ᐅ Living area approximately 8 m² smaller in the permit drawings compared to the design (general contractor)
Created on: 16 Apr 2025 11:23
I
ITSM2025
Hi everyone,
Unfortunately, I thought I was smarter than everyone else here in the forum (I have been a quiet reader for a while) and believed I could rely on the general contractor’s planning. Now, right from the start, things are becoming "interesting." I’m not sure whether my frustration is justified or if this is just standard practice in the construction industry. Here’s the situation:
Based on the preliminary design from the general contractor, we awarded the contract (signed the agreement) with the expectation that the room sizes would match the preliminary design. The house is planned as a KfW 40 energy-efficient building with sand-lime brick, insulation, and brick veneer. This was included in the offer along with additional requests, and the design was adjusted accordingly, if necessary. So, it’s not like the general contractor was unaware of our KfW 40 project. Now we have received the building permit drawings showing roughly 8 m² (86 sq ft) less living space due to suddenly thicker walls, both external and internal. The exterior walls were increased from 42.5 cm (17 inches) to 49 cm (19 inches) thickness. And this was done inward, not outward. In other words, each side has lost 6.5 cm (2.5 inches) of interior living space. Calculated in euros, that’s about €22,000 less living area based on the price per square meter. Or, in other words: the general contractor now has to buy fewer sand-lime bricks and build with less material, with less plastering, tiling, screed, underfloor heating, pipes, etc. However, there was no price reduction.
Is this common practice? Should one accept something like this?
Additionally, the attic floor has lost 13 cm (5 inches) in width and 6.5 cm (2.5 inches) of interior height due to the knee wall being shifted further inward. We had planned to convert this space later, which now seems hardly worthwhile. The general contractor knew about this in advance and even planned wiring and such in the attic/roof space.
How do you assess this situation, and how would you proceed?
Thank you very much in advance!
Unfortunately, I thought I was smarter than everyone else here in the forum (I have been a quiet reader for a while) and believed I could rely on the general contractor’s planning. Now, right from the start, things are becoming "interesting." I’m not sure whether my frustration is justified or if this is just standard practice in the construction industry. Here’s the situation:
Based on the preliminary design from the general contractor, we awarded the contract (signed the agreement) with the expectation that the room sizes would match the preliminary design. The house is planned as a KfW 40 energy-efficient building with sand-lime brick, insulation, and brick veneer. This was included in the offer along with additional requests, and the design was adjusted accordingly, if necessary. So, it’s not like the general contractor was unaware of our KfW 40 project. Now we have received the building permit drawings showing roughly 8 m² (86 sq ft) less living space due to suddenly thicker walls, both external and internal. The exterior walls were increased from 42.5 cm (17 inches) to 49 cm (19 inches) thickness. And this was done inward, not outward. In other words, each side has lost 6.5 cm (2.5 inches) of interior living space. Calculated in euros, that’s about €22,000 less living area based on the price per square meter. Or, in other words: the general contractor now has to buy fewer sand-lime bricks and build with less material, with less plastering, tiling, screed, underfloor heating, pipes, etc. However, there was no price reduction.
Is this common practice? Should one accept something like this?
Additionally, the attic floor has lost 13 cm (5 inches) in width and 6.5 cm (2.5 inches) of interior height due to the knee wall being shifted further inward. We had planned to convert this space later, which now seems hardly worthwhile. The general contractor knew about this in advance and even planned wiring and such in the attic/roof space.
How do you assess this situation, and how would you proceed?
Thank you very much in advance!
ITSM2025 schrieb:
The difference now is a loss of 9.57 m² (103 ft²). So you are now even more justified by 1.57 m² (17 ft²); you’re not giving up. No one doubts that you should be able to build the living space you want or that there’s some unclear practice, a misunderstanding, or something else involved here, whether it’s 8 or 18 m² (86 or 194 ft²). The question is how you find that out as quickly and effectively as possible, how you double-check yourself for safety, and—here comes the important part—what you do afterward.
From what I read from you, “raising hell,” taking the legal route, and so on, it seems you think you can intimidate someone, but you fail to see that you are ultimately only harming yourself and will most likely not get “your” right, because courts tend to seek compromises based on experience. How can anyone waste their energy like that? The lawyer will end up with more work.
