plan)?
- Partial sale of a plot when building a semi-detached house?
- Affordable construction methods or turnkey homes (solid / prefab)?
- Designing a semi-detached house with as little contact as possible to the neighbor (e.g., staggered building volumes, separate driveways, soundproofing, etc.)?
I look forward to your assessments, experiences, or creative ideas on how to solve this project cleverly.
Best regards,
Carsten from Hamburg
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carstenhh12 Nov 2025 15:09The plot is already in
Thank you, that’s a really good tip – it sounds absolutely logical and understandable to me. I find the approach of planning the duplex as a joint “module” and handing over the second half only after the shell construction very reasonable.
11ant schrieb:
In a single-story house design – meaning with a converted pitched roof – having an offset creates complications for the building profile on the community side. It will likely be difficult to secure financing if you try to act as a developer inexperienced and as a first-time builder. However, that is not necessary to be a major project partner in the planning phase. The most cost-effective approach is usually to build a simple building form with a provider from the appropriate level of finishes. Shell-and-core houses are much more worthwhile for DIY builders than for single contractors delivering turnkey projects. Whether to build wooden or masonry construction should never be decided before the key planning decisions during the initial waiting phase.
First, design "Module A" for the entire duplex, then offer the half to be sold with joint further planning, ideally only up to the shell construction – this way, the co-builder can also independently arrange the finishing trades. The boundary lines can then be determined depending on the community side once the planning is settled.
Thank you, that’s a really good tip – it sounds absolutely logical and understandable to me. I find the approach of planning the duplex as a joint “module” and handing over the second half only after the shell construction very reasonable.
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motorradsilke12 Nov 2025 15:10What is your budget? I would first check out affordable providers, for example Town & Country, to find a pre-designed floor plan and consider whether it is affordable. Keep customization to a minimum, plan for additional building-related costs (e.g., permits, connection fees), and do the landscaping yourself later.
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carstenhh12 Nov 2025 15:13carstenhh schrieb:
Thank you for your detailed answer. That really helps me a lot.
Regarding the floor area ratio: According to the documents, it is actually 0.20 for my plot, but since the neighbors have all built with higher density, I assume I can go up to 0.25. That would mean about 190 m² (2,045 sq ft) of buildable area, enough for a small semi-detached house. If it remains at 0.20, it will get really tight – then probably only a smaller single-family house would fit.
About Section 34 of the Federal Building Code (BauGB): I will follow the character of the neighborhood. There are several semi-detached and single-family houses here, so nothing unusual is planned. Simple, fitting, and affordable.
Regarding the partial sale, I plan to handle it as a concept sale. That means: I will have the semi-detached house fully designed, with a clear division and two separate driveways. Then I would sell one half including the design and building permit. This way I maintain control over the architecture and location, and the buyer benefits from having everything already prepared.
On the topic of costs: I don’t want a "cheap house," but a simple, efficient home – rectangular, without a basement, and with a pitched roof. I can do some work myself (painting, flooring, electrical work, possibly drywall) with help from family (some professionals in the industry among them) and friends.
And yes, I have come to see the issue of privacy more realistically. It’s not about not seeing anyone, but simply about a clear separation: separate driveways, private terraces. Thanks to the corner location, this should be feasible.
Best regards,
Carsten The plot is already owned, so I won’t say anything about costs. My original budget was actually meant for a renovation – I had planned for a maximum of 150,000 euros. But since the existing building can no longer be saved, I now obviously have to increase the budget significantly for the new construction.
That’s why I am thinking about building as cost-effectively as possible or possibly selling one half to be able to finance the whole project.
And yes – this probably could have been clarified earlier, whether renovation was possible or not, I hear that quite often from others as well.
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nordanney12 Nov 2025 15:22carstenhh schrieb:
My original budget was actually intended for a major renovation – I had calculated a maximum of 150,000 €.A 140 m² (1507 sq ft) new build as a semi-detached house will already cost you around half a million, including additional costs.That really leaves only the options of tapping into substantial personal savings, arranging significant financing, or subdividing the plot.
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carstenhh12 Nov 2025 15:33nordanney schrieb:
A 140 sqm (1507 sq ft) new build – as a semi-detached house – will already cost you half a million including additional costs.
That really leaves only the option of accessing substantial personal savings, securing large financing, or splitting the plot.I believe you. Well, the original dream was actually a detached single-family house. The question here is how affordably I could get a "simple" single-family home with about 130–140 sqm (1400–1507 sq ft) of living space. 🙁
carstenhh schrieb:
Thank you, that’s a really good point – it sounds completely logical and understandable to me. I find the approach of planning the duplex as a shared “module” and handing over the second half only after the shell construction very sensible. You have generously misunderstood me. My suggestion is strategically aimed at designing the entire duplex but initially only as “Module A” (see “A construction schedule, also for you: the HOAI phase model!”), meaning up to the preliminary design stage. During the > resting phase, you then make the > key decisions and determine the more cost-effective construction method. Also, in this phase, you sell the second half including the yet unmarked plot share (two separate parcels legally divided but with an undetermined boundary) along with submission to a joint design and shell construction contract.
motorradsilke schrieb:
I would first look at the affordable suppliers, for example Town & Country, for a finished floor plan and consider whether it is affordable. This and similar providers do not operate in the “serial building” market segment, from which the most effective duplex models come, but are distinctly single-family house-focused. I am thinking here of a custom design as mentioned, up to the resting phase and key decisions, a shared shell construction, and then proceeding separately afterwards (so, not move-in ready either, whereas the mentioned provider would be an economy move-in ready general contractor).
carstenhh schrieb:
The question here would be how cheap I could get a “simple” single-family house with about 130-140 sqm (1400-1500 sq ft) of living space. The “GDB bottle” from the “usual suspects” offers 140 to 145 sqm (1500 to 1560 sq ft) over two and a half storeys and is therefore not suitable for adaptation here.
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