ᐅ Semi-detached house in Hamburg with a general contractor on own land, two plus full attic floors, no basement
Created on: 26 Jul 2025 12:27
1
1689owen
I’m looking for feedback on anything we might have overlooked. Tips on processes and organization are also helpful. (Details about the location, plot, and contractors involved will be shared later to keep things anonymous for now.)
We want to build a duplex and hire a general contractor (GC) for this. Each party has about €40,000 (approximately $44,000) available. The scope of self-performed work will differ slightly between the two parties but will mainly be limited to painting (including plastering and all related work) and flooring (excluding bathrooms). The attic may possibly be finished as self-performed work.
We have a few requirements:
According to the plans, we may build two full stories. We want to retain as much garden space as possible and, for this reason among others, would like to add a fully functional attic. By “fully functional,” we mean it can be used as living and working space and forms its own separate part of the apartment—not an open area connected to the stairwell (for example, the parents’ bedroom would be here). We were advised that having a concrete floor between the upper floor and attic would be sensible to achieve this. The attic could also be raised with a knee wall (dormer wall), which would greatly improve the interior height. Since the plans don’t specify maximum ridge, eaves, or gable heights, it will likely be restricted only by required setback distances. The setback to the neighboring plot is currently set at 3 meters (about 10 feet) for driveway, bike storage, and garage as border construction. This leaves a good garden area on the other side of the house.
kfw300 program:
This is very helpful for financing, almost essential for us. However, it comes with certain requirements that may cause additional costs. Which parameters would you recommend adjusting here?
Current status:
We have discussed financing preliminarily and set a budget framework. We already own the land. We are currently in talks with several GCs (ranging from smaller architecture firms, medium-sized companies, to larger firms like Baudirekt). We plan to decide on a GC in about a month. The options each GC offers will understandably influence our decision. We also still need to clarify whether we truly need and can afford a fully finished attic or if a pitched roof attic that could be finished later would suffice. A basement would probably be more expensive and provide less livable space than a full attic, so it is no longer a serious option. We plan to consult two or three more GCs to get feedback on possibilities and pricing.
Please feel free to ask any questions! This is already a lot of help. Maybe there’s even some additional advice out there. Thanks!
We want to build a duplex and hire a general contractor (GC) for this. Each party has about €40,000 (approximately $44,000) available. The scope of self-performed work will differ slightly between the two parties but will mainly be limited to painting (including plastering and all related work) and flooring (excluding bathrooms). The attic may possibly be finished as self-performed work.
We have a few requirements:
- Each party: 2 adults (bedroom, office) + 3 children (individual bedrooms)
- Total house footprint around 165m² (approximately 1,775 sq ft). A preliminary building inquiry has already been made.
- Noise protection necessary due to aircraft noise.
- Full attic living space
- kfw300 program
- Solid construction
- Brick facade
- Pitched roof
- Central ventilation system
- For both parties: rooms should not be too large (e.g., child’s room 10m² (110 sq ft), office 8m² (86 sq ft)); only one large open area for living and kitchen.
- Each half of the building should be easily separable in the future into an accessible unit (basement) and an apartment (upper floor + attic).
According to the plans, we may build two full stories. We want to retain as much garden space as possible and, for this reason among others, would like to add a fully functional attic. By “fully functional,” we mean it can be used as living and working space and forms its own separate part of the apartment—not an open area connected to the stairwell (for example, the parents’ bedroom would be here). We were advised that having a concrete floor between the upper floor and attic would be sensible to achieve this. The attic could also be raised with a knee wall (dormer wall), which would greatly improve the interior height. Since the plans don’t specify maximum ridge, eaves, or gable heights, it will likely be restricted only by required setback distances. The setback to the neighboring plot is currently set at 3 meters (about 10 feet) for driveway, bike storage, and garage as border construction. This leaves a good garden area on the other side of the house.
kfw300 program:
This is very helpful for financing, almost essential for us. However, it comes with certain requirements that may cause additional costs. Which parameters would you recommend adjusting here?
Current status:
We have discussed financing preliminarily and set a budget framework. We already own the land. We are currently in talks with several GCs (ranging from smaller architecture firms, medium-sized companies, to larger firms like Baudirekt). We plan to decide on a GC in about a month. The options each GC offers will understandably influence our decision. We also still need to clarify whether we truly need and can afford a fully finished attic or if a pitched roof attic that could be finished later would suffice. A basement would probably be more expensive and provide less livable space than a full attic, so it is no longer a serious option. We plan to consult two or three more GCs to get feedback on possibilities and pricing.
Please feel free to ask any questions! This is already a lot of help. Maybe there’s even some additional advice out there. Thanks!
Earlier, I overlooked a point...
