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!
In der Ruine16 Apr 2025 17:03I want to step in and support the "victim" here. I also don’t understand why he is supposed to be at fault. He approaches the general contractor, requests a KFW40 house, and specifies the size with so much living space. The person who made the initial sketch clearly missed something. That can happen. But the professional draftsman should have noticed this and clarified it with the client. Something like, "Unfortunately, this isn’t feasible, but here are some possible alternatives." Just handing him the final plan without any comments is, in my opinion, not the proper way to handle it.
ITSM2025 schrieb:
Could you please clarify that? Why is this my fault? I communicated to the general contractor from the beginning what I wanted. In response, he created that colorful sketch with the respective areas shown as numbers in the middle of the rooms. I don’t understand, sorry. I’m not an expert. It’s not only you who isn’t an expert; the draftsman isn’t either. That’s probably why the conflict between the calcium silicate blocks and the EH40 in the colorful sketch went unnoticed. With a structural cavity wall shell made of calcium silicate blocks size 175, achieving a U-value for EH40 is simply not possible. So the draftsman must have switched to calcium silicate blocks size 240, and the overall wall thickness accordingly increased. You can easily use calcium silicate blocks for the interior walls and mix in aerated concrete for the exterior walls; this way, the overall wall thickness increase can be reversed. Viebrockhaus builds EH40 as standard, with a total wall thickness of 44 cm (17 inches), featuring a 15 cm (6 inches) thick structural cavity shell made of aerated concrete. However, this would be an out-of-system total wall thickness, where the difference to the octameter module should be properly compensated on the interior side. You might want to name the exact wall assembly planned before the change.
In der Ruine schrieb:
I want to support the “victim” here. I don’t understand why he should be to blame. He goes to the general contractor, wants a KWF40 house, and specifies the size and floor area. So the sketch creator dropped the ball. It can happen. The original poster (OP) is not a “victim” but the cause of this easily fixable problem. You cannot simply swap in a block with a poor U-value without consequences (which a draftsman usually does not foresee).
In der Ruine schrieb:
But by the time the proper draftsman got involved, they should have been suspicious and clarified this with the customer. Something like “Unfortunately, this is not feasible, but here are some options…” Just throwing the finished plan at him without comments is not very professional. As the OP has since admitted (in post #16), it wasn’t exactly dropped on him without warning.
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Ultimately, things are as they are now, and it is best to assume that neither party intended anything dishonest or malicious; often, it is a mix of factors or mutual expectations towards each other.
If the general contractor (GC) is reliable, the original poster (OP) already has an advantage that not all homeowners are granted, and this issue can likely be resolved through discussion.
I have experienced GCs who were not very knowledgeable about KfW standards; mine was even an energy consultant in addition, but for KfW40 he gave up because his software couldn’t handle it. Fortunately, I found a truly competent energy consultant quite far away, as they are quite rare.
What I wonder is whether the current or now corrected floor plan is actually intended to be built, so that the discussion should only focus on this “misunderstanding.”
If the OP would like to discuss the floor plan as well, they should start from scratch here, with the questionnaire and the plans. Otherwise, people would always have to search through the entire thread for everything as it is now.
Regarding the KfW40 insulation standard, which I find better, I’m essentially indifferent about how it is produced, since extra layers will be added on both sides anyway.
If the general contractor (GC) is reliable, the original poster (OP) already has an advantage that not all homeowners are granted, and this issue can likely be resolved through discussion.
I have experienced GCs who were not very knowledgeable about KfW standards; mine was even an energy consultant in addition, but for KfW40 he gave up because his software couldn’t handle it. Fortunately, I found a truly competent energy consultant quite far away, as they are quite rare.
What I wonder is whether the current or now corrected floor plan is actually intended to be built, so that the discussion should only focus on this “misunderstanding.”
If the OP would like to discuss the floor plan as well, they should start from scratch here, with the questionnaire and the plans. Otherwise, people would always have to search through the entire thread for everything as it is now.
Regarding the KfW40 insulation standard, which I find better, I’m essentially indifferent about how it is produced, since extra layers will be added on both sides anyway.
11ant schrieb:
The original poster (OP) is not a "victim" but the cause of this easily fixable small problem. You can’t just swap a stone with a poor U-value without consequences (which a draftsman usually doesn’t foresee). That’s nonsense. If KfW 40 standards were clearly communicated, in my opinion the OP is 100% right. What if the furniture had already been selected accordingly? What really matters is what is written in the contract. What exactly are you buying? If the contract states a house with x square meters of living space, then the general contractor (GC) can’t just reduce that.
11ant schrieb:
Not only are you not a specialist, but neither is the draftsman. That’s probably why the conflict between calcium silicate brick and EH40 in the colorful sketch hasn’t been noticed yet. With a structural wall shell made of calcium silicate brick, size 175, a U-value for EH40 simply can’t be achieved. So the draftsman must have switched to calcium silicate brick, size 240, which caused the overall wall thickness to increase accordingly. I think you may have misunderstood something here. From the start, the plan was for a KfW 40 house. For that, I specified calcium silicate brick 17.5cm (7 inches) + insulation + 11.5cm (4.5 inches) facing brick. As it turns out (according to the last email from the general contractor), an insulation thickness of 13.5cm (5 inches) was assumed for the sketch. This insulation has now been planned 6.5cm (2.5 inches) thicker, which caused the still 17.5cm (7 inches) calcium silicate brick wall to be shifted inward. I hope I have made this clearer now. Does this possibly change your opinion?
K a t j a schrieb:
What exactly are you buying? If the house is listed with a certain square meter living area, the general contractor (GC) can’t just reduce that. Normally, it’s much more critical to exceed the originally planned external dimensions. A floor plan where rooms don’t work anymore if they are 6.5 cm (2.6 inches) narrower would be a faulty design.
ITSM2025 schrieb:
I think you misunderstood something here. From the beginning, it was planned as a KfW 40 house. I specified sand-lime brick 17.5 cm (7 inches) + insulation + 11.5 cm (4.5 inches) facing brick. As it turned out (latest email from the GC), the sketch assumed insulation thickness of 13.5 cm (5.3 inches). This insulation is now planned 6.5 cm (2.6 inches) thicker, which caused the still 17.5 cm (7 inches) sand-lime brick wall to be shifted inward. I hope I have made this a bit clearer now. Does this possibly change your opinion? Assuming a cavity of 13.5 cm (5.3 inches) is standard practice and usually accounts for about 12 cm (4.7 inches) insulation thickness plus an air gap. The typical GC standard here would likely be a structural outer shell made of calcium silicate brick or aerated concrete. Since sand-lime brick has a significantly higher U-value and 12 cm (4.7 inches) of insulation offers limited potential to compensate for that with a more efficient insulation material, a problem arises (which only becomes apparent during the energy demand calculation). Therefore, one of the individual component thicknesses must be increased — here, this was done correctly by dimensioning the cavity to 20 cm (7.9 inches), which represents a necessary step-change. I had already understood you correctly, so my opinion remains the same: move away from sand-lime brick here and use aerated concrete instead; that should solve the U-value issue. Sand-lime brick only has a disadvantage for you in this case. If you want the advantage regarding sound insulation: that mainly applies to interior walls, which remain unaffected by the material chosen for the exterior walls. But a careful reader who has been following this thread for a while should practically be able to recite everything I’ve written here by heart — these are evergreen topics.
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