How expensive was your conscription / hidden costs?

For me, upgrades and hidden costs are two different things.

Upgrades are "nice to haves" that you can choose to upgrade if you want, and hidden costs are items without which I cannot properly finish the house. The line is certainly blurry, but it makes a big difference whether it is, for example, an upgrade to more expensive tiles (the cheaper ones would do in a pinch), or whether the construction specification does not include a (suitable) waterproofing for your basement, without which your house is not protected against pressure water in an emergency.

To be able to help you, it would be good if you let the cat out of the bag – which [Fertighaus-Anbieter] is it? Maybe someone in the forum here has concrete experience with them.

.. and always look very carefully at everything that has to be provided by the builder, that is by you. Foundation slab, possibly more excavation, utility connections, outdoor facilities have already been mentioned (rudimentary work such as splash protection, house access are definitely necessary) and all other possible construction costs that come in addition to the "turnkey" house.

The classic hidden cost in prefabricated houses from [OK Bodenplatte] onwards is the floor slab itself.

What did you downgrade? Instead, own work, or just things like removing the tub, one less washbasin, smaller shower, ...?

A huge chunk was the shower fittings being surface-mounted instead of concealed. Off the top of my head, that alone accounted for 1.5-2k per shower. Also, with the fittings themselves, we kept our eyes open a bit and paid less for the 4+1 sets of fittings at the sanitary dealer than standard – although without exception all toilets are rimless and one bathroom even has a luxury series that has just been discontinued. To give each bathroom a theme, I had different and really stylish glass mosaic tiles installed in each bathroom, so we definitely treated ourselves there, and when someone enters the bathrooms, the first impression is WOW. One bathroom also has a urinal (absolutely recommended) and one bathroom has a huge tub. All showers are large and level with the floor; one bathroom has a built-up and tiled shower wall with a niche.

Doing plumbing myself is too risky for me and I’m not good enough at tiling. I didn’t do anything myself in the bathrooms except network cables, speaker cables, and power cables in the toilets in case a luxury toilet is ever installed.

Two more things:

A real shock was the electricity bill for the screed drying heating. Wow, that was a really big amount. Should be clarified beforehand - but you can't change it anyway.

What I always find difficult with all the quantity surveys is the susceptibility to errors. Our quantity survey got lost which contained three important points: 1. Additional empty conduits 2. Heat pump on the garage 3. Plastered exterior walls in the basement. I laid the empty conduits myself and then, since it was forgotten, got some money refunded so it didn't have to be redone. The heat pump on the garage was more difficult because the electrician didn’t lay any power line to the garage, and everything inside the house was plastered over again and I panicked and alarmed the electrician and the construction manager to please lay it before it was plastered over. It was quite chaotic but just managed to work out. The plastered exterior walls were really annoying because the construction manager resisted it strongly – of course, he had also bungled the entire additional claim. Then, after the tiles were laid, plastering was done, but that is of course only a thin coat plaster. As a result, the basement rooms unfortunately have a noticeable basement-feeling in the acoustics.

What I mean is: Every additional claim is a change and every change is annoying.

The classic hidden cost in prefab houses from OK floor slab onwards is the floor slab itself.

I am currently dealing with having everything up to the "Oberkannte Bodenplatte" commissioned myself. It is really not to be underestimated.