... and I also missed another one:
It would be helpful to report on the result of the preliminary building inquiry.
Discard the nonsense about dividability. This is a highly critical dealbreaker that can ruin many plans and significantly increase the costs of all others to such an extent that demolition would have been the lesser evil. In case of serious issues, changing the property is by far the more cost-effective solution.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
1689owen schrieb:
Total building footprint around 165m² (1,776 sq ft). There was already a preliminary building inquiry regarding this.
... and I also missed another one:
1689owen schrieb:
Each half of the house can easily be divided in the future into an accessible unit (basement) and a living space (first floor + attic).
It would be helpful to report on the result of the preliminary building inquiry.
Discard the nonsense about dividability. This is a highly critical dealbreaker that can ruin many plans and significantly increase the costs of all others to such an extent that demolition would have been the lesser evil. In case of serious issues, changing the property is by far the more cost-effective solution.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
Edith, I was too late to add this:
The KfW only grants funds within the budget allocated by the federal government (voluntary benefits). In case no one has noticed yet, there is still no approved federal budget, meaning the KfW is still using last year’s federal funds. Once those run out, nobody knows what will happen. If new funds are provided for this fiscal year, will the program be discontinued or relaunched? That could put you in a difficult situation...
The KfW only grants funds within the budget allocated by the federal government (voluntary benefits). In case no one has noticed yet, there is still no approved federal budget, meaning the KfW is still using last year’s federal funds. Once those run out, nobody knows what will happen. If new funds are provided for this fiscal year, will the program be discontinued or relaunched? That could put you in a difficult situation...
I personally don’t understand why it’s not possible to provide information like, for example, 20x40 meters (65x131 feet), or to post a hand-drawn sketch of the plot showing orientation, dimensions, streets, and the neighborhood.
Well, Hamburg, maybe Schnelsen or something similar (doesn’t really matter), no one cares about that either.
And the requested companies are not really relevant if you are dealing with them directly.
The most important aspect is that a) you can hardly build living space for under 3000 €/m² (about $280/sq ft). If expensive soundproof windows are also required, then definitely not.
So with €400,000 you won’t get 165 m² (around 1,775 sq ft) built.
The second big mistake is thinking that b) you can simply split a house on a relatively small plot into two adequate apartments.
How do you imagine flat living on 65 m² (700 sq ft) minus technical rooms minus staircase?
That leaves you with about 53 m² (570 sq ft) including a tiny shower bathroom, which is hardly functional. Then an 8 m² (85 sq ft) small office is supposed to serve as a bedroom?! That is not barrier-free just because it is on the ground floor.
Upstairs there’s a family bathroom, but no outdoor space. Also, no adequate parking space for two households.
Thoughts like these are so secondary that they stand in the way of planning a simple and functional residential building.
Who advised that? That’s nonsense! Why should concrete be better when it comes to your own house?
Otherwise, all wooden houses and prefabricated houses wouldn’t be considered full value?!
I don’t understand the repeated use of that word anyway. The opposite of “full value” is “inferior.”
The only thing that comes to mind is that your divided units are more likely to be inferior because they are neither comfortable nor adequately livable.
But now, let’s get to the point: show us the draft!
1689owen schrieb:
Details about location, plot, and requested companies will be shared later, so it remains anonymous for now.
Well, Hamburg, maybe Schnelsen or something similar (doesn’t really matter), no one cares about that either.
And the requested companies are not really relevant if you are dealing with them directly.
1689owen schrieb:
Or where are we thinking wrong?
The most important aspect is that a) you can hardly build living space for under 3000 €/m² (about $280/sq ft). If expensive soundproof windows are also required, then definitely not.
So with €400,000 you won’t get 165 m² (around 1,775 sq ft) built.
The second big mistake is thinking that b) you can simply split a house on a relatively small plot into two adequate apartments.
How do you imagine flat living on 65 m² (700 sq ft) minus technical rooms minus staircase?
That leaves you with about 53 m² (570 sq ft) including a tiny shower bathroom, which is hardly functional. Then an 8 m² (85 sq ft) small office is supposed to serve as a bedroom?! That is not barrier-free just because it is on the ground floor.
Upstairs there’s a family bathroom, but no outdoor space. Also, no adequate parking space for two households.
Thoughts like these are so secondary that they stand in the way of planning a simple and functional residential building.
1689owen schrieb:
We were advised that a concrete ceiling between the first floor and the attic would be useful for full value.
Who advised that? That’s nonsense! Why should concrete be better when it comes to your own house?
Otherwise, all wooden houses and prefabricated houses wouldn’t be considered full value?!
I don’t understand the repeated use of that word anyway. The opposite of “full value” is “inferior.”
The only thing that comes to mind is that your divided units are more likely to be inferior because they are neither comfortable nor adequately livable.