You seem to overlook or ignore the rather thought-provoking point that you might already have given away just as many expensive square meters unnecessarily yourself, which surprises me considering your comments about 15 years of saving and your loss calculation per square meter.
If the main contractor admits their wrongdoing now and returns the 9-plus m² (97+ ft²), AND you correct your possibly lost square meters, you would have saved twice as much money. But then again, €20,000 (approximately $22,000) potentially wasted would not seem as bad.
So it doesn’t come down to money—it seems more about being right. I’m curious whether you’ll share your outcome with the main contractor here just as openly. It remains interesting.
ITSM2025 schrieb:
Unfortunately, you misunderstood me. The contract before signing was for a KfW 40 single-family house made of 17.5 cm (7 inches) calcium silicate bricks plus insulation (I did not specify any dimensions here) plus 11.5 cm (4.5 inches) facing bricks. I did not know how thick the insulation needed to be to meet KfW 40 standards. I left that to the general contractor (GC). Subsequently, they produced the colorful drawings you have seen. I trusted that these drawings already reflected a wall construction in line with KfW 40 requirements and that we could accept the stated room areas. I never said the entire wall thickness should be based on 42.5 cm (17 inches) blocks. After signing, the GC sent me the information along with the building permit or planning permission drawings that initially a 42.5 cm (17 inches) wall assembly was calculated, which has now unfortunately increased by 6.5 cm (2.5 inches): [ / ]
As I said before, my initial instruction to the GC was calcium silicate bricks 17.5 cm (7 inches) + insulation + 11.5 cm (4.5 inches) facing bricks. No further specifications on insulation thickness or overall wall thickness. I also requested the whole construction to be executed as energy standard 40. I trusted that the sketches created already complied with the requirements for energy standard 40 and that we could rely on the indicated room areas. I never mentioned anything about a 42.5 cm (17 inches) wall thickness. How should I, as a layperson, know how thick the insulation needs to be? On that basis, I placed the order. I did not misunderstand you. You did not explicitly request a 42.5 cm (17 inches) wall thickness, that's correct. However, you expected an overall wall thickness as shown in those colorful drawings, although the necessary architectural services had not yet been completed and those drawings were still provisional target agreements requiring consistency checks. Perhaps the GC should improve customer communication on this matter. Personally, I also consider it better to secure the GC’s effort for plan development through a “deposit solution” (planning services paid in advance and credited upon order) rather than the method of “final drawings only after contract signing.” Naturally, neither party—as laypersons (you nor the draftsman or client advisor)—might have realized that the standard wall thickness could meet energy standard 40 but not in combination with calcium silicate bricks.
ITSM2025 schrieb:
Shortly after, I was sent the building permit or planning permission drawings and the aforementioned additional information:
“According to the requirements of KfW 40 and the preliminary specifications of our structural engineer, we have increased the exterior wall thickness from the original 42.5 cm (17 inches) to 49 cm (19 inches), and planned interior load-bearing walls on the ground floor at 17.5 cm (7 inches), resulting in a slight loss of actual living space, as well as minor shifts in interior walls according to structural requirements. However, this is absolutely necessary.” The phrasing that the 49 cm (19 inches) wall thickness is “absolutely necessary, period” is somewhat unfortunate. Correctly, it should say it is “absolutely necessary, provided you insist on calcium silicate bricks for the structural masonry shell.” There should have been dialogue with you explaining that there are several options:
1. Increase insulation thickness to compensate for the chosen calcium silicate masonry, at the expense of a non-standard total wall thickness;
2. Increase insulation thickness while increasing the overall wall thickness significantly to 49 cm (19 inches);
3. Replace the chosen calcium silicate bricks with aerated concrete blocks to maintain the originally planned wall thickness.
ITSM2025 schrieb:
I already explained how I intend to proceed. Honestly, I don’t see another way to handle this. And yes, of course, I will initially approach this matter objectively and simply ask that the walls be shifted outward so the contractually agreed room areas at least roughly match again. By the way, I recalculated just now with a clearer head and some free time.
The originally planned living area was 164.84 m² (1774 sq ft) according to DIN standards.
The new living area is 155.27 m² (1671 sq ft) according to DIN standards.
