160m2 detached house in timber frame construction on the north slope with basement

Perhaps one could also swap the living room with the kitchen (also move the walls), making it more inviting and open when you walk up the stairs and find yourself directly in the living/dining area. What else I notice: in my opinion, the bathtub in the master bathroom is too close to the door. You can open the door, yes, but it is not barrier-free.

First of all, thank you very much for the numerous, mostly constructive responses.

Did the seller draw this himself, or did they actually hire an architect? To me, it looks more like a seller’s draft that wasn’t very detailed.

Correct, this is a seller’s draft (but he is a civil engineer). However, I’m not sure to what extent the company’s architects can still improve it.

What does the ventilation concept look like?

There isn’t one, meaning manual ventilation. Several companies told us that to prevent mold, no controlled residential ventilation or similar is necessary for these houses.

Is there already a structural analysis included in the price?

There isn’t one, but it is included in the price.

What about the earthworks?

They are added on top.

Do you really not want a water-impermeable wall on the slope?

Yes, according to the soil survey it is necessary; according to the mentioned civil engineer, probably not. I think I will insist on it anyway. That would add to the cost.

What about the outdoor areas? That is especially expensive with slopes. Be careful with timing and DIY work. Often a digger is needed. Fill here, excavate there, and possibly dispose. Not every excavation material can or should be reused for filling. For a wall there, an L-stone.

We don’t know exactly how we will handle that yet. We will probably have the necessary work done directly.

What is included in the offer?
How complete is the electrical installation, what brands for sanitary fixtures?

This is a high-quality “turnkey” package. The lower-end lines of good brands are included for sanitary fixtures. Everything needed for the electrical installation is included. We might have to add a few sockets here and there, but nothing major.

Your budget is tight

We know that, which is why we chose a prefab house company. The risk of nasty surprises is not as high as with an architect. Especially with a 110% financing...

We know that, which is why a prefabricated house company. That is where the risk of nasty surprises lies

I cannot agree with that. On the one hand, it depends very much on the content of your construction services description, but also on many costs outside the house. The prefabricated house provider delivers from the top edge of the base plate (or in your case with a finished basement). But regarding costs not included for the construction as well as especially development, outdoor facilities, etc., significant additional charges can very well occur. A few examples have already been mentioned above, but also with the house, some construction service descriptions lack crucial items that later result in five-figure amounts. Do not be misled by the term "turnkey," as it can be very far from what you colloquially imagine.

I cannot agree with that. On the one hand, it depends very much on the content of your construction service description, but also on many costs outside the house. The prefabricated house provider delivers from the top edge of the floor slab (or in your case with a finished basement). But with regard to costs not included in the price for construction as well as especially development, outdoor facilities, etc., significant additional charges can very well arise. A few examples have already been mentioned above, but even with the house there are sometimes serious items missing in some construction service descriptions that can result in five-figure amounts afterwards. Don’t be misled by the term "turnkey," it can be very far from what you colloquially imagine.

I almost know the construction service description by heart now and we have already done a factory tour including preliminary sampling and therefore know quite exactly what is included in the standard. The nasty surprises with groundworks etc. that you mention can just as well happen with the architect + possible nasty surprises with every trade etc. To protect ourselves, we would simply have to include a lot more buffer.

I will soon know the construction service description by heart and we have already done a factory tour including preliminary sampling and therefore know quite exactly what is standard.

I don't want to talk down the construction project to you, but the well-meant advice is: The decisive factor is not what is included, but what is NOT included and that you therefore do not miss at first, but should be included. You will also not be able to see this during the factory visit or preliminary sampling.

This is not meant to spoil your fun building, but from experience, the price is not equal to land + house price + exterior facilities and development... as one might initially believe. You are actually well advised to have a "buffer". In my environment, none of the builders in the last two years have come even close to the originally estimated completion price. And this was neither due to water taps gilded afterwards, nor a swimming pool hidden under the living room floor with hydraulically sliding plates or the underground garage under the house with a car elevator. Rather, it was many, many positions that were added outside the original calculation, even with prefab houses or general contractors.

There is none, meaning ventilation is done manually. Several companies told us that to prevent mold in these houses, no controlled residential ventilation or the like is necessary.

Then I would ask about the ventilation concept. Although it is not directly required by the Energy Saving Ordinance, it is actually necessary or often already standard. It should not be a problem for a prefab house builder. For a new super-tight Energy Saving Ordinance building, you definitely have to do something. From controlled residential ventilation, decentralized systems, to window frame ventilators? With our old building with fairly tight retrofitted windows, I am also currently exploring the possibilities, because it simply does not work without.

Regarding electricity: Do you know how much an additional socket costs you? Is network cabling included? Sat? For everything that has to be additionally installed in the walls by prefab house manufacturers, you often have to be really careful!

In general, a prefab house is more expensive than a normal construction.