The living space is approximately 8 m² smaller in the application drawings compared to the draft (GU).

2025-04-16 13:40:47

unfortunately I was smarter than everyone else here in the forum

Proof No. 1: You don’t show the draft, so we are supposed to talk about the color like the blind;
Proof No. 2: You "calculate" with more wall thickness resulting in less (!) material for the walls.

or whether that is simply standard in the construction industry.

Yes, of course a GU’s signature pawn takes away the space for a wall thickening on the inside. Where else would it come from.

How do you assess the whole thing and how would you act in this situation?

In your place as a "smarter than the others" client, of course with an email: "please calculate for a changed offer the wall thickening to the outside instead of to the inside."
A truly smart client would now also still discuss and question the entire draft here – naturally also in "detail", whether the EH-Fettstufe 40 really is the bomb.
And my advisers would never commit to a construction method including a specific GU. By the way, they also go to architects who know and apply a preliminary draft as a design maturity stage, and do not misuse it as a term for a "not yet final" draft.

have been a silent reader for a long time now

But at least not an attentive one. Otherwise, you would know that by choosing calcium silicate brick, you of course can’t manage with caliber 425 in EH40. Sometimes you literally write against walls.

2025-04-16 13:48:41

Why does the roof absolutely have to become bigger? With a hipped roof, the overhang can simply shrink.

The overhang is usually defined in the construction performance description. If it simply becomes smaller, there will rightfully be complaints. So the roof would necessarily have to become bigger.

And if 14cm more external dimension becomes a problem, the plot is too small for the planned house anyway

But if you build 6m away from the boundary because you plan a double garage and then the outer wall becomes 6cm thicker afterwards, only 5.94m remains and the garage doesn't fit. Then it doesn't matter how large the plot on the other side is.

Also, we pay an extra surcharge for the upgrade to KfW 40.

Which would of course have become more expensive if the extension went outward. At least that's how I would argue as a general contractor. Only the general contractor sees what additional costs and savings were settled in the surcharge. If you want a widening outward, it simply costs even more.

By the way, the living room would have to have 38m of exterior wall for the 6.5cm to add up to 2.5m². In my opinion, raw construction dimensions and living space calculation are confused here and everything is completely attributed to the widening of the walls.

2025-04-16 13:58:15

Define preliminary draft. So, you certainly have fine print. And it depends on the contract. Ultimately, you are building with a general contractor (GC). The question is how the price is determined with the GC in the first place. Often, the GC relies on a catalog house or on a drawing that is taken as part of the contract including the scope of services description. It is very rare, when building with a GC, that pricing is based on living area. Often there is the model house Florentine with about 150 sqm living area (approximately!) on a slab foundation and the corresponding scope of services description. Everything that is adjusted is based on special requests, also adjusted energetically. The scope of services description refers to the Renewable Energy Act (or previously KfW), on which the catalog price is based. Then an adjustment is made, sometimes to the disadvantage of a few centimeters, sometimes it is the height. For example, the roof pitch often has to be adjusted if the development plan prescribes something or if, for example, the builder wants a different staircase. And that should also be stated in the contract. However, I wouldn’t know that a GC commits to fixed numbers in advance. He allows himself freedoms so that adjustments do not have to be recalculated. If you are not satisfied with this regarding the building permit, then you need to talk. You don’t have to sign it, but you should clarify to what extent the living area is capped in the contract. Such things rarely happen with a general contractor. It is not an architect’s house with tendering, but the turnkey house for you as the builder according to the scope of services description. Let’s put it this way: the mixed calculation does not concern you as the builder. It’s simply about model houses, their standard, and surcharge changes. Is it not worth doing an extension for a few centimeters? That is unreasonable.

Thank you for the post. By preliminary draft I mean the draft you typically create with a GC before signing anything. For example, it did not have exact room measurements but only as shown attached. I have simply uploaded the draft and the drawing for the building permit here for you. Perhaps this will make clearer what I mean. I must also say that in this case it is not a catalog floor plan since we drew everything ourselves beforehand (only with desired room areas, without exact dimensions) and sent it to the GC, who then drew the draft more professionally.

2025-04-16 14:12:14

You can’t just assume thinner masonry in advance.

Yes, you can. The masonry is presumably specified in the construction service description. In addition, you have the upgrade to a higher KFW 40, which can also affect the exterior walls. However, I have to say: from what I remember, we upgraded to a KFW70 back then, and the external insulation was increased from 12 to 14 or 16 cm, but on the outside. Inside everything remained the same. Again: check the construction service description and the contract, which we do not know. And: it is a mistake for the builder to calculate costs per sqm now. Other costs will come up that need to be included.

2025-04-16 14:13:29

Your drawing is too small and therefore blurry.

2025-04-16 14:33:21

Are they possibly working now? Unfortunately, I couldn't crop the more detailed drawing any better.

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The living space is approximately 8 m² smaller in the application drawings compared to the draft (GU).

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