The difference is a loss of 9.57 m² (103 sq ft). As I said before, you can easily resolve this with a simple email:
“I am surprised by the total wall thickness now stated as necessary and consider the previously communicated room sizes as agreed. Please shift the increased wall thickness to the exterior, even if this means increasing the overall building dimensions—including height.”
These were harmless communication issues. They became a “problem” only in your mind.
De-escalate by treating them once again as communication shortcomings.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
ITSM2025 schrieb:
The difference is now a loss of 9.57 m² (103.1 sq ft).Don’t stress yourself out! I feel the same way as you do. However, there’s no point in immediately resorting to legal action. First, have a conversation. Present your position, discuss the matter, and most likely renegotiate in the end. The money you would spend on a lawyer is better kept as leverage during negotiations. Also, consider whether you would actually be in a better position elsewhere. And always take time to sleep on it first. Just like now... Good night!M
MachsSelbst18 Apr 2025 09:40I find it quite unlikely that a court would aim for a compromise here. After all, nothing has happened yet that would cause an unreasonable effort for the contractor to fix.
Compromises are made when the shell of the building is already standing and nothing can be changed without tearing everything down again.
Compromises are made when the screed is in place and a radiator was forgotten. Things like that.
Besides that, I would never even consider taking legal action against a contractor at this stage.
Talk to the contractor and ask them to keep the living area as planned.
If that doesn’t work, you need to find another contractor. Then terminate the contract and see if the contractor feels confident enough in their position to claim compensation for their "services performed."
I rather doubt that.
Compromises are made when the shell of the building is already standing and nothing can be changed without tearing everything down again.
Compromises are made when the screed is in place and a radiator was forgotten. Things like that.
Besides that, I would never even consider taking legal action against a contractor at this stage.
Talk to the contractor and ask them to keep the living area as planned.
If that doesn’t work, you need to find another contractor. Then terminate the contract and see if the contractor feels confident enough in their position to claim compensation for their "services performed."
I rather doubt that.
MachsSelbst schrieb:
Talk to the contractor and ask them to keep the living area as planned.
If that doesn’t work, then you need to find another one. Cancel the contract and see if the contractor feels confident enough to sue for compensation for their "services rendered." Well, it seems we finally agree—this was exactly my suggestion and not just mine. Clear communication first, then a clear decision.
MachsSelbst schrieb:
I think it’s quite far-fetched to assume a court would push for a compromise here. After all, nothing has happened yet that would create an unreasonable burden for the contractor to fix. Since you like to highlight your professional experience in a specific field, you should also recognize where your expertise is lacking.
Civil lawsuits very often end in settlements; it’s rare for anyone to get the full 100% of what they want—not because the facts aren’t clear, but often for purely economic reasons. That’s also why threatening legal action is frequently a misfire—or at least a self-inflicted wound. I wanted to warn the original poster about this so-called "threat," which might seem promising but can backfire.
MachsSelbst schrieb:
I rather doubt it. I also advised the original poster against relying on guesses and hopes, and recommended an open, clarifying conversation, just as you explained at the beginning.
By the way, energy standards or proof of compliance can be calculated in two ways. Either by a general rule, where each building component (roof, exterior walls, windows, floor) must meet a specific U-value limit. This limit is probably exceeded here because of thermal bridges.
But there is also the detailed overall calculation. In this case, the heat loss through transmission of the entire building is calculated room by room, allowing lower insulation in one component to be compensated by better insulation in another. This approach is more expensive (both for the verification and most likely the implementation), but it could be a way to keep the original wall thickness.
Additionally, of course, the insulation material could be improved. This is also more expensive, but if it matters, vacuum insulation panels can even be installed (not entirely serious).
Regarding this issue, I recommend what many others here have advised: Ask about the option to maintain the net floor area. The general contractor should be able to offer several alternatives with different consequences.
But there is also the detailed overall calculation. In this case, the heat loss through transmission of the entire building is calculated room by room, allowing lower insulation in one component to be compensated by better insulation in another. This approach is more expensive (both for the verification and most likely the implementation), but it could be a way to keep the original wall thickness.
Additionally, of course, the insulation material could be improved. This is also more expensive, but if it matters, vacuum insulation panels can even be installed (not entirely serious).
Regarding this issue, I recommend what many others here have advised: Ask about the option to maintain the net floor area. The general contractor should be able to offer several alternatives with different consequences.
Similar topics