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:
unfortunately, I was wiser than everyone else here on the forumProof No. 1: You don’t show the design, so we’re supposed to talk about the color blindly; Proof No. 2: You "calculate" that with thicker walls you end up using less (!) material for the walls.
ITSM2025 schrieb:
or if this is simply standard practice in the construction industry.Yes, of course a general contractor’s lackey will take away the space for wall thickening on the inside. Where else? ITSM2025 schrieb:
How do you assess the whole situation and how would you act in this case?If I were you, as the “wiser than the others” client, I would of course send an email: “please recalculate the quote with the wall thickening applied to the outside instead of the inside.” A truly smart client would still discuss and question the entire design here — including in detail, whether the load-bearing block 40 really is the best choice.
And my advisees would also never commit upfront to a particular construction method along with a specific general contractor. They also consult architects who understand and apply a preliminary design as a proven design development stage, not misuse it as a label for a “not yet final” draft.
ITSM2025 schrieb:
I have been a silent reader for a long timeBut at least not a careful one. Otherwise, you would know that by choosing calcium silicate blocks you obviously cannot manage with the 16.5cm (6.5 inches) block dimension in the load-bearing block 40. Sometimes you literally write against a wall here.https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
MachsSelbst schrieb:
Why does the roof absolutely have to be made larger? With a hip roof, the overhang can simply be reduced.However, the overhang is usually specified in the scope of work description. If it is reduced without reason, complaints are justified. So, the roof would necessarily have to be made larger.
MachsSelbst schrieb:
And if 14cm (5.5 inches) more on the exterior dimension becomes a problem, the plot is too small for the planned house anyway.But if you build 6m (20 feet) away from the boundary because you plan a double garage, and then the outer wall thickness increases by 6cm (2.4 inches) afterward, you end up with only 5.94m (19.5 feet) left and the garage no longer fits. Then it doesn’t matter how large the plot is on the other side.
ITSM2025 schrieb:
Besides, we are also paying an extra charge for the upgrade to KfW 40.Which naturally would have been more expensive if the extension had gone outward. That is at least how I would argue as the general contractor. Only the general contractor knows what costs and savings were applied in the surcharge. If you want to widen outward, then it simply costs even more.
By the way, the living room would need to have 38m (125 feet) of exterior wall for 6.5cm (2.6 inches) to add up to 2.5m² (27 ft²).
In my opinion, structural dimensions and living space calculations are being confused here and everything is being attributed solely to the widening of the walls.
ypg schrieb:
Define preliminary design.
So, you probably have the fine print. And it depends on the contract. In the end, you are building with a general contractor (GC). The question is how the price is actually determined with the GC. Often, the GC relies on a catalog house or on a drawing that is included in the contract along with the scope of work description.
It is very rare, when building with a GC, to have pricing based on living area.
Often, you have the standard model house Florentine with about 150sqm (1600 sq ft) of living space on a slab foundation and the corresponding scope of work description. Everything that is customized is based on special requests, also adjusted for energy efficiency. The scope of work refers to the Renewable Energy Act (or formerly KfW), which the catalog price is based on.
Then adjustments are made, sometimes by a few centimeters, sometimes to the height. For example, the roof pitch often has to be changed if the development plan requires it or if the client wants a different staircase.
And that should be clearly stated in the contract.
However, I don’t know any GC who locks themselves to fixed numbers in advance. They allow some freedom so that adjustments do not need to be recalculated.
If you are not happy with this regarding the building permit, then you need to discuss it. You don’t have to sign it, but you should clarify to what extent the living area is capped in the contract.
This rarely happens with a general contractor. It is not an architect-designed home with a tender, but a turnkey house according to the scope of work for you as the builder. Let’s say it this way: the mixed calculation is none of your concern as the client. It simply follows standard model houses and their standard and surcharge changes.
Is the expansion not worth it because of a few centimeters? That is unreasonable.Thank you for the post.
By preliminary design, I mean the draft typically created with a GC before signing anything. For example, it didn’t contain exact room dimensions, only what is shown here. I have simply uploaded the draft and the drawing for the building permit. Maybe it will become clearer what I mean. I should also mention that this is not a catalog floor plan in this case, as we pre-drew everything ourselves (only with desired room sizes, without exact measurements) and sent it to the GC, who then professionally drew up the design.
ITSM2025 schrieb:
You can’t just assume a narrower masonry in advance. Yes, you can. The masonry is likely specified in the scope of work.
In addition, you have the upgrade to a higher KfW 40 standard, which can also affect the exterior walls.
However, from what I recall: when we upgraded to the then KfW 70, the exterior insulation increased from 12 to 14 or 16 cm (5 to 6 or 6.3 inches), but only on the outside. The interior remained the same.
Again: check the scope of work and the contract, which we don’t have.
Also: it’s a mistake as a homeowner to calculate costs per square meter (square foot) at this stage. There are other costs you need to consider as well.
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