Tile installation with additional costs for large format

Just the material costs of 2707 euros. You can get nice wood-look tiles in this format for 30-40 euros per sqm.

It doesn't help if the OP chose more expensive ones and the construction service description only budgets 20€/sqm.

But what is supposed to be the third item then?

You pay for the term, for a deviation, you pay more for mainstream and for what stirs desire.
You pay for everything that deviates – whether justified or not.
If I pay 20€ for an updo at the hairdresser, I pay 65€ for the same service for my own wedding... call it an upcharge name, you pay more.

The additional costs for the tiles can have an even more banal background. A tile that cost 25 EUR/m² two years ago now easily costs 35-40 EUR/m². So if you don't want significantly cheaper tiles, considerable additional costs arise. And most people also sample the tiles because the 25 EUR/m² from 2021 already seems too cheap to them...

And yes, large-format tiles cause considerable extra effort because they
- must be laid on an uncoupling mat. It has to be cut, fully glued, taped at the transitions with fabric tape, and then fully filled again
- can hardly be handled properly by one person anymore, so two people are needed

We also build with a developer.

You do not build with a developer; you can only buy from them. According to the billing statement

I have been in a construction phase for two years. Now finally tiling is being done. The developer charged me an additional cost supplement for large format tiles of €7,977.00. It concerns the floor tiling of 94 sqm. The tile size is 120x20. The additional cost effort is listed in the invoice as follows:

it seems to me, however, that the OP has a general contractor. This apparent hair-splitting is important because some companies operate both as developers and as general contractors, but you can only have a contractual relationship with one or the other—and that makes a significant difference.

More waste More effort Difficult handling, longer execution

Not to forget: first and foremost, the required flatness of the substrate is in a completely different league.

@ First of all, I do not believe that ceramic tiles in the format 120cm x 20cm have been or are intended to be installed. The risk of breakage during transport and/or installation itself would be an almost incalculable risk. So let us assume a format of 1.2m x 1.2m, a large format. In contrast to "normal installation," four aspects must be particularly considered with large formats, which significantly affect costs: 1.) the substrate must have an increased flatness (according to DIN 18202 Table 3 Row 4) 2.) the tile adhesive must be applied using the buttering-floating method (higher material consumption) 3.) large formats, which together with the applied adhesive (see above) bring a not insignificant own weight, cannot be installed as easily as smaller formats. Sometimes an appropriate lifting technique is necessary, as the installer has only one attempt! Once the large-format tile is placed in possibly an unfavorable position, it is almost impossible to correct this position. For those who do not understand this: if a glass pane is placed on another pane, they can only be separated again with great difficulty. The adhesive bond (unlike the cohesive bond of glass panes) also exists between tile and tile adhesive. 4.) waste. This topic was already mentioned by another forum participant, and he is right. --------------------------- There are thus a number of special features in the installation of large-format tiles and slabs that must all be paid for. Whether the amount mentioned in the initial post is justified can probably be judged by no one objectively. THAT however there will be additional costs with such an installation/installation technique must is undisputed. I hope these notes were helpful. Greetings to all: KlaRa

It concerns the floor tiling of 94sqm.
1. Additional material tiles extra cost €2707.00
2. Additional extra cost laying €1770.00
3. Additional extra cost large format €3500.00.

1. You should be able to request proof here. You usually have a fixed price per sqm in your construction service description and then have to pay the additional costs. For you, it's roughly €28 more per sqm. So you chose a tile that costs €28 more per sqm than specified. That seems quite a lot to me; there are certainly cheaper models that look just as good?
2. I find €19/sqm additional cost for laying justified. With such large tiles, you have to take a lot into account and may even need two people. That obviously makes it more expensive directly. For us, for example, everything up to 60x60 in laying was cost-neutral.
3. This point doesn’t seem quite consistent to me since the additional tile costs and additional laying costs have already been calculated. Maybe ask what is behind this position? Shipping costs? Replastering again in Q3, Q4, due to higher flatness requirements?

So points 1 and 2 seem reasonable to me. Point 1 results from your sampling and point 2 is the effort for the tiler. I would ask again about point 3.

And as already mentioned: item 3 can also arise from the construction service description. Namely, if tiles were not planned for the 94 sqm, but another floor. Then the possibly higher installation effort for tiles can be calculated accordingly. This is the case with us, however, we pay significantly less proportionally because there is a compensation.