But now, let’s get to the point: show us the draft!
That’s helpful! Please continue like this.
If this could be discarded as “easily” as the other point, that would clarify things. BUT...
That brings up the question of how financing is going to be managed without subsidies (or maybe with ifb from Hamburg? I don’t know their terms...). If I’m not missing anything, higher overall interest rates and limits on loan duration and payment amounts already close the door under 40,000 euros. So, where/how should we proceed here? What would you advise? We will certainly consult financial advisors again but it can’t hurt to have a few ideas beforehand.
Your advice, @11ant, was even to select companies independently (and possibly separately) after the shell stage. I think we would prefer some organizational simplicity here if cost permits. But maybe that conflicts with the other goals?
Thanks a lot anyway!
11ant schrieb:
... and I overlooked another point:
>> Each half of the duplex can in future be easily separated into an accessible unit (basement) and an apartment (first floor + attic). <<
[...]
Discard the nonsense about separability. This is a highly critical killer criterion that can ruin many plans and drastically increase costs to the point where demolition would have been the lesser evil. Changing properties in an emergency is by far the cheaper solution.
Rübe1 schrieb:--> Ok, it’s been discarded. We can “easily” let that go.
That alone already requires a design concept that you can’t just pull out of thin air.
Rübe1 schrieb:I’m not really familiar with this. I’ve done some research but can’t estimate what the structural and cost differences are between KfW 55 vs KfW 40 vs KfW 40+ (compared to KfW 40+QNG, which we definitely do not want). We were told that energy consulting would cost around 10,000-15,000 euros, but presumably there would also be cost increases in design and materials. It’s not absolutely necessary for us. But I thought the requirements in Hamburg were not far from KfW 40 (+), so I have probably been quite mistaken.
KfW 300, do you know the conditions? It’s like Program 297, so basically KfW 40+ . And beyond that, there is the CO2 balance and all that. To use a colleague’s words, that is not so easy with solid construction, especially with concrete ceilings and clinker brick façades...
If this could be discarded as “easily” as the other point, that would clarify things. BUT...
That brings up the question of how financing is going to be managed without subsidies (or maybe with ifb from Hamburg? I don’t know their terms...). If I’m not missing anything, higher overall interest rates and limits on loan duration and payment amounts already close the door under 40,000 euros. So, where/how should we proceed here? What would you advise? We will certainly consult financial advisors again but it can’t hurt to have a few ideas beforehand.
11ant schrieb:The two parties have a very good relationship, share many commonalities, and would like to support each other. So we intend to decide as many framework conditions as possible together, although the details and especially decisions about what work is done by themselves will differ — but neither party will do entire construction phases on their own.
It’s very sensible that you understand the duplex as a whole. You only need a common general contractor at the shell construction stage; the finishing can be contracted out separately by each neighbor.
Your advice, @11ant, was even to select companies independently (and possibly separately) after the shell stage. I think we would prefer some organizational simplicity here if cost permits. But maybe that conflicts with the other goals?
11ant schrieb:Where does the advice regarding timber frame come from? We have so far been focusing only on masonry and solid construction. What have we missed?
I would recommend requesting a further general contractor (two specializing in masonry and two in timber frame) — overall I usually consider five or six bids. In Hamburg you should also be able to find inspiration from developer house concepts (the nationally available are mostly two-story + attic with about 140/145 sqm (1507/1565 sq ft)).
11ant schrieb:
By the way, a knee wall doesn’t help standing height; that would require a wall plate (which usually breaks the full-story height limit).
Rübe1 schrieb:I meant a wall plate (kniestock), sorry. We don’t really have issues with the full-story height limit or setbacks because this concerns the side clearance. Of course, some details need to be clarified, but I don’t see any problems. However, it’s possible I’m overlooking something (which is quite likely, since I currently feel like I’m missing everything). I might open another thread soon, where I’ll post drawings and raise questions on the prioritization of roof pitch, story height, etc.
OK, did you understand it? On page 7 is exactly your case. You are “planning” with a 3-meter (10 ft) setback. In one case 2.8m (9.2 ft) clearance is allowed; in another case, not with 3.6m (11.8 ft), assuming the ridge height "H2" is really just 3m (10 ft). This severely restricts your plans.
11ant schrieb:The duplexes with two stories plus attic that I found quickly on a few other platforms all had a studio-type layout upstairs, so a concrete ceiling plus knee wall would probably require significant redesign and additional costs. Right?
Using developer house concepts as inspiration (the nationally available are mostly two-story + attic with about 140/145 sqm (1507/1565 sq ft))
Rübe1 schrieb:One more thing on this (I think I understand better now where this advice comes from): So, should we visit an architect’s office and have a plan drawn up? That certainly costs money. If I then build with another general contractor, that money might partly be lost. Or should we first look for a few more general contractors, modify their standard designs, and get quotes? And only then consider an architect? What would you advise here — and what is that advice based on?
Aside from the wishes, the requirements are so very individual that this is something for a planner.
Thanks a lot anyway!
N
nordanney26 Jul 2025 18:061689owen schrieb:
So, should I consult an architectural firm and have a design done? But that will probably cost money. If I then build with a different general contractor (GC), that money might be (partially) lost. 1. The money is not lost; it just goes to someone else.
2. Every design costs money. If an architect does it, you see the invoice; if the GC designs it, the cost is included in the overall price.
3. With a design from an architect, you can either a) build with solid construction (e.g., masonry or concrete) or b) use a timber frame structure, and both options can be done 1. with a GC or 2. with individual trades.
nordanney schrieb:
1. The money isn’t lost, it’s just with someone else.
2. Every plan costs money. With an architect, you see the invoice clearly; with a general contractor (GC) handling the planning, the cost is included in the overall price.
3. With an architect’s plan, you can either a) build with solid construction (e.g. masonry) or b) use timber frame construction, and both options 1. with a GC or 2. with separate trades. Well, the money is gone from my point of view. It’s then with the architect. But perhaps a GC, working according to their own process, might want to create their own (re)planning as well, which would cost me money again, so I end up paying twice in part and stuck with the extra costs. Or am I misunderstanding something?
__
ypg schrieb:
The second big mistake is thinking that b) you can simply divide a relatively small footprint house into two proper apartments.
How do you imagine living on one level in about 65m² (700 sq ft) minus a utility room minus the staircase?
That leaves roughly 53m² (570 sq ft) with a tiny shower/toilet that is hardly usable. Then an 8m² (85 sq ft) small office that is supposed to serve as a bedroom?! That wouldn’t be barrier-free just because it’s on one level.
Upstairs there is a family bathroom, but no extra space. Plus no adequate parking area for two separate units.
These considerations are so secondary that they actually hinder the design of a simple, functional home. See just now (we wrote at the same time). It’s already moved to the trash. That might simplify this entire thread here.
ypg schrieb:
The most important point is that a) you can hardly build living space for less than 3000€/m² (about $280/sq ft). And if expensive soundproof windows are needed, then definitely not.
For €400,000 you won’t get 165m² (1775 sq ft) built. First: No idea what actual building requirements come with the aircraft noise. Triple glazing?
Second: We don’t actually need 165m² (1775 sq ft).
(a) I probably didn’t express myself clearly:
1689owen schrieb:
1689owen schrieb:
The total house footprint is about 165m² (1775 sq ft) What I meant is: On the site, 165m² (1775 sq ft) of lawn area will be turned into 165m² (1775 sq ft) of concrete slab. Each half of the house has a ground floor footprint of 164m²/2 = 82m² (883 sq ft), so a living area of about 0.7x82m² = 57.4m² (618 sq ft). Counting ground floor + first floor + attic, I get approximately 172.2m² (1853 sq ft) of floor area, which is not all living space due to the attic. Maybe 165m² (1775 sq ft) is even a fitting number.
(b) We can accept losing a few square meters, but having a “full” attic (more on that below) would be nice and practical.
Maybe like this (all measurements just rough estimates):
Ground floor: living-dining-kitchen area (30m²/320 sq ft), utility (8m²/86 sq ft), guest bathroom (one side shower) (5m²/54 sq ft), rest (14m²/150 sq ft) split between hallway and another room (guest/office).
First floor: bathroom (10m²/108 sq ft), three kids’ rooms (3x10m²/3x108 sq ft), one more room (guest/office, 10m²/108 sq ft), rest hallway (7m²/75 sq ft).
Attic: master bedroom, possibly an office, one side also a bathroom with shower.
The master bedroom can be small. But it would be nice to have that third level with separate rooms so parents can be reasonably separated from children. Maybe the attic doesn’t need to have a concrete ceiling, but if walls and proper heating and ventilation are planned, we’d need to consider that... The budget obviously limits this. Which direction would make sense to explore further? Planning without an attic? Planning the loft for future conversion but waiting for now (while parents live upstairs, therefore no guest room)? Using the attic only for storage (and if so, what do we sacrifice downstairs to have one more room)?
ypg schrieb:
Who recommends that? That’s nonsense! Why should concrete be better when it’s your own house?
Otherwise, all wood and prefab houses would not be fully functional..!?!
I don’t get this repetition of the word “full.” The opposite of “full” is “inferior.” As described earlier: Walls and proper connections to heating and ventilation in the attic. BUT: Please ask more questions, maybe there is something here we haven’t fully thought through yet.
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